Temagami greenstone belt
Encyclopedia
The Temagami greenstone belt, also known as the Temagami volcanic belt and the Temagami metavolcanic belt, is a small 2.7 billion year old greenstone belt
in the Temagami region of Northeastern Ontario
, Canada. It represents a feature of the Superior craton
, an ancient and stable part of the Earth's lithosphere
that forms the core of the North America
n continent
and Canadian Shield
. The belt is composed of metamorphosed
volcanic rock
s that range in composition from basalt
to rhyolite
. These form the east-northeast trend of the belt and are overlain by metamorphosed sedimentary rock
s. They were created during several volcanic episodes involving a variety of eruptive styles ranging from passive lava eruptions
to viscous explosive eruption
s.
Part of the Canadian Shield, the Temagami greenstone belt contains some of the oldest known rocks on Earth. The belt is made up of a number of geologic features such as batholith
s, stocks, dikes
, volcanic complexes, layered intrusions and deformation zones. These are situated in several geographical townships
in the municipality of Temagami, including Chambers, Strathy
, Strathcona, Briggs and possibly Best.
tism, metamorphism and sedimentation
. They are important economically for large metal deposits, and for the insight they provide into crustal
evolution and the tectonics
of the early Earth. The Temagami greenstone belt is wide and long. It contains the southernmost remnants of Archean
intrusive and supracrustal rock
s in Eastern Ontario
, as well as some of the most ancient felsic
magmatic events in this section of the Superior craton. Uranium-lead dating
has established that the Iceland Lake Pluton
, as well as an adjacent rhyolitic lava flow, is about 2,736 million years old. Therefore at least some intrusion
s were likely formed during the first volcanic phases in the belt and may have been conduits for volcanic eruptions.
The variety of volcanic deposits and intrusions in the Temagami greenstone belt indicates that magmatic activity played a significant part in its formation. Pillow lava
is found throughout the belt, indicating lava erupted underwater. Its pyroclastic deposits
are remnants of explosive volcanism
. The oldest exposed rocks within the belt are fine to medium-grained basalts and andesite
s. Lava flow units range in thickness from to . Mafic agglomerate
and breccia
are relatively abundant, being either massive and undeformed, or sheared. Dacitic lava flows or tuff
s overlie these metamorphosed volcanic rocks along with intermediate
volcanic breccias, and are overlain by rhyolite lava flows and tuffs. Acidic lava flow units range in thickness from to and are common in the Vermilion Lake and Link Lake areas. The felsic tuffs are normally altered and sheared. The most recent intrusive activity in the Temagami greenstone belt was the formation of a rhyolite porphyry dike million years ago. This age correlates well with the 2675–2700 million year old intrusions throughout the Abitibi Subprovince, but the 2736 million year old magmatic events in the Temagami greenstone belt are older than the closest exposed portion of the Abitibi Subprovince, about north of Kirkland Lake.
Along with nearby granitic intrusions, the Temagami greenstone belt is bounded by layers of rock comprising the Huronian Supergroup
. Strathy Township is dominated by metamorphosed volcanic rocks of the northeastern portion of the belt. It is approximately north of the Grenville Front Tectonic Zone
. The volcanic rocks possibly total as much as thick. However, portions of the sequence might have been repeatedly sheared by one or several local fault zones. Every large volcanic event is capped by metamorphosed sedimentary rocks and/or iron formations
. The metamorphosed sedimentary units range in thickness from to and consist of laminated slate
and greywacke
with or without volcanogenic tuffs. The iron formations are composed of alternate layers of magnetite
, white quartzite
, jasper
, grey chert
y quartz, and/or tremolite
-chlorite
tuff. They are intruded by sills
composed of medium-grained, white-weathering, quartz diorite
that range in thickness from to . These rocks are similar to the coarse thicker parts of lava flows, but are interpreted to be partly intrusive, likely conduits that produced mafic volcanism.
, gabbro
and anorthositic gabbro has been found in northwestern Strathy Township. Pyrrhotite
is common in associated pyroclastic rock
. Several northeast-trending shear zone
s less than wide intersect the edifice, extending along the Net Lake-Vermilion Lake Deformation Zone
. This layered intrusion might be similar in age to the Kanichee layered intrusive complex
, and may represent a magma chamber
that was the source of tholeiitic volcanic activity.
The Kanichee layered intrusive complex, also known as the Kanichee Intrusion and Ajax Intrusion, is the most voluminous mafic-ultramafic body in metamorphosed felsic and mafic volcanic rocks of the northern Temagami greenstone belt. It is an oval-shaped layered intrusion that was formed during five phases of magmatic activity. A series of south-southeast dipping cyclic magmatic layers make up the intrusion, similar to those of the surrounding metamorphosed volcanic rocks, indicating that the rocks of the intrusion were formed horizontally and likely close to the surface. Numerous magmatic events may have breached the surface to produce volcanic eruptions. The overall structure of the intrusion indicates it is cylindrical in shape and has a long axis plunging to the southeast at a somewhat steep angle. Its fairly steep angled axis was formed by at least one period of deformation that similarly folded and deformed the surrounding volcanic rocks.
An intrusion of light-coloured diorite lies at the northern end of the Tetapaga Syncline
, along the Milne-Sherman Road. Its colouration is from weathering of plagioclase
, which comprises more than 50% of the intrusive rock. Several east-trending high-strain zones related to the Link Lake Deformation Zone
, less than wide, are found in the intrusion, indicating that it formed at least before the last increment of strain along the Link Lake Deformation Zone. The dioritic intrusion might be the remains of a magma chamber that was the product of calc-alkaline
feldspar
-phyric felsic volcanism, the erupted products of which are mostly located in the Sherman Mine
area.
At least three large granitoid
intrusion
s penetrate the Temagami greenstone belt. The Spawning Lake Stock
in Briggs and Chambers township
s contains megacryst
s that reach to in diameter. It shears through the nearby fold axis of the Tetapaga Syncline, but remains undeformed by the western expression of the Net Lake-Vermilion Lake Deformation Zone. To the north and northeast, the massive Chambers-Strathy Batholith was formed during one magmatic event. It consists of intrusive rocks ranging from pink to grey quartz monzonite
to granodiorite
and intrudes metamorphosed volcanic rocks of the Temagami greenstone belt. The Iceland Lake Pluton, situated in Strathcona and Briggs townships, consists of a complex series of chlorite trondhjemite
, hornblende
quartz diorite and hornblende trondhjemite magmas that were emplaced during more than one magmatic event. The trend of metamorphosed volcanic rocks in Briggs and Strathcona townships is parallel to the intrusion contact. A planar fabric
, attributed to the earliest deformation of the Temagami greenstone belt, exists in the outer margin of the intrusion.
Intrusive dikes composed of quartz and feldspar-quartz porphyry are widespread in Strathy Township. All dike types were placed in the Earth's crust during the formation of the Temagami greenstone belt. At least some of these dikes may have been subvolcanic
feeders that produced known calc-alkalic felsic volcanic events in the belt. Many pyroxenite dikes less than 2 m (6.6 ft) wide intrude every geologic formation in the township. A pyroxenite dike east of Highway 11 extends roughly to the north-northwest while two others, north of Arsenic Lake
, extend to the east. This includes a dike exposed along the Kanichee Mine Road in Temagami North, where it intrudes the large granitic Chambers-Strathy Batholith. A series of northwest-trending dikes composed of diabase
may represent extensions of the 1,250 million year old Sudbury dike swarm
. This dike swarm
is older than the Lake Wanapitei
impact crater
but younger than the meteorite impact that created the large Sudbury Basin
crater about 1,850 million years ago. Therefore, the Temagami greenstone belt predates these two impact craters, the Sudbury crater of which is the seconed largest known impact crater on Earth.
. Remnants of a large volcanic vent are present west of Sherman Mine, including the existence of two felsic lava flows that outcrop between Link Lake and Turtle Lake
. The aspect of the most extensive felsic lava flow indicates that the volcanic vent they erupted from was adjacent to the western portion of Link Lake. Additionally, differentiation of facies and directions in which the lava traveled exist in course grained, resedimented conglomerate
. This suggests that a more prominent structure, perhaps evidence of a prehistoric volcano
, existed west of Link Lake. Also, coarsest felsic volcanic fragments occur in feldspar-phyric pyroclastic deposits exposed on the Sherman Mine property, suggesting the approximate location of a volcanic vent.
Just north of the Milne Townsite lies a minor felsic volcanic vent exposed along the Milne-Sherman Road. A quartz porphyry has intruded mafic and rhyolitic lava flows and a dike of diorite. In the middle of the intrusive body, the grain size of quartz phenocryst
s averages roughly , but become smaller towards the edge of the intrusion. Broken fragmental rocks, interpreted to be carapace breccia, are exposed along the western margin of the intrusion. Exposed near a minor felsic lava dome
is a fine grained, quartz-phyric felsic rock that may represent a rhyolite lava flow. An igneous body, interpreted to be a subvolcanic intrusion, is exposed approximately to the northwest and might have formed during the same magmatic event as the felsic dome. Exposed along the Sherman Mine railroad west of the former Milne sawmill lumber yard is a porphyritic body composed of quartz-feldspar. It is unknown if this igneous rock is a rhyolitic lava flow or an intrusion.
Several north-trending felsic dikes, composed mainly of feldspar and quartz-feldspar, are located north of the former Temagami garbage dump. These dikes are not known to extend across the Link Lake Deformation Zone, suggesting that they might represent the feeders of a minor volcanic vent, manifest now by felsic lava flows. Because certain lithologies can be correlated through the Link Lake Deformation Zone, it is unlikely that the lack of felsic dikes south of the former town dump area is an expression of displacement along the deformation zone.
The Temagami greenstone belt consists of two large volcanic sequences that were formed during several phases of volcanic activity. These two sequences, known as the Older and Younger volcanic complexes, consist of volcanic rocks ranging in composition from felsic to mafic. The Older Volcanic Complex is composed mainly of felsic lava flows and pyroclastic deposits with smaller amounts of mafic volcanic rocks. It underlies a large portion of northwestern Strathy Township and is penetrated by mafic intrusions, although the Kanichee Intrusion consists of peridotite
and pyroxenite, which are ultramafic rocks. Just to the southeast, the Younger Volcanic Complex consists mainly of mafic volcanic rocks that form four geologic formation
s. The Arsenic Lake Formation is composed of dark green, iron-rich, massive and pillowed tholeiitic basalts. Throughout the Arsenic Lake Formation are feldspar-phyric basaltic lava flows. This type of basalt contains tabular feldspar phenocrysts that range up to in cross section. Both pillowed and massive lava flows have been known to contain coarse feldspar. Coarse feldspar-bearing, iron tholeiitic basalts are more common east of Highway 11.
A number of volcanic rocks comprise the Link Lake Formation, such as feldspar-phyric, calc-alkaline basalt and andesite lava flows and less abundant quartz and quartz-feldspar-phyric felsic lava flows. Feldspar-phyric basalt lava flows are normally pillowed. Pyroclastic deposits, quartz-phyric and feldspar-felsic rocks are also present. The largest of the less common felsic lava flows is located between Link Lake and Turtle Lake. It is 2.5 km (1.6 mi) long and less than 200 m (656.2 ft) thick. The thickest portion of this lava flow or dome is located at the western end of Link Lake, where it is likely associated with a volcanic vent. The bulk of felsic rock in the Link Lake Formation occurs as subaqueous pyroclastic flow
deposits. Subearial pyroclastics are normally quartz-phyric and range up to in crosssection. Dark green subearial pyroclastics composed of chlorite and sericite
are uncommon and have sustained preferential compression in response to shear throughout the Link Lake Deformation Zone. These dark compressed pyroclastics have been interpreted to be pumice
. Some of the subsequence pyroclastic deposits contain fragments of pyrite
and quartz, suggesting that discharged sulfide hydrothermal activity
took place throughout the volcanic source area.
Resedimented felsic, epiclastic and turbiditic sediments compose the Turtle Lake Formation. The base of this formation consists of a heterolithic, volcaniclastic, matrix
-supported conglomerate unit that overlies felsic lava flows and pillowed, calc-alkaline basalts of the Link Lake Formation. Many rounded to subangular felsic and mafic volcanic fragments are known to occur in the unit, as well as rare quartz vein fragments and one fragment of white chert. The conglomerate unit passes laterally and vertically into thin bedded deposits. These thin bedded deposits are interpreted to be turbidite
s that originated from a felsic volcanic vent at the western end of Link Lake. Many dark green, highly vesicular, iron-rich tholeiitic basalts occur in the Turtle Lake Formation, and are interbedded with thin-bedded wackes on the southern limb of the Tetapaga Syncline. The basalts are best exposed along the south shore of Turtle Lake. In some cases, the basalt vesicles are over in diameter and are now filled by white quartz.
A series of dark green, massive and pillowed iron-rich tholeiitic basalt lava flows compose an unnamed upper volcanic formation of the Younger Volcanic Complex. It is situated in the core of the Tetapaga Syncline. Not much is known about this volcanic formation because only a small portion of it remains exposed in western Strathy Township.
situated near the former garbage dump of Temagami. The felsic dikes near this zone are interpreted to represent a subvolcanic feeder system to the overlying felsic volcanic rocks. It is probable that the dikes maintained a former zone of weakness now demonstrated by the shear zones. Renewed tectonic activity along the Big Dan Shear Zone is manifested by offset of clastic sediments east of the Ontario Northland Railway
. This phase of tectonic activity displaced felsic dikes north of the exposed part of this shear zone. However, considerable displacement of the dikes at this location is unknown. The most recent phase of tectonic activity along the Big Dan Shear Zone resulted in the displacement of a Proterozoic
dike composed of diabase, which intersects the zone. A similar abundance of felsic dikes are adjacent to Arsenic Lake just west of Highway 11, indicating similar repetitive tectonism also occurred along that structural zone. Therefore the north-trending shear zones may have been active for at least a billion years.
Extending from Net Lake
to Vermilion Lake lies a northeast-southwest trending high strain zone known as the Net Lake-Vermilion Lake Deformation Zone. Because geologic mapping has not been done comprehensively throughout this zone, its exact width is unknown. The expression of this deformation zone is clearly identifiable by the intense change in volcanic rocks of the Temagami greenstone belt. Volcanic units comprising the northwestern portion of the shear zone have shifted to the northeast while the volcanic rocks comprising its southeastern portion have shifted to the southwest. Along the northeastern arm of Lake Temagami
in Strathcona Township lies the Northeast Arm Deformation Zone
. This northeast-trending shear zone has not been studied in detail, but casual studies of many islands along the northeastern arm of Lake Temagami have shown that there is severe foliation
and minor ferroan carbonate
across an area about wide. The Link Lake Deformation Zone, also known as the Link Lake Shear Zone, is an area of deformation wide and over long in Strathy Township. It extends through Link Lake to east of Highway 11, but it is uncertain whether it extends west of Link Lake because no expression of it has been found in the Sherman Mine area. Therefore the Link Lake Shear Zone might be a northern extension of the Northeast Arm Deformation Zone further south. Strain intensity of the Link Lake Shear Zone is diverse. Generally, the greatest strain intensity is throughout pyroclastic rocks. Extending from the western boundary of central Chambers Township through Tasse Lake to the east is the Tasse Lake Deformation Zone
. This deformation zone is roughly long and at least wide. It is uncertain if this deformation zone extends east of Tasse Lake.
grade metamorphism, even though amphibolite
grade metamorphism surrounds the Chambers-Strathy Batholith. The metamorphism that creates greenschist is minimal in contrast to that which creates rocks such as gneiss
. Other rock alterations include small veins of quartz and epidote
, vesicles filled with quartz, calcite
and chlorite, extensive replacement of volcanic rock by silica or calcite, and calcite precipitation in extension fractures.
Outcrops of silicified mafic pillow lava are found along and west of the Ontario Northland Railway, east of the Big Dan Shear Zone and adjacent to Outlet Bay and Boot Bay of Net Lake. This form of alteration occurs in deformation zones and is the product of low temperature seawater
alteration. Volcanic rock replaced by carbonate is commonly found in the Northeast Arm Deformation Zone, the Link Lake Shear Zone and in the Net Lake-Vermilion Lake Deformation Zone. Within the high strain zones, carbonate is also manifest as 1 m (3.3 ft) wide veins that have been traced along strike for more than .
Basalt has been replaced by calcite in a restricted area just north of the Temagami's former garbage dump. Although developed adjacent to the Link Lake Shear Zone, rocks within and just outside the calcite alteration zone do not normally contain significant foliation. Thus, if the calcite alteration zone was located within the Link Lake Shear Zone, it did not form inside the zone of the highest strain.
s and several precious metal
and base metal
deposits. The banded iron formations range from to to more than thick. Remnants of volcanic vents are an important locator for mineral
potential in the Temagami belt because they are adjacent to rocks that contain certain types of mineralization
. At the Link Lake Formation, good evidence for copper
-zinc
massive sulfide deposits has been discovered in associated volcanic rocks. Some gold
mineralization may also be associated with volcanic vents. Studies of greenstone terrane
s in the Superior craton have shown that large gold deposits are associated with regional deformation zones. Therefore, the Northeast Arm Deformation Zone, the Link Lake Shear Zone and the Net Lake-Vermilion Lake Deformation Zone are obvious high potential areas. A number of scattered pyrite deposits can be found throughout the Northeast Arm Deformation Zone. The high frequency of gold mineralization in and near the Net Lake-Vermilion Lake Deformation Zone suggests that this deformation zone may very well also contain gold deposits; at least 11 have been discovered within a 4 km (2.5 mi) length of the deformation zone. The gold deposits are found in many rock types, indicating a stronger gold-bearing system with the potential of larger gold deposits. A number of gold-pyrite deposits exist in felsic volcanic rocks overlying the Older Volcanic Complex, near and on the northwestern part of the Net Lake-Vermilion Lake Deformation Zone. These deposits were likely formed during the creation of the Net Lake-Vermilion Lake Deformation Zone. At the Younger Volcanic Complex, gold exists in quartz veins containing base metal sulfides. It is also known to exist in pyrite associated with deformed magnetite-rich iron formations, sericitized and carbonatized felsic volcanic rock, quartz-pyrrhotite
-chalcopyrite
-pentlandite
-pyrite zones within deformation zones and in north-trending, chloritized shear zones containing arsenopyrite
, pyrrhotite, pyrite and chalcopyrite.
A variety of iron, copper, arsenic
and zinc ore
s such as arsenopyrite, pyrrhotite, pyrite and chalcopyrite with sphalerite, are present as small veins and in quartz veins throughout north-trending shear zones that cut the iron-rich tholeiitic basalts of the Arsenic Lake Formation. Dikes composed of quartz-feldspar porphyry run parallel to or lie within the shear zones and are cut by the mineralization. Chalcopyrite occupies later fractures which intersect massive arsenopyrite. Sparse quartz veins normally exist in or adjacent to the arsenopyrite-rich zones. Several northeast-trending deformation zones intersect pyroxenite of a mafic sill in northwest Strathy Township. Within these high-strain zones quartz veins normally contain chalcopyrite, pyrite, pyrrhotite with exsolved pentlandite and traces of sphalerite and galena. Chalcopyrite, pyrrhotite and pentlandite are deposited throughout shear zones which lack quartz veining. These zones are not known to contain large amounts of gold, although investigations are incomplete. It is also unknown if platinum group
metals (which include platinum
, palladium
, rhodium
, iridium
, osmium
and ruthenium
) exist in these zones because no searches for platinum group elements have been undertaken.
Gold and copper values occupy a northeast-trending iron formation within the Net Lake-Vermilion Lake Deformation Zone. This mineralization is only known to exist southeast of Cooke Lake and immediately south of Net Lake. A unit of chert, magnetite and pyrrhotite outcrops along the southwest shore of Net Lake at Temagami North. Pyrrhotite, the most common sulfide mineral, occurs as small veins and disseminations. Small amounts of pyrite, sphalerite and exsolved pentlandite and chalcopyrite are present with the pyrrhotite. The main exposure lies immediately south of the Kanichee Mine Road, which branches off Highway 11. Minor gold and copper values constitute this zone. This sulfide-bearing unit is located within felsic volcanic rocks of the Older Volcanic Complex and is capped by large, dark green, iron-rich tholeiitic basalts of the Arsenic Lake Formation. It has been interpreted that the sulfide zone represents a volcanogenic massive sulfide ore deposit
based on the structure of the sulfide zone and the associated rock types. These ore deposits are created by volcanic-associated hydrothermal events in submarine environments. However, there is evidence that the sulfide mineralization does not have a volcanogenic origin. An unusual feature of this sulfide deposit is the large degree of magnetite at the actual showing. Studies have shown that the chert-magnetite iron formations in the West and North Pits of Sherman Mine extend under and along a series of small lakes from Vermillion Lake to Net Lake. These iron formations are located at roughly the same stratigraphic position as the magnetite-bearing iron formation on the southwestern shore of Net Lake. A northwest-trending cross fault is accompanied by drag folding of a chert-magnetite iron formation unit southeast of Cooke Lake. Also exposed in this area is a dark yellow 40 cm (15.7 in) wide quartz vein composed of pyrite that cross cuts the iron formation at the northeastern end. This west-northwest trending quartz vein is about long.
Layered chert-magnetite and lesser chert-pyrite-pyrrhotite iron formations are located at the base of the Arsenic Lake Formation. Former drilling near Vermillion Lake and spatial relationships observed on the surface, suggest that the sulfide-rich iron formation lies up to stratigraphically under the oxide facies iron formation. Iron production from the West and North Pits of Sherman Mine came from this chert-magnetite iron formation unit while chert-magnetite iron formations at the South and East Pits compose the Turtle Lake Formation. The South and East Pit iron formations reach thicknesses of and overlie a thinly bedded turbidite package on the southern limb of the Tetapaga Syncline.
A white palladium mercury
telluride
mineral known as temagamite
was discovered in 1973 on Temagami Island
in Lake Temagami. It is present as microscopic inclusions within chalcopyrite in association with other rare tellurides, such as merenskyite
, stuetzite and hessite
. Also discovered on the island was an unnamed palladium mercury silver
telluride mineral, the composition and optical properties of which are significantly different from those of temagamite.
Kenorland
between 2.8 and 2.6 billion years ago. This large landmass consisted of the Baltic
and Siberian shields
of Eurasia
and Archean provinces
of North America, including the Superior craton of which the Temagami belt occupies a part. Rift
ing of Kenorland began 2.45 billion years ago in Ontario with the formation of several large igneous province
s. Initial rifting is represented by basal mafic volcanic rocks in the nearby Huronian Supergroup. Final breakup formed a large group of mafic dike
and sill swarm
s in the North American provinces 2.2–2.1 billion years ago. By the Paleoproterozoic
era Kenorland had already rifted apart, and the Temagami greenstone belt formed a small part of the supercontinent Columbia
starting 1.9–1.8 billion years ago. Eastern India, Australia, Laurentia
, Baltica
, North China, the Amazon shield and portions of Antarctica formed the landmass until it ruptured 1.5–1.4 billion years ago. In the late Mesoproterozoic
era 1.1 billion years ago, the Temagami belt was part of another supercontinent. This former supercontinent, known as Rodinia
, included Oaxaquia, Rockall, Laurentia, Baltica, Australia, West Africa
, South China
, Amazonia, Mawson and Rio de la Plata
cratons, as well as the Pampean terrane. Laurentia, which included the Superior craton and the Temagami greenstone belt, is interpreted to have formed the core of Rodinia because it is surrounded by passive margins formed during the breakup of the supercontinent some 750 million years ago.
After Rodinia broke apart, its southern half traveled south and crossed the South Pole
while its northern half traveled northward to the North Pole
. The two halves of Rodinia eventually collided with the Congo craton
to form the supercontinent Pannotia
600 million years ago. In contrast to Rodinia, Pannotia was short-lived. It rifted apart 545 million years ago, or only 65 million years after it formed. This resulted in the creation of at least four continents, namely Baltica, Siberia
, Gondwana
and Laurentia. By the Early Cambrian 514 million years ago, Laurenta was located on the equator
, Baltica was south of Laurenta, Siberia was just south of the equator east of Laurenta, and Gondwana lied mostly in the Southern Hemisphere
. Subsequently, Baltica, Laurenta and microcontinent Avalonia
collided in the Devonian
period (416-359 million years ago) to form minor supercontinent Euramerica
. This eventually started to collide with Gondwana and other landmasses to form supercontinent Pangaea
255 million years ago. In the Late Triassic
period some 152 million years ago, Pangaea split into two minor supercontinents, namely Gondwana and Laurasia
. The Temagami greenstone belt represented a minor portion of western Laurasia until it divided into Eurasia and North America about 94 million years ago. Since the Middle Miocene
14 million years ago, the Temagami greenstone belt has been part of the Americas
, a minor north-south trending supercontinent comprising the continents of North America and South America
.
for a spelling reform
to Temagami at the instigation of the general public. The Executive Secretary of this committee subsequently applied to the Lands and Surveys Branch of the Ontario Department of Lands and Forests. This former department, now part of Ministry of Natural Resources
, corresponded with the proposed renaming of Timagami on March 20, 1968, as well as for Lake Timagami, Timagami Island and the Timagami River. Further improvements occurred when the Geographical Names Board of Canada agreed to change the name spelling to Temagami on March 27, 1968. Nevertheless the original spelling (Timagami) has appeared in documents published after the renaming, including Kent C. Condie's 1981 book Archean Greenstone Belts.
At least five explorations took place in the Strathy Township property before 1995. In 1934 Strathy Basin and Erie Canadian Mines conducted prospected sections of the 1995 claim block. A wide rusted zone within a dike was announced as containing values of $7.50 combined gold, copper and nickel
. Little work has been completed in this area. In 1959 and 1960, Goldfields Mining conducted a basic airborne electromagnetic survey and magnetic survey over the property. Several holes were drilled and intersected mostly mafic to intermediate volcanic rocks and areas of stringer sulfides with pyrrhotite, pyrite and some chalcopyrite. No assays were reported. In 1970 E. L. McVeigh occupied a section of the property, including the area that was once owned by Strathy Basin Mines. McVeigh conducted geophysical surveys over Strathy Basin's mineralized zone and announced no conductors. From 1974 to 1975 Vale Limited owned an extensive section of the Strathy Township property. They conducted magnetic and electromagnetic surveys, as well as mapping and drilling. Vale announced that they intersected mineralized sulfide zones ranging from to thick.
In 1952 Rib Lake Copper Mines explored areas adjacent to Whitney Lake and between Whitney Lake and Rib Lake
, by creating trenches and carrying out diamond drilling. Nickel was discovered with widespread pyrrhotite in sheared mafic rocks. Gold mineralization was discovered with pyrite in slightly siliceous tuff. The highest assessment was of gold per ton and 0.99% of nickel over , both from the same zone. Detailed work did not occur in the Rib Lake area of southern Gillies Limit Township and northern Best Township until 1968, when mapping took place, but it is unclear whether volcanic rocks in the Rib Lake area are part of the Temagami greenstone belt, as they have not been mapped in any detail. With the existence of Early Archean age tholeiitic and/or calc-alkaline mafic to intermediate volcanic rocks, they may represent a minor continuation of the belt, which is located about to the southwest. Small intrusions and pyroclastics of mafic composition are also present in the area. In 1956 Silanco carried out geophysics south of Whitney Lake. In 1964 Nickel Rim Mines Ltd. had a greatest result of of gold per ton. The exploration and mining activity south of Gillies Limit Township observed nickel, copper and platinum group metals at Cuniptau Mine and gold, silver and copper at the Big Dan and Little Dan mines.
announced that they would be closing the mine. The municipality of Temagami made several approaches to Dofasco before the closer of Sherman Mine, offering a partnership in the community's future in terms of shared funding for a Sherman Park. However, it was informed during discussions with Dofasco's media executives that in the future they could not be counted on for maintenance funds for parks or anything else that was being done in partnership with the community. This caused a large attitudinal change from a few months earlier when the mine was associated with much of Temagami. The closure also had a significant impact on the economy of Temagami. There is still iron ore at Sherman Mine, but Dofasco were able to obtain it more cheaply elsewhere.
The Kanichee Mine property, formerly known as Cuniptau Mine, was first discovered in the early 1900s just before World War I began. A mine shaft with of underground lateral workings was completed on two levels in 1934. At least 11 mine claims occupied the area at the time. The core of a widespread massive sulfide deposit composed of palladium, nickel, copper, gold, cobalt, platinum and silver was mined out from underground and by an open pit from 1934 to 1936. Since 1938, at least seven different ownerships have held the Kanichee Mine property. Subsequent mining from 1974 to 1975 increased the size of the open pit and removed the shaft pillar. The open pit and underground workings have remain flooded since the mine closed in the 1970s.
Copperfields Mine, originally known as Temagami Mine, extracted both base
and precious metal
s on Temagami Island in Lake Temagami from March 1955 until its closer in February 1972. A 200 ton mill refined ore from two open pits and underground workings off a mine shaft. For the first few years after the mine opened, ore trucks were barged down the northeastern arm of Lake Temagami to the town of Temagami, but this soon proved to be too expensive. The result was to create a gravel road from Highway 11 to the eastcentral shore of Lake Temagami. This road, now known as the Lake Temagami Access Road, was completed in 1958 and was used to transport ore from the mine site. The high-grade copper deposit in which the mine extracted was discovered by Canadian geophysicist Norman Bell Keevil (1910–1989) in the mid-20th century during testing of a newly established airborne metal detector
. It was the largest deposit of nearly pure chalcopyrite ever discovered in Canada. Keevil also financed other ventures, including what became Teck Resources. By February 1972, the Copperfields mill had treated of gold, of silver and of copper.
Along the southeastern margin of the Net Lake-Vermilion Lake Deformation Zone lies the abandoned Beanland Mine
property. Exploration work in 1937–1938 resulted in the creation of a three level mine shaft. In February 1992, Deak Resources completed diamond drilling and bulk sampling at the mine and 3,000 tons of rock was shipped to its Kerr Mill in Virginiatown. The estimated reserves, before this work, were 8,778 tons averaging of gold per ton across a mining width and 24,000 tons averaging of gold per ton across a mining width. The mineralized zone is described as a quartz vein network, enveloped by alteration in tholeiitic basalts, paralleling the Net Lake-Vermilion Lake Deformation Zone.
About north of Beanland lies the abandoned Hermiston-McCauley Mine, situated on the northwestern side of the Net Lake-Vermilion Lake Deformation Zone. From 1935 to 1940, a three-compartment mine shaft was constructed. Three levels were created, two of which had of lateral work. Reserves have been variously estimated at 31,000 tons averaging of gold per ton, 45,700 tons averaging of gold per ton over , or 9,000 tons averaging 0.5 oz (14.2 g) of gold per ton over . A main and subsidiary quartz-rich zone occur in a ruptured intrusion composed of diorite, which intrudes felsic volcanic rocks in a northwesterly direction with the strike of the Net Lake-Vermilion Lake Deformation Zone. The main vein is at least long and up to wide. Pyrite with chalcopyrite and gold occupies the quartz-rich zones as blebs and small veins.
Mining operations began at Leckie Mine
, a now abandoned gold mine north of the Temagami, in the early 1900s with the construction of a mine shaft with of underground workings. In 1909 about 270 tons of ore was shipped out of the shaft. A mine shaft with five levels was constructed during a second period of exploration from 1930 to 1948. About of drifting and crosscutting was completed on all five levels.
Production continued at the Big Dan Occurrences during the early 20th century. Two shallow mine shafts were created in 1906 and were used to ship ore out of the mine. At least of gold per ton was sent during this period. The mine was constructed in a , north striking mineralized portion of the Big Dan Shear Zone.
Greenstone belt
Greenstone belts are zones of variably metamorphosed mafic to ultramafic volcanic sequences with associated sedimentary rocks that occur within Archaean and Proterozoic cratons between granite and gneiss bodies....
in the Temagami region of Northeastern Ontario
Northeastern Ontario
Northeastern Ontario is the region within the Canadian province of Ontario which lies north and east of Lakes Superior and Huron.Northeastern Ontario consists of the districts of Algoma, Sudbury, Cochrane, Timiskaming, Nipissing and Manitoulin; and the single-tier municipality of Greater...
, Canada. It represents a feature of the Superior craton
Superior craton
The Superior craton forms the core of the Canadian Shield at the heart of the North American continent. It extends from Quebec in the east to eastern Manitoba in the west...
, an ancient and stable part of the Earth's lithosphere
Lithosphere
The lithosphere is the rigid outermost shell of a rocky planet. On Earth, it comprises the crust and the portion of the upper mantle that behaves elastically on time scales of thousands of years or greater.- Earth's lithosphere :...
that forms the core of the North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
n continent
Continent
A continent is one of several very large landmasses on Earth. They are generally identified by convention rather than any strict criteria, with seven regions commonly regarded as continents—they are : Asia, Africa, North America, South America, Antarctica, Europe, and Australia.Plate tectonics is...
and Canadian Shield
Canadian Shield
The Canadian Shield, also called the Laurentian Plateau, or Bouclier Canadien , is a vast geological shield covered by a thin layer of soil that forms the nucleus of the North American or Laurentia craton. It is an area mostly composed of igneous rock which relates to its long volcanic history...
. The belt is composed of metamorphosed
Metamorphism
Metamorphism is the solid-state recrystallization of pre-existing rocks due to changes in physical and chemical conditions, primarily heat, pressure, and the introduction of chemically active fluids. Mineralogical, chemical and crystallographic changes can occur during this process...
volcanic rock
Volcanic rock
Volcanic rock is a rock formed from magma erupted from a volcano. In other words, it is an igneous rock of volcanic origin...
s that range in composition from basalt
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...
to rhyolite
Rhyolite
This page is about a volcanic rock. For the ghost town see Rhyolite, Nevada, and for the satellite system, see Rhyolite/Aquacade.Rhyolite is an igneous, volcanic rock, of felsic composition . It may have any texture from glassy to aphanitic to porphyritic...
. These form the east-northeast trend of the belt and are overlain by metamorphosed sedimentary rock
Sedimentary rock
Sedimentary rock are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate from a solution....
s. They were created during several volcanic episodes involving a variety of eruptive styles ranging from passive lava eruptions
Effusive eruption
An effusive eruption is a volcanic eruption characterized by the outpouring of lava onto the ground...
to viscous explosive eruption
Explosive eruption
An explosive eruption is a volcanic term to describe a violent, explosive type of eruption. Mount St. Helens in 1980 was an example. Such an eruption is driven by gas accumulating under great pressure. Driven by hot rising magma, it interacts with ground water until the pressure increases to the...
s.
Part of the Canadian Shield, the Temagami greenstone belt contains some of the oldest known rocks on Earth. The belt is made up of a number of geologic features such as batholith
Batholith
A batholith is a large emplacement of igneous intrusive rock that forms from cooled magma deep in the Earth's crust...
s, stocks, dikes
Dike (geology)
A dike or dyke in geology is a type of sheet intrusion referring to any geologic body that cuts discordantly across* planar wall rock structures, such as bedding or foliation...
, volcanic complexes, layered intrusions and deformation zones. These are situated in several geographical townships
Township (Canada)
The term township generally means the district or area associated with a town. However in some systems no town needs to be involved. The specific use of the term to describe political subdivisions has varied by country, usually to describe a local rural or semi-rural government within the county...
in the municipality of Temagami, including Chambers, Strathy
Strathy Township
Strathy Township is a square-shaped geographic township comprising a portion of the municipality of Temagami in Northeastern Ontario, Canada. It is used for geographic purposes, such as land surveying and natural resource explorations...
, Strathcona, Briggs and possibly Best.
Geology
Geologists assume that greenstone belts were formed by many geological processes, such as tectonism, magmaMagma
Magma is a mixture of molten rock, volatiles and solids that is found beneath the surface of the Earth, and is expected to exist on other terrestrial planets. Besides molten rock, magma may also contain suspended crystals and dissolved gas and sometimes also gas bubbles. Magma often collects in...
tism, metamorphism and sedimentation
Sedimentation
Sedimentation is the tendency for particles in suspension to settle out of the fluid in which they are entrained, and come to rest against a barrier. This is due to their motion through the fluid in response to the forces acting on them: these forces can be due to gravity, centrifugal acceleration...
. They are important economically for large metal deposits, and for the insight they provide into crustal
Crust (geology)
In geology, the crust is the outermost solid shell of a rocky planet or natural satellite, which is chemically distinct from the underlying mantle...
evolution and the tectonics
Tectonics
Tectonics is a field of study within geology concerned generally with the structures within the lithosphere of the Earth and particularly with the forces and movements that have operated in a region to create these structures.Tectonics is concerned with the orogenies and tectonic development of...
of the early Earth. The Temagami greenstone belt is wide and long. It contains the southernmost remnants of Archean
Archean
The Archean , also spelled Archeozoic or Archæozoic) is a geologic eon before the Paleoproterozoic Era of the Proterozoic Eon, before 2.5 Ga ago. Instead of being based on stratigraphy, this date is defined chronometrically...
intrusive and supracrustal rock
Supracrustal rock
Supracrustal rocks are rocks that were deposited on the existing basement rocks of the crust, hence the name. They may be further metamorphosed from both sedimentary and volcanic rocks....
s in Eastern Ontario
Eastern Ontario
Eastern Ontario is a subregion of Southern Ontario in the Canadian province of Ontario which lies in a wedge-shaped area between the Ottawa River and St. Lawrence River...
, as well as some of the most ancient felsic
Felsic
The word "felsic" is a term used in geology to refer to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium....
magmatic events in this section of the Superior craton. Uranium-lead dating
Uranium-lead dating
Uranium-lead is one of the oldest and most refined of the radiometric dating schemes, with a routine age range of about 1 million years to over 4.5 billion years, and with routine precisions in the 0.1-1 percent range...
has established that the Iceland Lake Pluton
Iceland Lake Pluton
The Iceland Lake Pluton, formerly known as the Ingall Lake Batholith, is a large granitic intrusion in Briggs and Strathcona townships of Temagami, Northeastern Ontario, Canada. It is one the three separate granitoid intrusions that constitute the Temagami greenstone belt, consisting of rocks...
, as well as an adjacent rhyolitic lava flow, is about 2,736 million years old. Therefore at least some intrusion
Intrusion
An intrusion is liquid rock that forms under Earth's surface. Magma from under the surface is slowly pushed up from deep within the earth into any cracks or spaces it can find, sometimes pushing existing country rock out of the way, a process that can take millions of years. As the rock slowly...
s were likely formed during the first volcanic phases in the belt and may have been conduits for volcanic eruptions.
The variety of volcanic deposits and intrusions in the Temagami greenstone belt indicates that magmatic activity played a significant part in its formation. Pillow lava
Pillow lava
Pillow lavas are lavas that contain characteristic pillow-shaped structures that are attributed to the extrusion of the lava under water, or subaqueous extrusion. Pillow lavas in volcanic rock are characterized by thick sequences of discontinuous pillow-shaped masses, commonly up to one metre in...
is found throughout the belt, indicating lava erupted underwater. Its pyroclastic deposits
Pyroclastic rock
Pyroclastic rocks or pyroclastics are clastic rocks composed solely or primarily of volcanic materials. Where the volcanic material has been transported and reworked through mechanical action, such as by wind or water, these rocks are termed volcaniclastic...
are remnants of explosive volcanism
Volcanism
Volcanism is the phenomenon connected with volcanoes and volcanic activity. It includes all phenomena resulting from and causing magma within the crust or mantle of a planet to rise through the crust and form volcanic rocks on the surface....
. The oldest exposed rocks within the belt are fine to medium-grained basalts and andesite
Andesite
Andesite is an extrusive igneous, volcanic rock, of intermediate composition, with aphanitic to porphyritic texture. In a general sense, it is the intermediate type between basalt and dacite. The mineral assemblage is typically dominated by plagioclase plus pyroxene and/or hornblende. Magnetite,...
s. Lava flow units range in thickness from to . Mafic agglomerate
Agglomerate
Agglomerates are coarse accumulations of large blocks of volcanic material that contain at least 75% bombs...
and breccia
Breccia
Breccia is a rock composed of broken fragments of minerals or rock cemented together by a fine-grained matrix, that can be either similar to or different from the composition of the fragments....
are relatively abundant, being either massive and undeformed, or sheared. Dacitic lava flows or tuff
Tuff
Tuff is a type of rock consisting of consolidated volcanic ash ejected from vents during a volcanic eruption. Tuff is sometimes called tufa, particularly when used as construction material, although tufa also refers to a quite different rock. Rock that contains greater than 50% tuff is considered...
s overlie these metamorphosed volcanic rocks along with intermediate
Intermediate composition
In igneous petrology an intermediate composition refers to the chemical composition of a rock that has 52-63 wt% SiO2 being an intermediate between felsic and mafic compositions. Typical intermediate rocks include andesite, dacite and trachyandesite among volcanic rocks and diorite and granodiorite...
volcanic breccias, and are overlain by rhyolite lava flows and tuffs. Acidic lava flow units range in thickness from to and are common in the Vermilion Lake and Link Lake areas. The felsic tuffs are normally altered and sheared. The most recent intrusive activity in the Temagami greenstone belt was the formation of a rhyolite porphyry dike million years ago. This age correlates well with the 2675–2700 million year old intrusions throughout the Abitibi Subprovince, but the 2736 million year old magmatic events in the Temagami greenstone belt are older than the closest exposed portion of the Abitibi Subprovince, about north of Kirkland Lake.
Along with nearby granitic intrusions, the Temagami greenstone belt is bounded by layers of rock comprising the Huronian Supergroup
Huronian Supergroup
The Huronian Supergroup is a Proterozoic geologic feature of the Superior craton of the Canadian Shield in Ontario and Quebec. It extends from the city of Sault Ste. Marie in the west to the Ontario-Quebec border to the east....
. Strathy Township is dominated by metamorphosed volcanic rocks of the northeastern portion of the belt. It is approximately north of the Grenville Front Tectonic Zone
Grenville Front Tectonic Zone
The Grenville Front Tectonic Zone is a geological feature in Eastern Canada that separates the Superior craton from rocks of the Grenville orogeny. It is a large tectonic zone of the Canadian Shield, extending from the northern shore of Lake Huron through Ontario and Quebec to Labrador, a distance...
. The volcanic rocks possibly total as much as thick. However, portions of the sequence might have been repeatedly sheared by one or several local fault zones. Every large volcanic event is capped by metamorphosed sedimentary rocks and/or iron formations
Banded iron formation
Banded iron formations are distinctive units of sedimentary rock that are almost always of Precambrian age. A typical BIF consists of repeated, thin layers of iron oxides, either magnetite or hematite , alternating with bands of iron-poor shale and chert...
. The metamorphosed sedimentary units range in thickness from to and consist of laminated slate
Slate
Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism. The result is a foliated rock in which the foliation may not correspond to the original sedimentary layering...
and greywacke
Greywacke
Greywacke or Graywacke is a variety of sandstone generally characterized by its hardness, dark color, and poorly sorted angular grains of quartz, feldspar, and small rock fragments or lithic fragments set in a compact, clay-fine matrix. It is a texturally immature sedimentary rock generally found...
with or without volcanogenic tuffs. The iron formations are composed of alternate layers of magnetite
Magnetite
Magnetite is a ferrimagnetic mineral with chemical formula Fe3O4, one of several iron oxides and a member of the spinel group. The chemical IUPAC name is iron oxide and the common chemical name is ferrous-ferric oxide. The formula for magnetite may also be written as FeO·Fe2O3, which is one part...
, white quartzite
Quartzite
Quartzite is a hard metamorphic rock which was originally sandstone. Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression within orogenic belts. Pure quartzite is usually white to gray, though quartzites often occur in various shades of pink...
, jasper
Jasper
Jasper, a form of chalcedony, is an opaque, impure variety of silica, usually red, yellow, brown or green in color; and rarely blue. This mineral breaks with a smooth surface, and is used for ornamentation or as a gemstone. It can be highly polished and is used for vases, seals, and at one time for...
, grey chert
Chert
Chert is a fine-grained silica-rich microcrystalline, cryptocrystalline or microfibrous sedimentary rock that may contain small fossils. It varies greatly in color , but most often manifests as gray, brown, grayish brown and light green to rusty red; its color is an expression of trace elements...
y quartz, and/or tremolite
Tremolite
Tremolite is a member of the amphibole group of silicate minerals with composition: Ca2Mg5Si8O222. Tremolite forms by metamorphism of sediments rich in dolomite and quartz. Tremolite forms a series with actinolite and ferro-actinolite. Pure magnesium tremolite is creamy white, but the color grades...
-chlorite
Chlorite group
The chlorites are a group of phyllosilicate minerals. Chlorites can be described by the following four endmembers based on their chemistry via substitution of the following four elements in the silicate lattice; Mg, Fe, Ni, and Mn....
tuff. They are intruded by sills
Sill (geology)
In geology, a sill is a tabular sheet intrusion that has intruded between older layers of sedimentary rock, beds of volcanic lava or tuff, or even along the direction of foliation in metamorphic rock. The term sill is synonymous with concordant intrusive sheet...
composed of medium-grained, white-weathering, quartz diorite
Quartz diorite
Quartz diorite is an igneous, plutonic rock, of felsic composition, with phaneritic texture. Feldspar is present as plagioclase with 10% or less potassium feldspar. Quartz is present at between 5 to 20% of the rock. Biotite, amphiboles and pyroxenes are common dark accessory...
that range in thickness from to . These rocks are similar to the coarse thicker parts of lava flows, but are interpreted to be partly intrusive, likely conduits that produced mafic volcanism.
Intrusions
A layered intrusion composed of diorite, pyroxenitePyroxenite
Pyroxenite is an ultramafic igneous rock consisting essentially of minerals of the pyroxene group, such as augite and diopside, hypersthene, bronzite or enstatite. They are classified into clinopyroxenites, orthopyroxenites, and the websterites which contain both pyroxenes...
, gabbro
Gabbro
Gabbro refers to a large group of dark, coarse-grained, intrusive mafic igneous rocks chemically equivalent to basalt. The rocks are plutonic, formed when molten magma is trapped beneath the Earth's surface and cools into a crystalline mass....
and anorthositic gabbro has been found in northwestern Strathy Township. Pyrrhotite
Pyrrhotite
Pyrrhotite is an unusual iron sulfide mineral with a variable iron content: FeS . The FeS endmember is known as troilite. Pyrrhotite is also called magnetic pyrite because the color is similar to pyrite and it is weakly magnetic...
is common in associated pyroclastic rock
Pyroclastic rock
Pyroclastic rocks or pyroclastics are clastic rocks composed solely or primarily of volcanic materials. Where the volcanic material has been transported and reworked through mechanical action, such as by wind or water, these rocks are termed volcaniclastic...
. Several northeast-trending shear zone
Shear zone
A shear zone is a very important structural discontinuity surface in the Earth's crust and upper mantle. It forms as a response to inhomogeneous deformation partitioning strain into planar or curviplanar high-strain zones. Intervening blocks stay relatively unaffected by the deformation...
s less than wide intersect the edifice, extending along the Net Lake-Vermilion Lake Deformation Zone
Net Lake-Vermilion Lake Deformation Zone
The Net Lake-Vermilion Lake Deformation Zone, also known as the Net Lake-Vermilion Lake Zone of Deformation, is a zone of deformation in Temagami, Ontario, Canada, extending from Vermilion Lake to Net Lake in a northeasterly direction.-See also:...
. This layered intrusion might be similar in age to the Kanichee layered intrusive complex
Kanichee layered intrusive complex
The Kanichee layered intrusive complex, also called the Kanichee intrusion and Ajax intrusion, is a layered intrusion in Northwestern Ontario, Canada, located in the central portion of Strathy Township about northwest of the town of Temagami...
, and may represent a magma chamber
Magma chamber
A magma chamber is a large underground pool of molten rock found beneath the surface of the Earth. The molten rock in such a chamber is under great pressure, and given enough time, that pressure can gradually fracture the rock around it creating outlets for the magma...
that was the source of tholeiitic volcanic activity.
The Kanichee layered intrusive complex, also known as the Kanichee Intrusion and Ajax Intrusion, is the most voluminous mafic-ultramafic body in metamorphosed felsic and mafic volcanic rocks of the northern Temagami greenstone belt. It is an oval-shaped layered intrusion that was formed during five phases of magmatic activity. A series of south-southeast dipping cyclic magmatic layers make up the intrusion, similar to those of the surrounding metamorphosed volcanic rocks, indicating that the rocks of the intrusion were formed horizontally and likely close to the surface. Numerous magmatic events may have breached the surface to produce volcanic eruptions. The overall structure of the intrusion indicates it is cylindrical in shape and has a long axis plunging to the southeast at a somewhat steep angle. Its fairly steep angled axis was formed by at least one period of deformation that similarly folded and deformed the surrounding volcanic rocks.
An intrusion of light-coloured diorite lies at the northern end of the Tetapaga Syncline
Tetapaga Syncline
The Tetapaga Syncline, also known as the Lake Tetapaga Syncline, is a northeasterly trending syncline in Northeastern Ontario, Canada, located in Strathy Township of the municipality of Temagami. It represents a major structural feature in the Temagami greenstone belt, with dark green, massive and...
, along the Milne-Sherman Road. Its colouration is from weathering of plagioclase
Plagioclase
Plagioclase is an important series of tectosilicate minerals within the feldspar family. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a solid solution series, more properly known as the plagioclase feldspar series...
, which comprises more than 50% of the intrusive rock. Several east-trending high-strain zones related to the Link Lake Deformation Zone
Link Lake Deformation Zone
The Link Lake Deformation Zone, also known as the Link Lake Zone of Deformation and the Link Lake Shear Zone, is a zone of deformation in Strathy Township of Temagami, Ontario, Canada...
, less than wide, are found in the intrusion, indicating that it formed at least before the last increment of strain along the Link Lake Deformation Zone. The dioritic intrusion might be the remains of a magma chamber that was the product of calc-alkaline
Calc-alkaline
The calc-alkaline magma series is one of two main magma series in igneous rocks, the other magma series being the tholeiitic. A magma series is a series of compositions that describes the evolution of a mafic magma, which is high in magnesium and iron and produces basalt or gabbro, as it...
feldspar
Feldspar
Feldspars are a group of rock-forming tectosilicate minerals which make up as much as 60% of the Earth's crust....
-phyric felsic volcanism, the erupted products of which are mostly located in the Sherman Mine
Sherman Mine
Sherman Mine is a large abandoned open pit mine in Temagami, Ontario, Canada. It was a major producer of iron ore. The mine was the source of a multi-ton boulder of banded iron formation and was mined from 1967 until 1990 by Cleveland-Cliffs Iron Company...
area.
At least three large granitoid
Granitoid
A granitoid or granitic rock is a variety of coarse grained plutonic rock similar to granite which mineralogically are composed predominately of feldspar and quartz. Examples of granitoid rocks include granite, quartz monzonite, quartz diorite, syenite, granodiorite and trondhjemite. Many are...
intrusion
Intrusion
An intrusion is liquid rock that forms under Earth's surface. Magma from under the surface is slowly pushed up from deep within the earth into any cracks or spaces it can find, sometimes pushing existing country rock out of the way, a process that can take millions of years. As the rock slowly...
s penetrate the Temagami greenstone belt. The Spawning Lake Stock
Spawning Lake Stock
The Spawning Lake Stock is an Archean age granitoid stock in Northeastern Ontario, Canada, located in Briggs Township and Chambers Township of Temagami. It intrudes through the Tetapaga Syncline, a major geologic fold in the Temagami greenstone belt. However, it remains undeformed by strain...
in Briggs and Chambers township
Township
The word township is used to refer to different kinds of settlements in different countries. Township is generally associated with an urban area. However there are many exceptions to this rule. In Australia, the United States, and Canada, they may be settlements too small to be considered urban...
s contains megacryst
Megacryst
In geology, a megacryst is a crystal or grain that is considerably larger than the encircling matrix. They are found in igneous and metamorphic rocks.- Notes :*...
s that reach to in diameter. It shears through the nearby fold axis of the Tetapaga Syncline, but remains undeformed by the western expression of the Net Lake-Vermilion Lake Deformation Zone. To the north and northeast, the massive Chambers-Strathy Batholith was formed during one magmatic event. It consists of intrusive rocks ranging from pink to grey quartz monzonite
Quartz monzonite
Quartz monzonite is an intrusive igneous rock that has an approximately equal proportion of orthoclase and plagioclase feldspars. The plagioclase is typically intermediate to sodic in composition, andesine to oligoclase. Quartz is present in significant amounts. Biotite and/or hornblende...
to granodiorite
Granodiorite
Granodiorite is an intrusive igneous rock similar to granite, but containing more plagioclase than orthoclase-type feldspar. Officially, it is defined as a phaneritic igneous rock with greater than 20% quartz by volume where at least 65% of the feldspar is plagioclase. It usually contains abundant...
and intrudes metamorphosed volcanic rocks of the Temagami greenstone belt. The Iceland Lake Pluton, situated in Strathcona and Briggs townships, consists of a complex series of chlorite trondhjemite
Trondhjemite
Trondhjemite is a leucocratic intrusive igneous rock. It is a variety of tonalite in which the plagioclase is mostly in the form of oligoclase. Trondhjemites are sometimes known as plagiogranites....
, hornblende
Hornblende
Hornblende is a complex inosilicate series of minerals .It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole....
quartz diorite and hornblende trondhjemite magmas that were emplaced during more than one magmatic event. The trend of metamorphosed volcanic rocks in Briggs and Strathcona townships is parallel to the intrusion contact. A planar fabric
Fabric (geology)
In geology, a rock's fabric describes the spatial and geometric configuration of all the elements that make it up.-Types of fabric:* Primary fabric — a fabric created during the original formation of the rock, e.g...
, attributed to the earliest deformation of the Temagami greenstone belt, exists in the outer margin of the intrusion.
Intrusive dikes composed of quartz and feldspar-quartz porphyry are widespread in Strathy Township. All dike types were placed in the Earth's crust during the formation of the Temagami greenstone belt. At least some of these dikes may have been subvolcanic
Subvolcanic rock
A subvolcanic rock, also known as a hypabyssal rock, is an igneous rock that originates at medium to shallow depths within the crust and contain intermediate grain size and often porphyritic texture. They have textures between volcanic and plutonic rocks. Subvolcanic rocks include diabase and...
feeders that produced known calc-alkalic felsic volcanic events in the belt. Many pyroxenite dikes less than 2 m (6.6 ft) wide intrude every geologic formation in the township. A pyroxenite dike east of Highway 11 extends roughly to the north-northwest while two others, north of Arsenic Lake
Arsenic Lake (Temagami)
Arsenic Lake is a lake in the Ottawa River drainage basin in Strathy Township of Temagami, Nipissing District in Northeastern Ontario, Canada, located between the town of Temagami and Temagami North near Highway 11...
, extend to the east. This includes a dike exposed along the Kanichee Mine Road in Temagami North, where it intrudes the large granitic Chambers-Strathy Batholith. A series of northwest-trending dikes composed of diabase
Diabase
Diabase or dolerite is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. In North American usage, the term diabase refers to the fresh rock, whilst elsewhere the term dolerite is used for the fresh rock and diabase refers to altered material...
may represent extensions of the 1,250 million year old Sudbury dike swarm
Sudbury dike swarm
The Sudbury dike swarm, also called the Sudbury dikes, is a Mesoproterozoic dike swarm in northeastern Ontario, Canada. With an age of 1,238 million years, it is younger than the Sudbury Basin impact event and predates the impact event that formed Lake Wanapitei.-See also:*Volcanism of...
. This dike swarm
Dike swarm
A dike swarm or dyke swarm is a large geological structure consisting of a major group of parallel, linear, or radially oriented dikes intruded within continental crust. They consist of several to hundreds of dikes emplaced more or less contemporaneously during a single intrusive event and are...
is older than the Lake Wanapitei
Lake Wanapitei
Lake Wanapitei occupies a meteorite crater in Sudbury, Ontario, Canada. It is located near the large Sudbury meteorite crater but is not related to it....
impact crater
Impact crater
In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...
but younger than the meteorite impact that created the large Sudbury Basin
Sudbury Basin
The Sudbury Basin, also known as Sudbury Structure or the Sudbury Nickel Irruptive, is a major geologic structure in Ontario, Canada. It is the second-largest known impact crater or astrobleme on Earth, as well as one of the oldest....
crater about 1,850 million years ago. Therefore, the Temagami greenstone belt predates these two impact craters, the Sudbury crater of which is the seconed largest known impact crater on Earth.
Felsic volcanic vents
Volcanic vents composed of felsic rocks are thought to have been located at the iron-bearing Sherman Mine, the former Temagami garbage dump and adjacent to the Milne TownsiteMilne Townsite
The Milne Townsite, commonly referred to as Milnes, is an abandoned community in Strathy Township, municipality of Temagami, Nipissing District in northeastern Ontario, Canada, located on the north shore of Link Lake, just south of the Milne-Sherman Road, and about north of the town of Temagami...
. Remnants of a large volcanic vent are present west of Sherman Mine, including the existence of two felsic lava flows that outcrop between Link Lake and Turtle Lake
Turtle Lake (Temagami)
Turtle Lake is an east-west trending lake in Strathy Township, Temagami, Nipissing District in Northeastern Ontario, Canada. It lies in the Sherman Mine property between the South and East pits. It is also the location of an abandoned jack ladder along its southern shore that floated logs to the...
. The aspect of the most extensive felsic lava flow indicates that the volcanic vent they erupted from was adjacent to the western portion of Link Lake. Additionally, differentiation of facies and directions in which the lava traveled exist in course grained, resedimented conglomerate
Conglomerate (geology)
A conglomerate is a rock consisting of individual clasts within a finer-grained matrix that have become cemented together. Conglomerates are sedimentary rocks consisting of rounded fragments and are thus differentiated from breccias, which consist of angular clasts...
. This suggests that a more prominent structure, perhaps evidence of a prehistoric volcano
Sherman volcano
The Sherman volcano is a possible prehistoric volcano in the municipality of Temagami in Northeastern Ontario, Canada. Geological evidence indicates that it was located west of the abandoned Sherman Mine and lies in the Archean Temagami greenstone belt....
, existed west of Link Lake. Also, coarsest felsic volcanic fragments occur in feldspar-phyric pyroclastic deposits exposed on the Sherman Mine property, suggesting the approximate location of a volcanic vent.
Just north of the Milne Townsite lies a minor felsic volcanic vent exposed along the Milne-Sherman Road. A quartz porphyry has intruded mafic and rhyolitic lava flows and a dike of diorite. In the middle of the intrusive body, the grain size of quartz phenocryst
Phenocryst
thumb|right|300px|[[Granite]]s often have large [[feldspar|feldspatic]] phenocrysts. This granite, from the [[Switzerland|Swiss]] side of the [[Mont Blanc]] massif, has large white [[plagioclase]] phenocrysts, [[triclinic]] [[mineral]]s that give [[trapezium|trapezoid]] shapes when cut through)...
s averages roughly , but become smaller towards the edge of the intrusion. Broken fragmental rocks, interpreted to be carapace breccia, are exposed along the western margin of the intrusion. Exposed near a minor felsic lava dome
Lava dome
|250px|thumb|right|Image of the [[rhyolitic]] lava dome of [[Chaitén Volcano]] during its 2008–2009 eruption.In volcanology, a lava dome is a roughly circular mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano...
is a fine grained, quartz-phyric felsic rock that may represent a rhyolite lava flow. An igneous body, interpreted to be a subvolcanic intrusion, is exposed approximately to the northwest and might have formed during the same magmatic event as the felsic dome. Exposed along the Sherman Mine railroad west of the former Milne sawmill lumber yard is a porphyritic body composed of quartz-feldspar. It is unknown if this igneous rock is a rhyolitic lava flow or an intrusion.
Several north-trending felsic dikes, composed mainly of feldspar and quartz-feldspar, are located north of the former Temagami garbage dump. These dikes are not known to extend across the Link Lake Deformation Zone, suggesting that they might represent the feeders of a minor volcanic vent, manifest now by felsic lava flows. Because certain lithologies can be correlated through the Link Lake Deformation Zone, it is unlikely that the lack of felsic dikes south of the former town dump area is an expression of displacement along the deformation zone.
Volcanic complexes
Peridotite
A peridotite is a dense, coarse-grained igneous rock, consisting mostly of the minerals olivine and pyroxene. Peridotite is ultramafic, as the rock contains less than 45% silica. It is high in magnesium, reflecting the high proportions of magnesium-rich olivine, with appreciable iron...
and pyroxenite, which are ultramafic rocks. Just to the southeast, the Younger Volcanic Complex consists mainly of mafic volcanic rocks that form four geologic formation
Geologic formation
A formation or geological formation is the fundamental unit of lithostratigraphy. A formation consists of a certain number of rock strata that have a comparable lithology, facies or other similar properties...
s. The Arsenic Lake Formation is composed of dark green, iron-rich, massive and pillowed tholeiitic basalts. Throughout the Arsenic Lake Formation are feldspar-phyric basaltic lava flows. This type of basalt contains tabular feldspar phenocrysts that range up to in cross section. Both pillowed and massive lava flows have been known to contain coarse feldspar. Coarse feldspar-bearing, iron tholeiitic basalts are more common east of Highway 11.
A number of volcanic rocks comprise the Link Lake Formation, such as feldspar-phyric, calc-alkaline basalt and andesite lava flows and less abundant quartz and quartz-feldspar-phyric felsic lava flows. Feldspar-phyric basalt lava flows are normally pillowed. Pyroclastic deposits, quartz-phyric and feldspar-felsic rocks are also present. The largest of the less common felsic lava flows is located between Link Lake and Turtle Lake. It is 2.5 km (1.6 mi) long and less than 200 m (656.2 ft) thick. The thickest portion of this lava flow or dome is located at the western end of Link Lake, where it is likely associated with a volcanic vent. The bulk of felsic rock in the Link Lake Formation occurs as subaqueous pyroclastic flow
Pyroclastic flow
A pyroclastic flow is a fast-moving current of superheated gas and rock , which reaches speeds moving away from a volcano of up to 700 km/h . The flows normally hug the ground and travel downhill, or spread laterally under gravity...
deposits. Subearial pyroclastics are normally quartz-phyric and range up to in crosssection. Dark green subearial pyroclastics composed of chlorite and sericite
Sericite
Sericite is a fine grained mica, similar to muscovite, illite, or paragonite. Sericite is a common alteration mineral of orthoclase or plagioclase feldspars in areas that have been subjected to hydrothermal alteration typically associated with copper, tin, or other hydrothermal ore deposits...
are uncommon and have sustained preferential compression in response to shear throughout the Link Lake Deformation Zone. These dark compressed pyroclastics have been interpreted to be pumice
Pumice
Pumice is a textural term for a volcanic rock that is a solidified frothy lava typically created when super-heated, highly pressurized rock is violently ejected from a volcano. It can be formed when lava and water are mixed. This unusual formation is due to the simultaneous actions of rapid...
. Some of the subsequence pyroclastic deposits contain fragments of pyrite
Pyrite
The mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS2. This mineral's metallic luster and pale-to-normal, brass-yellow hue have earned it the nickname fool's gold because of its resemblance to gold...
and quartz, suggesting that discharged sulfide hydrothermal activity
Hydrothermal circulation
Hydrothermal circulation in its most general sense is the circulation of hot water; 'hydros' in the Greek meaning water and 'thermos' meaning heat. Hydrothermal circulation occurs most often in the vicinity of sources of heat within the Earth's crust...
took place throughout the volcanic source area.
Resedimented felsic, epiclastic and turbiditic sediments compose the Turtle Lake Formation. The base of this formation consists of a heterolithic, volcaniclastic, matrix
Matrix (geology)
The matrix or groundmass of rock is the finer grained mass of material in which larger grains, crystals or clasts are embedded.The matrix of an igneous rock consists of finer grained, often microscopic, crystals in which larger crystals are embedded. This porphyritic texture is indicative of...
-supported conglomerate unit that overlies felsic lava flows and pillowed, calc-alkaline basalts of the Link Lake Formation. Many rounded to subangular felsic and mafic volcanic fragments are known to occur in the unit, as well as rare quartz vein fragments and one fragment of white chert. The conglomerate unit passes laterally and vertically into thin bedded deposits. These thin bedded deposits are interpreted to be turbidite
Turbidite
Turbidite geological formations have their origins in turbidity current deposits, which are deposits from a form of underwater avalanche that are responsible for distributing vast amounts of clastic sediment into the deep ocean.-The ideal turbidite sequence:...
s that originated from a felsic volcanic vent at the western end of Link Lake. Many dark green, highly vesicular, iron-rich tholeiitic basalts occur in the Turtle Lake Formation, and are interbedded with thin-bedded wackes on the southern limb of the Tetapaga Syncline. The basalts are best exposed along the south shore of Turtle Lake. In some cases, the basalt vesicles are over in diameter and are now filled by white quartz.
A series of dark green, massive and pillowed iron-rich tholeiitic basalt lava flows compose an unnamed upper volcanic formation of the Younger Volcanic Complex. It is situated in the core of the Tetapaga Syncline. Not much is known about this volcanic formation because only a small portion of it remains exposed in western Strathy Township.
Deformation zones
Many north-trending shear zones intersect iron-rich tholeiitic basalts of the Arsenic Lake Formation. These zones range in width from less than 1 m (3.3 ft) up to , and might maintain a larger area of weakness that was tectonically active over the past billion years. Evidence for early tectonism, likely related to volcanic activity, include the greater density of felsic dikes concentrated immediately around these zones. An example is the north-south trending Big Dan Shear ZoneBig Dan Shear Zone
The Big Dan Shear Zone is a north-south trending shear zone in Northeastern Ontario, Canada, located in the municipality of Temagami....
situated near the former garbage dump of Temagami. The felsic dikes near this zone are interpreted to represent a subvolcanic feeder system to the overlying felsic volcanic rocks. It is probable that the dikes maintained a former zone of weakness now demonstrated by the shear zones. Renewed tectonic activity along the Big Dan Shear Zone is manifested by offset of clastic sediments east of the Ontario Northland Railway
Ontario Northland Railway
The Ontario Northland Railway is a Canadian railway operated by the Ontario Northland Transportation Commission, a provincial Crown agency of the government of Ontario....
. This phase of tectonic activity displaced felsic dikes north of the exposed part of this shear zone. However, considerable displacement of the dikes at this location is unknown. The most recent phase of tectonic activity along the Big Dan Shear Zone resulted in the displacement of a Proterozoic
Proterozoic
The Proterozoic is a geological eon representing a period before the first abundant complex life on Earth. The name Proterozoic comes from the Greek "earlier life"...
dike composed of diabase, which intersects the zone. A similar abundance of felsic dikes are adjacent to Arsenic Lake just west of Highway 11, indicating similar repetitive tectonism also occurred along that structural zone. Therefore the north-trending shear zones may have been active for at least a billion years.
Extending from Net Lake
Net Lake
Net Lake is located within the municipality of Temagami, in the Nipissing District, Ontario, Canada. It covers a length of 10 km and is located in Temagami North. Fish in the lake include walleye, northern pike, trout, smallmouth bass, whitefish and panfish. There is only one lodge on Net...
to Vermilion Lake lies a northeast-southwest trending high strain zone known as the Net Lake-Vermilion Lake Deformation Zone. Because geologic mapping has not been done comprehensively throughout this zone, its exact width is unknown. The expression of this deformation zone is clearly identifiable by the intense change in volcanic rocks of the Temagami greenstone belt. Volcanic units comprising the northwestern portion of the shear zone have shifted to the northeast while the volcanic rocks comprising its southeastern portion have shifted to the southwest. Along the northeastern arm of Lake Temagami
Lake Temagami
Lake Temagami, formerly spelt as Lake Timagami, is a lake in Nipissing District in northeastern Ontario, Canada, situated approximately 80 km north of North Bay...
in Strathcona Township lies the Northeast Arm Deformation Zone
Northeast Arm Deformation Zone
The Northeast Arm Deformation Zone, also known as the Northeast Arm Zone of Deformation, is a zone of deformation in Strathcona Township of Temagami, Ontario, Canada. It extends along the northeast arm of Lake Temagami. The Link Lake Deformation Zone just to the north is interpreted to be an...
. This northeast-trending shear zone has not been studied in detail, but casual studies of many islands along the northeastern arm of Lake Temagami have shown that there is severe foliation
Foliation (geology)
Foliation is any penetrative planar fabric present in rocks. Foliation is common to rocks affected by regional metamorphic compression typical of orogenic belts. Rocks exhibiting foliation include the standard sequence formed by the prograde metamorphism of mudrocks; slate, phyllite, schist and...
and minor ferroan carbonate
Carbonate
In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group C2....
across an area about wide. The Link Lake Deformation Zone, also known as the Link Lake Shear Zone, is an area of deformation wide and over long in Strathy Township. It extends through Link Lake to east of Highway 11, but it is uncertain whether it extends west of Link Lake because no expression of it has been found in the Sherman Mine area. Therefore the Link Lake Shear Zone might be a northern extension of the Northeast Arm Deformation Zone further south. Strain intensity of the Link Lake Shear Zone is diverse. Generally, the greatest strain intensity is throughout pyroclastic rocks. Extending from the western boundary of central Chambers Township through Tasse Lake to the east is the Tasse Lake Deformation Zone
Tasse Lake Deformation Zone
The Tasse Lake Deformation Zone is a zone of deformation in Temagami, Ontario, Canada, extending from the western boundary of Chambers Township through Tasse Lake in the east...
. This deformation zone is roughly long and at least wide. It is uncertain if this deformation zone extends east of Tasse Lake.
Rock alteration
Many forms of rock alteration can be seen in the Temagami greenstone belt. Its overall structure has attained greenschistGreenschist
Greenschist is a general field petrologic term applied to metamorphic or altered mafic volcanic rock. The term greenstone is sometimes used to refer to greenschist but can refer to other rock types too. The green is due to abundant green chlorite, actinolite and epidote minerals that dominate the...
grade metamorphism, even though amphibolite
Amphibolite
Amphibolite is the name given to a rock consisting mainly of hornblende amphibole, the use of the term being restricted, however, to metamorphic rocks. The modern terminology for a holocrystalline plutonic igneous rocks composed primarily of hornblende amphibole is a hornblendite, which are...
grade metamorphism surrounds the Chambers-Strathy Batholith. The metamorphism that creates greenschist is minimal in contrast to that which creates rocks such as gneiss
Gneiss
Gneiss is a common and widely distributed type of rock formed by high-grade regional metamorphic processes from pre-existing formations that were originally either igneous or sedimentary rocks.-Etymology:...
. Other rock alterations include small veins of quartz and epidote
Epidote
Epidote is a calcium aluminium iron sorosilicate mineral, Ca2Al2O, crystallizing in the monoclinic system. Well-developed crystals are of frequent occurrence: they are commonly prismatic in habit, the direction of elongation being perpendicular to the single plane of symmetry. The faces are often...
, vesicles filled with quartz, calcite
Calcite
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate . The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.-Properties:...
and chlorite, extensive replacement of volcanic rock by silica or calcite, and calcite precipitation in extension fractures.
Outcrops of silicified mafic pillow lava are found along and west of the Ontario Northland Railway, east of the Big Dan Shear Zone and adjacent to Outlet Bay and Boot Bay of Net Lake. This form of alteration occurs in deformation zones and is the product of low temperature seawater
Seawater
Seawater is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% . This means that every kilogram of seawater has approximately of dissolved salts . The average density of seawater at the ocean surface is 1.025 g/ml...
alteration. Volcanic rock replaced by carbonate is commonly found in the Northeast Arm Deformation Zone, the Link Lake Shear Zone and in the Net Lake-Vermilion Lake Deformation Zone. Within the high strain zones, carbonate is also manifest as 1 m (3.3 ft) wide veins that have been traced along strike for more than .
Basalt has been replaced by calcite in a restricted area just north of the Temagami's former garbage dump. Although developed adjacent to the Link Lake Shear Zone, rocks within and just outside the calcite alteration zone do not normally contain significant foliation. Thus, if the calcite alteration zone was located within the Link Lake Shear Zone, it did not form inside the zone of the highest strain.
Mineralization
The Temagami greenstone belt contains massive banded iron formationBanded iron formation
Banded iron formations are distinctive units of sedimentary rock that are almost always of Precambrian age. A typical BIF consists of repeated, thin layers of iron oxides, either magnetite or hematite , alternating with bands of iron-poor shale and chert...
s and several precious metal
Precious metal
A precious metal is a rare, naturally occurring metallic chemical element of high economic value.Chemically, the precious metals are less reactive than most elements, have high lustre, are softer or more ductile, and have higher melting points than other metals...
and base metal
Base metal
In chemistry, the term base metal is used informally to refer to a metal that oxidizes or corrodes relatively easily, and reacts variably with diluted hydrochloric acid to form hydrogen. Examples include iron, nickel, lead and zinc...
deposits. The banded iron formations range from to to more than thick. Remnants of volcanic vents are an important locator for mineral
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...
potential in the Temagami belt because they are adjacent to rocks that contain certain types of mineralization
Mineralization (geology)
In geology, mineralization is the hydrothermal deposition of economically important metals in the formation of ore bodies or "lodes".The first scientific studies of this process took place in Cornwall, United Kingdom by J.W.Henwood FRS and later by R.W...
. At the Link Lake Formation, good evidence for copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
-zinc
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
massive sulfide deposits has been discovered in associated volcanic rocks. Some gold
Gold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...
mineralization may also be associated with volcanic vents. Studies of greenstone terrane
Terrane
A terrane in geology is short-hand term for a tectonostratigraphic terrane, which is a fragment of crustal material formed on, or broken off from, one tectonic plate and accreted or "sutured" to crust lying on another plate...
s in the Superior craton have shown that large gold deposits are associated with regional deformation zones. Therefore, the Northeast Arm Deformation Zone, the Link Lake Shear Zone and the Net Lake-Vermilion Lake Deformation Zone are obvious high potential areas. A number of scattered pyrite deposits can be found throughout the Northeast Arm Deformation Zone. The high frequency of gold mineralization in and near the Net Lake-Vermilion Lake Deformation Zone suggests that this deformation zone may very well also contain gold deposits; at least 11 have been discovered within a 4 km (2.5 mi) length of the deformation zone. The gold deposits are found in many rock types, indicating a stronger gold-bearing system with the potential of larger gold deposits. A number of gold-pyrite deposits exist in felsic volcanic rocks overlying the Older Volcanic Complex, near and on the northwestern part of the Net Lake-Vermilion Lake Deformation Zone. These deposits were likely formed during the creation of the Net Lake-Vermilion Lake Deformation Zone. At the Younger Volcanic Complex, gold exists in quartz veins containing base metal sulfides. It is also known to exist in pyrite associated with deformed magnetite-rich iron formations, sericitized and carbonatized felsic volcanic rock, quartz-pyrrhotite
Pyrrhotite
Pyrrhotite is an unusual iron sulfide mineral with a variable iron content: FeS . The FeS endmember is known as troilite. Pyrrhotite is also called magnetic pyrite because the color is similar to pyrite and it is weakly magnetic...
-chalcopyrite
Chalcopyrite
Chalcopyrite is a copper iron sulfide mineral that crystallizes in the tetragonal system. It has the chemical composition CuFeS2. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mohs scale. Its streak is diagnostic as green tinged black.On exposure to air, chalcopyrite...
-pentlandite
Pentlandite
Pentlandite is an iron-nickel sulfide, 9S8. Pentlandite usually has a Ni:Fe ratio of close to 1:1. It also contains minor cobalt.Pentlandite forms isometric crystals, but is normally found in massive granular aggregates. It is brittle with a hardness of 3.5 - 4 and specific gravity of 4.6 - 5.0 and...
-pyrite zones within deformation zones and in north-trending, chloritized shear zones containing arsenopyrite
Arsenopyrite
Arsenopyrite is an iron arsenic sulfide . It is a hard metallic, opaque, steel grey to silver white mineral with a relatively high specific gravity of 6.1. When dissolved in nitric acid, it releases elemental sulfur. When arsenopyrite is heated, it becomes magnetic and gives off toxic fumes...
, pyrrhotite, pyrite and chalcopyrite.
A variety of iron, copper, arsenic
Arsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...
and zinc ore
Ore
An ore is a type of rock that contains minerals with important elements including metals. The ores are extracted through mining; these are then refined to extract the valuable element....
s such as arsenopyrite, pyrrhotite, pyrite and chalcopyrite with sphalerite, are present as small veins and in quartz veins throughout north-trending shear zones that cut the iron-rich tholeiitic basalts of the Arsenic Lake Formation. Dikes composed of quartz-feldspar porphyry run parallel to or lie within the shear zones and are cut by the mineralization. Chalcopyrite occupies later fractures which intersect massive arsenopyrite. Sparse quartz veins normally exist in or adjacent to the arsenopyrite-rich zones. Several northeast-trending deformation zones intersect pyroxenite of a mafic sill in northwest Strathy Township. Within these high-strain zones quartz veins normally contain chalcopyrite, pyrite, pyrrhotite with exsolved pentlandite and traces of sphalerite and galena. Chalcopyrite, pyrrhotite and pentlandite are deposited throughout shear zones which lack quartz veining. These zones are not known to contain large amounts of gold, although investigations are incomplete. It is also unknown if platinum group
Platinum group
The platinum group metals is a term used sometimes to collectively refer to six metallic elements clustered together in the periodic table.These elements are all transition metals, lying in the d-block .The six...
metals (which include platinum
Platinum
Platinum is a chemical element with the chemical symbol Pt and an atomic number of 78. Its name is derived from the Spanish term platina del Pinto, which is literally translated into "little silver of the Pinto River." It is a dense, malleable, ductile, precious, gray-white transition metal...
, palladium
Palladium
Palladium is a chemical element with the chemical symbol Pd and an atomic number of 46. It is a rare and lustrous silvery-white metal discovered in 1803 by William Hyde Wollaston. He named it after the asteroid Pallas, which was itself named after the epithet of the Greek goddess Athena, acquired...
, rhodium
Rhodium
Rhodium is a chemical element that is a rare, silvery-white, hard and chemically inert transition metal and a member of the platinum group. It has the chemical symbol Rh and atomic number 45. It is composed of only one isotope, 103Rh. Naturally occurring rhodium is found as the free metal, alloyed...
, iridium
Iridium
Iridium is the chemical element with atomic number 77, and is represented by the symbol Ir. A very hard, brittle, silvery-white transition metal of the platinum family, iridium is the second-densest element and is the most corrosion-resistant metal, even at temperatures as high as 2000 °C...
, osmium
Osmium
Osmium is a chemical element with the symbol Os and atomic number 76. Osmium is a hard, brittle, blue-gray or blue-blacktransition metal in the platinum family, and is the densest natural element. Osmium is twice as dense as lead. The density of osmium is , slightly greater than that of iridium,...
and ruthenium
Ruthenium
Ruthenium is a chemical element with symbol Ru and atomic number 44. It is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, ruthenium is inert to most chemicals. The Russian scientist Karl Ernst Claus discovered the element...
) exist in these zones because no searches for platinum group elements have been undertaken.
Gold and copper values occupy a northeast-trending iron formation within the Net Lake-Vermilion Lake Deformation Zone. This mineralization is only known to exist southeast of Cooke Lake and immediately south of Net Lake. A unit of chert, magnetite and pyrrhotite outcrops along the southwest shore of Net Lake at Temagami North. Pyrrhotite, the most common sulfide mineral, occurs as small veins and disseminations. Small amounts of pyrite, sphalerite and exsolved pentlandite and chalcopyrite are present with the pyrrhotite. The main exposure lies immediately south of the Kanichee Mine Road, which branches off Highway 11. Minor gold and copper values constitute this zone. This sulfide-bearing unit is located within felsic volcanic rocks of the Older Volcanic Complex and is capped by large, dark green, iron-rich tholeiitic basalts of the Arsenic Lake Formation. It has been interpreted that the sulfide zone represents a volcanogenic massive sulfide ore deposit
Volcanogenic massive sulfide ore deposit
Volcanogenic massive sulfide ore deposits are a type of metal sulfide ore deposit, mainly Cu-Zn-Pb which are associated with and created by volcanic-associated hydrothermal events in submarine environments....
based on the structure of the sulfide zone and the associated rock types. These ore deposits are created by volcanic-associated hydrothermal events in submarine environments. However, there is evidence that the sulfide mineralization does not have a volcanogenic origin. An unusual feature of this sulfide deposit is the large degree of magnetite at the actual showing. Studies have shown that the chert-magnetite iron formations in the West and North Pits of Sherman Mine extend under and along a series of small lakes from Vermillion Lake to Net Lake. These iron formations are located at roughly the same stratigraphic position as the magnetite-bearing iron formation on the southwestern shore of Net Lake. A northwest-trending cross fault is accompanied by drag folding of a chert-magnetite iron formation unit southeast of Cooke Lake. Also exposed in this area is a dark yellow 40 cm (15.7 in) wide quartz vein composed of pyrite that cross cuts the iron formation at the northeastern end. This west-northwest trending quartz vein is about long.
Layered chert-magnetite and lesser chert-pyrite-pyrrhotite iron formations are located at the base of the Arsenic Lake Formation. Former drilling near Vermillion Lake and spatial relationships observed on the surface, suggest that the sulfide-rich iron formation lies up to stratigraphically under the oxide facies iron formation. Iron production from the West and North Pits of Sherman Mine came from this chert-magnetite iron formation unit while chert-magnetite iron formations at the South and East Pits compose the Turtle Lake Formation. The South and East Pit iron formations reach thicknesses of and overlie a thinly bedded turbidite package on the southern limb of the Tetapaga Syncline.
A white palladium mercury
Mercury (element)
Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...
telluride
Telluride (chemistry)
The telluride ion is Te2−. It is the final stable member of the series of dianions O2−, S2−, and Se2− ....
mineral known as temagamite
Temagamite
Temagamite is a bright white palladium mercury telluride mineral with a hardness of 2½ on the Mohs scale. Its chemical formula is Pd3HgTe3. It was discovered at the Temagami Mine on Temagami Island, Lake Temagami in 1973, and it represents a rare mineral in the Temagami greenstone belt.It occurs as...
was discovered in 1973 on Temagami Island
Temagami Island
Temagami Island, formerly spelt as Timagami Island, is an island in Lake Temagami in Northeastern Ontario, Canada. It is the largest island within the lake, with Bear Island coming second. The island has many hiking trails that lead into the old-growth forest that is a mix of large white and red...
in Lake Temagami. It is present as microscopic inclusions within chalcopyrite in association with other rare tellurides, such as merenskyite
Merenskyite
Merenskyite is a rare telluride / bismuthinide mineral with formula: 2. It is an opaque white to light gray metallic mineral that occurs as inclusions within other minerals such as chalcopyrite...
, stuetzite and hessite
Hessite
Hessite is a mineral form of disilver telluride . It is a soft, dark grey telluride mineral which forms monoclinic crystals.It is named after Germain Henri Hess ....
. Also discovered on the island was an unnamed palladium mercury silver
Silver
Silver is a metallic chemical element with the chemical symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal...
telluride mineral, the composition and optical properties of which are significantly different from those of temagamite.
Paleogeology
The Temagami greenstone belt, at 2.7 billion years old, dates back to the formation of the supercontinentSupercontinent
In geology, a supercontinent is a landmass comprising more than one continental core, or craton. The assembly of cratons and accreted terranes that form Eurasia qualifies as a supercontinent today.-History:...
Kenorland
Kenorland
Kenorland was one of the earliest supercontinents on Earth. It is believed to have formed during the Neoarchaean Era ~2.7 billion years ago by the accretion of Neoarchaean cratons and the formation of new continental crust...
between 2.8 and 2.6 billion years ago. This large landmass consisted of the Baltic
Baltic Shield
The Baltic Shield is located in Fennoscandia , northwest Russia and under the Baltic Sea. The Baltic Shield is defined as the exposed Precambrian northwest segment of the East European Craton...
and Siberian shields
Shield (geology)
A shield is generally a large area of exposed Precambrian crystalline igneous and high-grade metamorphic rocks that form tectonically stable areas. In all cases, the age of these rocks is greater than 570 million years and sometimes dates back 2 to 3.5 billion years...
of Eurasia
Eurasia
Eurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...
and Archean provinces
Geologic province
A geologic or geomorphic province is a spatial entity with common geologic or geomorphic attributes. A province may include a single dominant structural element such as a basin or a fold belt, or a number of contiguous related elements...
of North America, including the Superior craton of which the Temagami belt occupies a part. Rift
Rift
In geology, a rift or chasm is a place where the Earth's crust and lithosphere are being pulled apart and is an example of extensional tectonics....
ing of Kenorland began 2.45 billion years ago in Ontario with the formation of several large igneous province
Large igneous province
A Large Igneous Province is an extremely large accumulation of igneous rocks—intrusive, extrusive, or both—in the earth's crust...
s. Initial rifting is represented by basal mafic volcanic rocks in the nearby Huronian Supergroup. Final breakup formed a large group of mafic dike
Dike swarm
A dike swarm or dyke swarm is a large geological structure consisting of a major group of parallel, linear, or radially oriented dikes intruded within continental crust. They consist of several to hundreds of dikes emplaced more or less contemporaneously during a single intrusive event and are...
and sill swarm
Sill swarm
A sill swarm in geology is a major group of sills intruded within continental crust. They are located under volcanic edifices, including flood basalt provinces and large lava plateaus. The volume of sill swarms can be similar to dike swarms....
s in the North American provinces 2.2–2.1 billion years ago. By the Paleoproterozoic
Paleoproterozoic
The Paleoproterozoic is the first of the three sub-divisions of the Proterozoic occurring between . This is when the continents first stabilized...
era Kenorland had already rifted apart, and the Temagami greenstone belt formed a small part of the supercontinent Columbia
Columbia (supercontinent)
Columbia, also known as Nuna and Hudsonland, was one of Earth's oldest supercontinents. It was first proposed by J.J.W. Rogers and M. Santosh and is thought to have existed approximately 1.8 to 1.5 billion years ago in the Paleoproterozoic Era. Zhao et al...
starting 1.9–1.8 billion years ago. Eastern India, Australia, Laurentia
Laurentia
Laurentia is a large area of continental craton, which forms the ancient geological core of the North American continent...
, Baltica
Baltica
Baltica is a name applied by geologists to a late-Proterozoic, early-Palaeozoic continent that now includes the East European craton of northwestern Eurasia. Baltica was created as an entity not earlier than 1.8 billion years ago. Before this time, the three segments/continents that now comprise...
, North China, the Amazon shield and portions of Antarctica formed the landmass until it ruptured 1.5–1.4 billion years ago. In the late Mesoproterozoic
Mesoproterozoic
The Mesoproterozoic Era is a geologic era that occurred between 1600 Ma and 1000 Ma . The Mesoproterozoic was the first period of Earth's history with a respectable geological record. Continents existed in the Paleoproterozoic, but we know little about them...
era 1.1 billion years ago, the Temagami belt was part of another supercontinent. This former supercontinent, known as Rodinia
Rodinia
In geology, Rodinia is the name of a supercontinent, a continent which contained most or all of Earth's landmass. According to plate tectonic reconstructions, Rodinia existed between 1.1 billion and 750 million years ago, in the Neoproterozoic era...
, included Oaxaquia, Rockall, Laurentia, Baltica, Australia, West Africa
West Africa
West Africa or Western Africa is the westernmost region of the African continent. Geopolitically, the UN definition of Western Africa includes the following 16 countries and an area of approximately 5 million square km:-Flags of West Africa:...
, South China
South China (continent)
South China continent, also known as South China craton, South Chinese craton, or Yangtze craton, was an ancient continent that contained today's South and Southeast China , Indochina, and parts of Southeast Asia...
, Amazonia, Mawson and Rio de la Plata
Rio de la Plata Craton
The Río de la Plata craton is one of the five cratons of the South American continent. The other four cratons are: Amazonian, São Francisco, Río Apa and Arequipa–Antofalla.It crops out in southern Uruguay and parts of Argentina...
cratons, as well as the Pampean terrane. Laurentia, which included the Superior craton and the Temagami greenstone belt, is interpreted to have formed the core of Rodinia because it is surrounded by passive margins formed during the breakup of the supercontinent some 750 million years ago.
After Rodinia broke apart, its southern half traveled south and crossed the South Pole
South Pole
The South Pole, also known as the Geographic South Pole or Terrestrial South Pole, is one of the two points where the Earth's axis of rotation intersects its surface. It is the southernmost point on the surface of the Earth and lies on the opposite side of the Earth from the North Pole...
while its northern half traveled northward to the North Pole
North Pole
The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is, subject to the caveats explained below, defined as the point in the northern hemisphere where the Earth's axis of rotation meets its surface...
. The two halves of Rodinia eventually collided with the Congo craton
Congo craton
The Congo craton, covered by the Palaeozoic-to-recent Congo basin, is an ancient Precambrian craton that with four others makes up the modern continent of Africa. These cratons were formed between about 3.6 and 2.0 billion years ago and have been tectonically stable since that time...
to form the supercontinent Pannotia
Pannotia
Pannotia, first described by Ian W. D. Dalziel in 1997, is a hypothetical supercontinent that existed from the Pan-African orogeny about six hundred million years ago to the end of the Precambrian about five hundred and fifty million years ago. It is also known as the Vendian supercontinent...
600 million years ago. In contrast to Rodinia, Pannotia was short-lived. It rifted apart 545 million years ago, or only 65 million years after it formed. This resulted in the creation of at least four continents, namely Baltica, Siberia
Siberia (continent)
Siberia is the craton located in the heart of the region of Siberia. Siberia or "Angaraland" is today the Central Siberian Plateau...
, Gondwana
Gondwana
In paleogeography, Gondwana , originally Gondwanaland, was the southernmost of two supercontinents that later became parts of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago . Gondwana is believed to have sutured between ca. 570 and 510 Mya,...
and Laurentia. By the Early Cambrian 514 million years ago, Laurenta was located on the equator
Equator
An equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....
, Baltica was south of Laurenta, Siberia was just south of the equator east of Laurenta, and Gondwana lied mostly in the Southern Hemisphere
Southern Hemisphere
The Southern Hemisphere is the part of Earth that lies south of the equator. The word hemisphere literally means 'half ball' or "half sphere"...
. Subsequently, Baltica, Laurenta and microcontinent Avalonia
Avalonia
Avalonia was a microcontinent in the Paleozoic era. Crustal fragments of this former microcontinent underlie south-west Great Britain, and the eastern coast of North America. It is the source of many of the older rocks of Western Europe, Atlantic Canada, and parts of the coastal United States...
collided in the Devonian
Devonian
The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...
period (416-359 million years ago) to form minor supercontinent Euramerica
Euramerica
Euramerica was a minor supercontinent created in the Devonian as the result of a collision between the Laurentian, Baltica, and Avalonia cratons .300 million years ago in the Late Carboniferous tropical rainforests lay over the equator of Euramerica...
. This eventually started to collide with Gondwana and other landmasses to form supercontinent Pangaea
Pangaea
Pangaea, Pangæa, or Pangea is hypothesized as a supercontinent that existed during the Paleozoic and Mesozoic eras about 250 million years ago, before the component continents were separated into their current configuration....
255 million years ago. In the Late Triassic
Late Triassic
The Late Triassic is in the geologic timescale the third and final of three epochs of the Triassic period. The corresponding series is known as the Upper Triassic. In the past it was sometimes called the Keuper, after a German lithostratigraphic group that has a roughly corresponding age...
period some 152 million years ago, Pangaea split into two minor supercontinents, namely Gondwana and Laurasia
Laurasia
In paleogeography, Laurasia was the northernmost of two supercontinents that formed part of the Pangaea supercontinent from approximately...
. The Temagami greenstone belt represented a minor portion of western Laurasia until it divided into Eurasia and North America about 94 million years ago. Since the Middle Miocene
Middle Miocene
The Middle Miocene is a sub-epoch of the Miocene Epoch made up of two stages: the Langhian and Serravallian stages. The Middle Miocene is preceded by the Early Miocene....
14 million years ago, the Temagami greenstone belt has been part of the Americas
Americas
The Americas, or America , are lands in the Western hemisphere, also known as the New World. In English, the plural form the Americas is often used to refer to the landmasses of North America and South America with their associated islands and regions, while the singular form America is primarily...
, a minor north-south trending supercontinent comprising the continents of North America and South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
.
Naming
The name "Temagami" is Ojibwe in origin, meaning "deep clear water"; until 1968 it was spelt as "Timagami". This spelling of the name appeared on all official maps and related documents when it was adopted on June 25, 1906. In early 1968 the Canada Post Office applied to the Geographical Names Board of CanadaGeographical Names Board of Canada
Geographical Names Board of Canada is a national committee of the Canadian Government Department of Natural Resources which authorizes the names used on official federal government maps of Canada since 1897. The board consists of 27 members including one from each of the provinces and territories...
for a spelling reform
Spelling reform
Many languages have undergone spelling reform, where a deliberate, often officially sanctioned or mandated, change to spelling takes place. Proposals for such reform are also common....
to Temagami at the instigation of the general public. The Executive Secretary of this committee subsequently applied to the Lands and Surveys Branch of the Ontario Department of Lands and Forests. This former department, now part of Ministry of Natural Resources
Ministry of Natural Resources (Ontario)
The Ministry of Natural Resources is a government ministry of the Canadian province of Ontario that responsible for Ontario’s provincial parks, forests, fisheries, wildlife, mineral aggregates and the Crown lands and waters that make up 87 per cent of the province...
, corresponded with the proposed renaming of Timagami on March 20, 1968, as well as for Lake Timagami, Timagami Island and the Timagami River. Further improvements occurred when the Geographical Names Board of Canada agreed to change the name spelling to Temagami on March 27, 1968. Nevertheless the original spelling (Timagami) has appeared in documents published after the renaming, including Kent C. Condie's 1981 book Archean Greenstone Belts.
Mineral explorations
In May 1995 Pacific Mariner Exploration carried out a small drilling program on its properties in Strathy Township to estimate the likelihood of base metal deposits. A hole was drilled under Net Lake in Temagami North, but its collapse prevented the survey's completion. As a result, little is known about its geophysical features. Most of the property was influenced by Net Lake and included ten adjacent mining claims.At least five explorations took place in the Strathy Township property before 1995. In 1934 Strathy Basin and Erie Canadian Mines conducted prospected sections of the 1995 claim block. A wide rusted zone within a dike was announced as containing values of $7.50 combined gold, copper and nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
. Little work has been completed in this area. In 1959 and 1960, Goldfields Mining conducted a basic airborne electromagnetic survey and magnetic survey over the property. Several holes were drilled and intersected mostly mafic to intermediate volcanic rocks and areas of stringer sulfides with pyrrhotite, pyrite and some chalcopyrite. No assays were reported. In 1970 E. L. McVeigh occupied a section of the property, including the area that was once owned by Strathy Basin Mines. McVeigh conducted geophysical surveys over Strathy Basin's mineralized zone and announced no conductors. From 1974 to 1975 Vale Limited owned an extensive section of the Strathy Township property. They conducted magnetic and electromagnetic surveys, as well as mapping and drilling. Vale announced that they intersected mineralized sulfide zones ranging from to thick.
In 1952 Rib Lake Copper Mines explored areas adjacent to Whitney Lake and between Whitney Lake and Rib Lake
Rib Lake (Ontario)
Rib Lake is a long and narrow lake in the Town of Latchford and in the Municipality of Temagami in Northeastern Ontario, Canada, located about southeast of the centre of the community of Latchford and northeast of the community of Temagami North...
, by creating trenches and carrying out diamond drilling. Nickel was discovered with widespread pyrrhotite in sheared mafic rocks. Gold mineralization was discovered with pyrite in slightly siliceous tuff. The highest assessment was of gold per ton and 0.99% of nickel over , both from the same zone. Detailed work did not occur in the Rib Lake area of southern Gillies Limit Township and northern Best Township until 1968, when mapping took place, but it is unclear whether volcanic rocks in the Rib Lake area are part of the Temagami greenstone belt, as they have not been mapped in any detail. With the existence of Early Archean age tholeiitic and/or calc-alkaline mafic to intermediate volcanic rocks, they may represent a minor continuation of the belt, which is located about to the southwest. Small intrusions and pyroclastics of mafic composition are also present in the area. In 1956 Silanco carried out geophysics south of Whitney Lake. In 1964 Nickel Rim Mines Ltd. had a greatest result of of gold per ton. The exploration and mining activity south of Gillies Limit Township observed nickel, copper and platinum group metals at Cuniptau Mine and gold, silver and copper at the Big Dan and Little Dan mines.
Mining
Because of the high mineralization, several mines have opened in the belt. Sherman Mine, northwest of the town of Temagami, was a major producer of iron ore. Mining operations began in 1968, and workings consisted of seven open pits: North Pit, East Pit, South Pit, West Pit and three relatively small open pits known as the Turtle Pits. A railroad was built from the Ontario Northland Railway to Sherman Mine in the 1960s to make transportation and shipping of iron ore easier and faster across Ontario. To the north, Temagami North was constructed as a resource town in the 1960s to supply Sherman Mine. With an average overall grade of 25% iron, the mine produced approximately 10,700 tons of crude ore per day and its mill capacity was of iron ore pellets per year. Operations at Sherman Mine ceased in 1990 after its owner DofascoDofasco
Dofasco is a steel company based in Hamilton, Ontario, Canada, which is also home to longtime Canadian rival Stelco. Dofasco is currently a standalone subsidiary of ArcelorMittal, the world's largest steel producer. Previously ordered by the U.S...
announced that they would be closing the mine. The municipality of Temagami made several approaches to Dofasco before the closer of Sherman Mine, offering a partnership in the community's future in terms of shared funding for a Sherman Park. However, it was informed during discussions with Dofasco's media executives that in the future they could not be counted on for maintenance funds for parks or anything else that was being done in partnership with the community. This caused a large attitudinal change from a few months earlier when the mine was associated with much of Temagami. The closure also had a significant impact on the economy of Temagami. There is still iron ore at Sherman Mine, but Dofasco were able to obtain it more cheaply elsewhere.
The Kanichee Mine property, formerly known as Cuniptau Mine, was first discovered in the early 1900s just before World War I began. A mine shaft with of underground lateral workings was completed on two levels in 1934. At least 11 mine claims occupied the area at the time. The core of a widespread massive sulfide deposit composed of palladium, nickel, copper, gold, cobalt, platinum and silver was mined out from underground and by an open pit from 1934 to 1936. Since 1938, at least seven different ownerships have held the Kanichee Mine property. Subsequent mining from 1974 to 1975 increased the size of the open pit and removed the shaft pillar. The open pit and underground workings have remain flooded since the mine closed in the 1970s.
Copperfields Mine, originally known as Temagami Mine, extracted both base
Base metal
In chemistry, the term base metal is used informally to refer to a metal that oxidizes or corrodes relatively easily, and reacts variably with diluted hydrochloric acid to form hydrogen. Examples include iron, nickel, lead and zinc...
and precious metal
Precious metal
A precious metal is a rare, naturally occurring metallic chemical element of high economic value.Chemically, the precious metals are less reactive than most elements, have high lustre, are softer or more ductile, and have higher melting points than other metals...
s on Temagami Island in Lake Temagami from March 1955 until its closer in February 1972. A 200 ton mill refined ore from two open pits and underground workings off a mine shaft. For the first few years after the mine opened, ore trucks were barged down the northeastern arm of Lake Temagami to the town of Temagami, but this soon proved to be too expensive. The result was to create a gravel road from Highway 11 to the eastcentral shore of Lake Temagami. This road, now known as the Lake Temagami Access Road, was completed in 1958 and was used to transport ore from the mine site. The high-grade copper deposit in which the mine extracted was discovered by Canadian geophysicist Norman Bell Keevil (1910–1989) in the mid-20th century during testing of a newly established airborne metal detector
Metal detector
A metal detector is a device which responds to metal that may not be readily apparent.The simplest form of a metal detector consists of an oscillator producing an alternating current that passes through a coil producing an alternating magnetic field...
. It was the largest deposit of nearly pure chalcopyrite ever discovered in Canada. Keevil also financed other ventures, including what became Teck Resources. By February 1972, the Copperfields mill had treated of gold, of silver and of copper.
Along the southeastern margin of the Net Lake-Vermilion Lake Deformation Zone lies the abandoned Beanland Mine
Beanland Mine
Beanland Mine, also known as Clenore and A.E. Perron, is an abandoned gold and silver producing underground mine, located in the Temagami region of northeastern Ontario, Canada. It is one of the several mines within the Temagami greenstone belt, a volcanic belt characterized by felsic and mafic...
property. Exploration work in 1937–1938 resulted in the creation of a three level mine shaft. In February 1992, Deak Resources completed diamond drilling and bulk sampling at the mine and 3,000 tons of rock was shipped to its Kerr Mill in Virginiatown. The estimated reserves, before this work, were 8,778 tons averaging of gold per ton across a mining width and 24,000 tons averaging of gold per ton across a mining width. The mineralized zone is described as a quartz vein network, enveloped by alteration in tholeiitic basalts, paralleling the Net Lake-Vermilion Lake Deformation Zone.
About north of Beanland lies the abandoned Hermiston-McCauley Mine, situated on the northwestern side of the Net Lake-Vermilion Lake Deformation Zone. From 1935 to 1940, a three-compartment mine shaft was constructed. Three levels were created, two of which had of lateral work. Reserves have been variously estimated at 31,000 tons averaging of gold per ton, 45,700 tons averaging of gold per ton over , or 9,000 tons averaging 0.5 oz (14.2 g) of gold per ton over . A main and subsidiary quartz-rich zone occur in a ruptured intrusion composed of diorite, which intrudes felsic volcanic rocks in a northwesterly direction with the strike of the Net Lake-Vermilion Lake Deformation Zone. The main vein is at least long and up to wide. Pyrite with chalcopyrite and gold occupies the quartz-rich zones as blebs and small veins.
Mining operations began at Leckie Mine
Leckie Mine
Leckie Mine, also known as Penrose Mine, is an abandoned gold producing underground mine in Northeastern Ontario, Canada, located on the eastern shore of Arsenic Lake north of the town of Temagami...
, a now abandoned gold mine north of the Temagami, in the early 1900s with the construction of a mine shaft with of underground workings. In 1909 about 270 tons of ore was shipped out of the shaft. A mine shaft with five levels was constructed during a second period of exploration from 1930 to 1948. About of drifting and crosscutting was completed on all five levels.
Production continued at the Big Dan Occurrences during the early 20th century. Two shallow mine shafts were created in 1906 and were used to ship ore out of the mine. At least of gold per ton was sent during this period. The mine was constructed in a , north striking mineralized portion of the Big Dan Shear Zone.
See also
- Volcanism of Eastern CanadaVolcanism of Eastern CanadaVolcanism of Eastern Canada has led to the formation of hundreds of volcanic areas and extensive lava formations, indicating volcanism played a major role in shaping its surface. The region's different volcano and lava types originate from different tectonic settings and types of volcanic...
- List of volcanoes of Canada
- List of greenstone belts