Terrane
Encyclopedia
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. The crustal block or fragment preserves its own distinctive geologic history, which is different from that of the surrounding areas – hence the term "exotic" terrane. The suture zone
between a terrane and the crust it attaches to is usually identifiable as a fault
.
Older usage of terrane simply described a series of related rock formations or an area having a preponderance of a particular rock or rock groups.
. It is a piece of crust
which has been transported laterally, usually as part of a larger plate, and is relatively buoyant due to thickness or low density. When the plate of which it was a part subducted under another plate, the terrane failed to subduct, detached from its transporting plate, and accreted onto the overriding plate. Therefore, the terrane transferred from one plate to the other. Typically, accreting terranes are portions of continental crust
which have rifted off another continental mass and been transported surrounded by oceanic crust, or old island arc
s formed at some distant subduction zone.
A tectonostratigraphic terrane is a fault-bounded package of rocks of at least regional extent characterized by a geologic history which differs from that of neighboring terranes. The basic characteristics of these terranes is that the present spatial relations are not compatible with the inferred geologic histories. Where juxtaposed terranes processes coeval strata, it must be demonstrable that the geologic evolutions are different and incompatible, and there must be an absence of intermediate lithofacies which could link the strata
The concept of tectonostratigraphic terrane developed from studies in the 1970s of the complicated Pacific Cordillera
n ("backbone") orogenic
margin of North America
, a complex and diverse geological potpourri that was difficult to explain until the new science of plate tectonics illuminated the ability of crustal fragments to "drift" thousands of miles from their origin and fetch up, crumpled, against an exotic shore. Such terranes were dubbed "accreted terranes
" by geologist
s.
When terranes are composed of repeated accretionary events, and hence are composed of subunits with distinct history and structure, they may be called superterranes.
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...
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
Accretion (geology)
Accretion is a process by which material is added to a tectonic plate or a landmass. This material may be sediment, volcanic arcs, seamounts or other igneous features.-Description:...
or "sutured
Suture (geology)
In structural geology, a suture is a major fault zone through an orogen or mountain range. Sutures separate terranes, tectonic units that have different plate tectonic, metamorphic and paleogeographic histories...
" to crust lying on another plate. The crustal block or fragment preserves its own distinctive geologic history, which is different from that of the surrounding areas – hence the term "exotic" terrane. The suture zone
Suture (geology)
In structural geology, a suture is a major fault zone through an orogen or mountain range. Sutures separate terranes, tectonic units that have different plate tectonic, metamorphic and paleogeographic histories...
between a terrane and the crust it attaches to is usually identifiable as a fault
Geologic fault
In geology, a fault is a planar fracture or discontinuity in a volume of rock, across which there has been significant displacement along the fractures as a result of earth movement. Large faults within the Earth's crust result from the action of tectonic forces...
.
Older usage of terrane simply described a series of related rock formations or an area having a preponderance of a particular rock or rock groups.
Overview
A tectonostratigraphic terrane is not necessarily an independent microplate in origin, since it may not contain the full thickness of the lithosphereLithosphere
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 :...
. It is a piece of crust
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...
which has been transported laterally, usually as part of a larger plate, and is relatively buoyant due to thickness or low density. When the plate of which it was a part subducted under another plate, the terrane failed to subduct, detached from its transporting plate, and accreted onto the overriding plate. Therefore, the terrane transferred from one plate to the other. Typically, accreting terranes are portions of continental crust
Continental crust
The continental crust is the layer of igneous, sedimentary, and metamorphic rocks which form the continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called sial due to more felsic, or granitic, bulk composition, which lies in...
which have rifted off another continental mass and been transported surrounded by oceanic crust, or old island arc
Island arc
An island arc is a type of archipelago composed of a chain of volcanoes which alignment is arc-shaped, and which are situated parallel and close to a boundary between two converging tectonic plates....
s formed at some distant subduction zone.
A tectonostratigraphic terrane is a fault-bounded package of rocks of at least regional extent characterized by a geologic history which differs from that of neighboring terranes. The basic characteristics of these terranes is that the present spatial relations are not compatible with the inferred geologic histories. Where juxtaposed terranes processes coeval strata, it must be demonstrable that the geologic evolutions are different and incompatible, and there must be an absence of intermediate lithofacies which could link the strata
The concept of tectonostratigraphic terrane developed from studies in the 1970s of the complicated Pacific Cordillera
Pacific Cordillera
The Pacific Cordillera is a top-level physiographic region of Canada. This cordillera is part of the Western Cordillera of North America. The mountain ranges in this region were covered during the Pleistocene by the Cordilleran Ice Sheet...
n ("backbone") orogenic
Orogeny
Orogeny refers to forces and events leading to a severe structural deformation of the Earth's crust due to the engagement of tectonic plates. Response to such engagement results in the formation of long tracts of highly deformed rock called orogens or orogenic belts...
margin of 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...
, a complex and diverse geological potpourri that was difficult to explain until the new science of plate tectonics illuminated the ability of crustal fragments to "drift" thousands of miles from their origin and fetch up, crumpled, against an exotic shore. Such terranes were dubbed "accreted terranes
Accretion (geology)
Accretion is a process by which material is added to a tectonic plate or a landmass. This material may be sediment, volcanic arcs, seamounts or other igneous features.-Description:...
" by geologist
Geologist
A geologist is a scientist who studies the solid and liquid matter that constitutes the Earth as well as the processes and history that has shaped it. Geologists usually engage in studying geology. Geologists, studying more of an applied science than a theoretical one, must approach Geology using...
s.
When terranes are composed of repeated accretionary events, and hence are composed of subunits with distinct history and structure, they may be called superterranes.
Tibet
- Lhasa Terrane
- Qiangtang Terrane
- Xigaze Terrane
- Bainang Terrane
- Zedong Terrane
- Dazhuqu Terrane
Australasia
- Brook Street Terrane
- Buller Terrane
- Caples Terrane
- East Tasmanian Terrane
- Glenburgh Terrane
- Maitai Terrane
- Murihiku Terrane
- Narryer Gneiss TerraneNarryer Gneiss TerraneThe Narryer Gneiss Terrane is a geological complex in Western Australia that is composed of a tectonically interleaved and polydeformed mixture of granite, mafic intrusions and metasedimentary rocks in excess of 3.3 billion years old, with the majority of the Narryer Gneiss Terrane in excess of 3.6...
- Takaka Terrane
- Torlesse Composite Terrane
- Waipapa Composite Terrane
- West Tasmanian Terrane
Europe
- Armorican terraneArmorican terraneThe Armorican terrane, Armorican terrane assemblage, or simply Armorica, refers to a microcontinent or group of continental fragments that rifted away from Gondwana towards the end of the Silurian and collided with Laurussia towards the end of the Carboniferous during the Variscan orogeny...
- AvaloniaAvaloniaAvalonia 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...
- Avalon Composite Terrane
- Briançonnais Terrane
- Central Highlands Terrane
- Central Southern Uplands Terrane
- Charnwood Terrane
- Hebridean TerraneHebridean TerraneThe Hebridean Terrane is one of the terranes that form part of the Caledonian orogenic belt in northwest Scotland. Its boundary with the neighbouring Northern Highland Terrane is formed by the Moine Thrust Belt...
- Leinster-Lakesman Terrane
- Midland Valley Terrane
- North Armorican Composite Terrane
- Northern Highlands Terrane
- Rosslare-Monian Terranes
- Southern North Sea Terrane
- Tregor-La Hague Terrane
- Wrekin Terrane
North America
- Buffalo Head Terrane
- Cache Creek TerraneCache Creek TerraneThe Cache Creek Terrane is a geologic terrane in British Columbia and southern Yukon, Canada. It consists of volcanics, carbonate rocks, coarse clastic rocks and small amounts of ultramafic rock, chert and argillite....
- Carolina TerraneCarolina terraneThe Carolina terrane is a terrane in northwestern South Carolina, a volcanic island arc in the Southern Alleghenian orogeny....
- Hottah Terrane
- Salinian BlockSalinian BlockThe Salinian Block or Salinian terrane is a geologic terrane which lies west of the main trace of the San Andreas Fault system in California. It is bounded on the south by the Big Pine Fault in Ventura County, and on the west by the Nacimiento Fault...
- Smartville BlockSmartville BlockThe Smartville Block, also called the Smartville Complex or Smartville Intrusive Complex, is a geologic zone in the foothills of the Sierra Nevada mountain range, in the historic Gold Country in eastern California.-Gold:...
- Sonomia TerraneSonomia TerraneThe Sonomia Terrane is a geologic crustal block known as a "terrane" whose remnants today lie in northwest Nevada. The terrane acquired its name from the Sonoma Range in that region. The Sonoma Terrane is associated with the Golconda Thrust, a formation named for its proximity to the town of...
- StikiniaStikiniaStikinia is the name of a tectonostratigraphic terrane in the Canadian Cordillera of British Columbia, Canada. It was formed in a volcanic arc environment during the Paleozoic and Mesozoic periods...
- Wrangellia TerraneWrangellia TerraneThe Wrangellia Terrane is a geologic concept encompassing a large arc of terrain extending from the U.S state of southcentral Alaska through southwestern Yukon and along the Coast of British Columbia in Canada...
- Yakutat BlockYakutat BlockThe Yakutat Block is a terrane in the process of accreting to the North American continent along the south central coast of Alaska. It has been displaced about 600 km northward since the Cenozoic along the Queen Charlotte-Fairweather fault system....
- Yukon-Tanana TerraneYukon-Tanana TerraneThe Yukon-Tanana Terrane is a tectonic terrane that extends from central Alaska through central Yukon and into northern British Columbia, Canada and Southeast Alaska, USA. Extending over 2000 km, the YTT is the largest tectonostratigraphic terrane in the northern North American Cordillera...
South America
- Arequipa-Antofalla
- ChileniaChileniaChilenia was an ancient microcontinent or terrane whose history affected many of the older rocks of central Chile and western Argentina. It was once separated by oceanic crust from the Cuyania terrane to which it accreted at ~420-390 Ma when Cuyania was already amalgamated with Gondwana.-Sources:*...
- Chiloé BlockChiloé BlockThe Chiloé Block or Chiloé Terrane is a geotectonic unit making up the basement of large parts of south-central Chile between 41° and 45°S. Due to its form it is sometimes called Chiloé Sliver. The Chiloé Block is believed to be an ancient microcontinent or terrane that collided with the South...
- CuyaniaCuyaniaThe Precordillera Terrane or Cuyania was an ancient microcontinent or terrane whose history affected many of the older rocks of Cuyo in Argentina. It was separated by oceanic crust from the Chilenia terrane which accreted into it at ~420-390 Ma when Cuyania was already amalgamated with Gondwana...
- PampiaPampiaPampia was an ancient microcontinent or terrane that collided with Rio de la Plata Craton and Río Apas Craton during the Pampean orogeny of late Proterozoic and early Cambrian. It was one of the first terranes to be amalgamated to the old cratons of the east, and was followed by the suturing of...
- Sierra Nevada de Santa MartaSierra Nevada de Santa MartaThe Sierra Nevada de Santa Marta is an isolated mountain range apart from the Andes chain that runs through Colombia. Reaching an altitude of 5,700 metres above sea level just 42 km from the Caribbean coast, the Sierra Nevada is the world's highest coastal range...