Ceraunius Fossae
Encyclopedia
Ceraunius Fossae is an area of intensely fractured terrain in the northern Tharsis
region of Mars
. It lies directly south of the large volcano
Alba Mons and consists of ancient highland crust that has been deformed by numerous parallel fault
s and tension cracks. In places, younger lava
flows cover the fractured terrain, dividing it into several large patches or islands.
The faults are mainly narrow, north-south oriented graben
. Graben (the name is both singular and plural) are long, narrow troughs bound by two inward-facing normal faults that enclose a downfaulted block of crust. The graben in Ceraunius Fossae are commonly several kilometers wide, between 100 to slightly over 1000 m deep, and very closely spaced, giving the terrain a rugged ridge and groove topography
. Many of the graben are hundreds of kilometers long and have walls with complex scalloped segments. Some contain pit crater chains
(catenae) at their bottoms, suggesting the presence of deep-seated tension cracks into which surface material has drained.
at lat. 19.78°N, long. 267°E. It was named by Greek Astronomer E. M. Antoniadi in 1930 for the Ceraunian Mountains
on the coast of Epirus
, Greece
(now southwestern Albania
). Fossa
(pl. fossae) is Latin
for ditch and is a descriptor term used in planetary geology
for a long, narrow depression or trench. The International Astronomical Union
(IAU) formally adopted the term Ceraunius Fossae in 1973. The name Ceraunius Fossae is plural and translates into “the Ceraunian trenches,” but the name is commonly used in the singular when referring to the area itself.
. A portion extends northward into the southwestern part of the Arcadia quadrangle
where the fossae diverge around the flanks of Alba Mons to form the Alba and Tantalus Fossae
systems. The area stretches from lat. 18.9° to 38°N and from long. 247° to 255°E. The entire feature has a north-south length of 1137 km.
Ceraunius Fossae lies on a broad topographic ridge up to 1.5 km high, called the Ceraunius rise. The ridge projects from the southern edge of Alba Mons and extends southward for a distance of over 1000 km. The southern half of the Alba Mons volcano is built over the northern extension of this ridge.
. The fractures form when the stresses exceed the yield strength of rock, resulting in deformation of surface materials. Typically, this deformation is manifested as slip on faults that are recognizable in images from orbit. Most of the tectonic features in the western hemisphere of Mars are explained by crustal deformation from the Tharsis bulge (a huge volcanic mass up to 7 km high that covers nearly a quarter of the planet’s surface). Among the processes proposed to explain the tectonic features associated with Tharsis are domal uplifting, magmatic
intrusion
, and volcanic loading (deformation due to the large, sagging weight of the volcanic mass).
The Ceraunius Fossae fractures are extensional
features produced when the crust is stretched apart. The fractures are oriented north-south, radial to an early center of volcano-tectonic activity in Syria Planum
, a region in southern Tharsis. A large number of extensional structures, including graben
and rift
s, radiate outward from the center of Tharsis. Mechanical
studies indicate that a regional pattern of radiating graben and rifts is consistent with stresses caused by loading of the lithosphere by the enormous weight of the Tharsis bulge. The immense Valles Marineris
is probably the best known example of a rift system that lies radial to Tharsis. Several generations of grabens with slightly different orientations are present in Ceraunius Fossae, indicating that stress field
s have changed somewhat over time.
In addition to producing normal faults and graben, extensional stresses can produce dilitant fractures or tension cracks that can open up subsurface voids. When surface material slides into the void, a pit crater may form. Pit craters are distinguishable from impact craters in lacking raised rims and surrounding ejecta blanket
s. On Mars, individual pit craters can coalesce to form crater chain
s (catenae) or troughs with scalloped edges.
Evidence also exists that some of the graben and crater chains in Ceraunius Fossae may be caused by the intrusion of magma
, which forms large underground dikes
. The migration of the magma exploits or opens up fractures in the subsurface, causing a crack or pit crater chain to form at the surface.
Knowledge of the locations and formation mechanisms of pit craters and fossae is important for the future colonization of Mars because subsurface fractures may act as conduits or reservoirs for water and ice.
Tharsis
The Tharsis region on Mars is a vast volcanic plateau centered near the equator in Mars’ western hemisphere. The region is home to the largest volcanoes in the Solar System, including the three enormous shield volcanoes Arsia Mons, Pavonis Mons, and Ascraeus Mons, which are collectively known as...
region of Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...
. It lies directly south of the large volcano
Volcano
2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...
Alba Mons and consists of ancient highland crust that has been deformed by numerous parallel fault
Fault
Fault may refer to:*Fault , planar rock fractures which show evidence of relative movement*Fault , in dog breeding, is an undesirable aspect of structure or appearance that indicates the dog should not be bred...
s and tension cracks. In places, younger lava
Lava
Lava refers both to molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. This molten rock is formed in the interior of some planets, including Earth, and some of their satellites. When first erupted from a volcanic vent, lava is a liquid at...
flows cover the fractured terrain, dividing it into several large patches or islands.
The faults are mainly narrow, north-south oriented graben
Graben
In geology, a graben is a depressed block of land bordered by parallel faults. Graben is German for ditch. Graben is used for both the singular and plural....
. Graben (the name is both singular and plural) are long, narrow troughs bound by two inward-facing normal faults that enclose a downfaulted block of crust. The graben in Ceraunius Fossae are commonly several kilometers wide, between 100 to slightly over 1000 m deep, and very closely spaced, giving the terrain a rugged ridge and groove topography
Topography
Topography is the study of Earth's surface shape and features or those ofplanets, moons, and asteroids...
. Many of the graben are hundreds of kilometers long and have walls with complex scalloped segments. Some contain pit crater chains
Crater chain
A crater chain is a line of craters along the surface of an astronomical body. The descriptor term for crater chains is catena , as specified by the International Astronomical Union's rules on planetary nomenclature....
(catenae) at their bottoms, suggesting the presence of deep-seated tension cracks into which surface material has drained.
Name Origin
The term Ceraunius is from an albedo featureClassical albedo features on Mars
The classical albedo features of Mars are the light and dark features that can be seen on the planet Mars through an Earth-based telescope. Before the age of space probes, several astronomers created maps of Mars on which they gave names to the features they could see. The most popular system of...
at lat. 19.78°N, long. 267°E. It was named by Greek Astronomer E. M. Antoniadi in 1930 for the Ceraunian Mountains
Ceraunian Mountains
The Ceraunian Mountains is a coastal mountain range in southwestern Albania. The name is derived from Ancient Greek Κεραύνια ὄρη, meaning "thunder-split peaks"....
on the coast of Epirus
Epirus (periphery)
Epirus , formally the Epirus Region , is a geographical and administrative region in northwestern Greece. It borders the regions of West Macedonia and Thessaly to the east, West Greece to the south, the Ionian Sea and the Ionian Islands to the west and the country of Albania to the north. The...
, Greece
Greece
Greece , officially the Hellenic Republic , and historically Hellas or the Republic of Greece in English, is a country in southeastern Europe....
(now southwestern Albania
Albania
Albania , officially known as the Republic of Albania , is a country in Southeastern Europe, in the Balkans region. It is bordered by Montenegro to the northwest, Kosovo to the northeast, the Republic of Macedonia to the east and Greece to the south and southeast. It has a coast on the Adriatic Sea...
). Fossa
Fossa
Fossa may refer to:*Fossa dei Leoni, an Italian football supporters association of Milan*La Fossa, an Italian rap group*Formaggio di fossa, a sheep's milk cheese from Sogliano al Rubicone, Italy*Cacio di Fossa, a hard, sharp sheep's milk Italian cheese...
(pl. fossae) is Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
for ditch and is a descriptor term used in planetary geology
Planetary geology
Planetary geology, alternatively known as astrogeology or exogeology, is a planetary science discipline concerned with the geology of the celestial bodies such as the planets and their moons, asteroids, comets, and meteorites...
for a long, narrow depression or trench. The International Astronomical Union
International Astronomical Union
The International Astronomical Union IAU is a collection of professional astronomers, at the Ph.D. level and beyond, active in professional research and education in astronomy...
(IAU) formally adopted the term Ceraunius Fossae in 1973. The name Ceraunius Fossae is plural and translates into “the Ceraunian trenches,” but the name is commonly used in the singular when referring to the area itself.
Location and size
Most of the Ceraunius Fossae are located in the northern Tharsis quadrangleTharsis quadrangle
The Tharsis quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey Astrogeology Research Program. The Tharsis quadrangle is also referred to as MC-9 ....
. A portion extends northward into the southwestern part of the Arcadia quadrangle
Arcadia quadrangle
The Arcadia quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey Astrogeology Research Program. The quadrangle is located in the north-central portion of Mars’ western hemisphere and covers 240° to 300° east longitude and 30° to 65° north latitude...
where the fossae diverge around the flanks of Alba Mons to form the Alba and Tantalus Fossae
Tantalus Fossae
Tantalus Fossae is a group of troughs in the Arcadia quadrangle of Mars, located at 50.9° north latitude and 97.5° west longitude. They are about 2,400 km long and was named after an albedo feature at 35N, 110W. Troughs, like this one are called Fossae on Mars...
systems. The area stretches from lat. 18.9° to 38°N and from long. 247° to 255°E. The entire feature has a north-south length of 1137 km.
Ceraunius Fossae lies on a broad topographic ridge up to 1.5 km high, called the Ceraunius rise. The ridge projects from the southern edge of Alba Mons and extends southward for a distance of over 1000 km. The southern half of the Alba Mons volcano is built over the northern extension of this ridge.
Geology
The Ceraunius Fossae are tectonic features indicating stresses in the planet's 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 :...
. The fractures form when the stresses exceed the yield strength of rock, resulting in deformation of surface materials. Typically, this deformation is manifested as slip on faults that are recognizable in images from orbit. Most of the tectonic features in the western hemisphere of Mars are explained by crustal deformation from the Tharsis bulge (a huge volcanic mass up to 7 km high that covers nearly a quarter of the planet’s surface). Among the processes proposed to explain the tectonic features associated with Tharsis are domal uplifting, magmatic
Magma
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...
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...
, and volcanic loading (deformation due to the large, sagging weight of the volcanic mass).
The Ceraunius Fossae fractures are extensional
Extensional tectonics
Extensional tectonics is concerned with the structures formed, and the tectonic processes associated with, the stretching of the crust or lithosphere.-Deformation styles:...
features produced when the crust is stretched apart. The fractures are oriented north-south, radial to an early center of volcano-tectonic activity in Syria Planum
Syria Planum
Syria Planum is a broad plateau on surface of Mars, forming part of Tharsis region. It is located at the summit of the Tharsis bulge, and was the center of volcanic and tectonic activity in Martian history from the Noachian to the late Hesperian. It has been confirmed that low shield volcanoes...
, a region in southern Tharsis. A large number of extensional structures, including graben
Graben
In geology, a graben is a depressed block of land bordered by parallel faults. Graben is German for ditch. Graben is used for both the singular and plural....
and 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....
s, radiate outward from the center of Tharsis. Mechanical
Mechanics
Mechanics is the branch of physics concerned with the behavior of physical bodies when subjected to forces or displacements, and the subsequent effects of the bodies on their environment....
studies indicate that a regional pattern of radiating graben and rifts is consistent with stresses caused by loading of the lithosphere by the enormous weight of the Tharsis bulge. The immense Valles Marineris
Valles Marineris
Valles Marineris is a system of canyons that runs along the Martian surface east of the Tharsis region...
is probably the best known example of a rift system that lies radial to Tharsis. Several generations of grabens with slightly different orientations are present in Ceraunius Fossae, indicating that stress field
Stress field
A stress field is a region in a body for which the stress is defined at every point. Stress fields are widely used in fluid dynamics and materials science....
s have changed somewhat over time.
In addition to producing normal faults and graben, extensional stresses can produce dilitant fractures or tension cracks that can open up subsurface voids. When surface material slides into the void, a pit crater may form. Pit craters are distinguishable from impact craters in lacking raised rims and surrounding ejecta blanket
Ejecta blanket
An ejecta blanket is a generally symmetrical apron of ejecta that surrounds crater; it is layered thickly at the crater’s rim and thin to discontinuous at the blanket’s outer edge....
s. On Mars, individual pit craters can coalesce to form crater chain
Crater chain
A crater chain is a line of craters along the surface of an astronomical body. The descriptor term for crater chains is catena , as specified by the International Astronomical Union's rules on planetary nomenclature....
s (catenae) or troughs with scalloped edges.
Evidence also exists that some of the graben and crater chains in Ceraunius Fossae may be caused by the intrusion of magma
Magma
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...
, which forms large underground 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...
. The migration of the magma exploits or opens up fractures in the subsurface, causing a crack or pit crater chain to form at the surface.
Knowledge of the locations and formation mechanisms of pit craters and fossae is important for the future colonization of Mars because subsurface fractures may act as conduits or reservoirs for water and ice.