Nilokeras Scopulus

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False color oblique view of Nilokeras Scopulus looking north. The cratered plateau at top is Tempe Terra. The dark greenish, smooth area at bottom is floodplain of Kasei Valles. The light blue area at bottom left is a portion of the (younger) central channel of N. Kasei Vallis. Image is Mars Orbital Laser Altimeter (MOLA) colorized elevation overlying Thermal Emission Imaging System (THEMIS) Infrared (IR) daytime mosaic from Mars Odyssey spacecraft. Yellow and light green represent high elevations; dark green and blue are lower elevations. Image is approximately 175 km across. Vertical exaggeration is 3X. Nilokeras Scopulus.jpg
False color oblique view of Nilokeras Scopulus looking north. The cratered plateau at top is Tempe Terra. The dark greenish, smooth area at bottom is floodplain of Kasei Valles. The light blue area at bottom left is a portion of the (younger) central channel of N. Kasei Vallis. Image is Mars Orbital Laser Altimeter (MOLA) colorized elevation overlying Thermal Emission Imaging System (THEMIS) Infrared (IR) daytime mosaic from Mars Odyssey spacecraft. Yellow and light green represent high elevations; dark green and blue are lower elevations. Image is approximately 175 km across. Vertical exaggeration is 3X.
Nilokeras Scopulus based on THEMIS day-time image Nilokeras Scopulus based on day THEMIS.png
Nilokeras Scopulus based on THEMIS day-time image

Nilokeras Scopulus is a long escarpment (cliff) in the northern hemisphere of the planet Mars. It is located along the southeastern boundary of the Tempe Terra plateau and forms the northern valley wall (wallrock boundary) of the downstream portion of the immense Kasei Valles outflow channel system. The escarpment is 765 km long[ citation needed ] [1] and ranges from 1 to a little over 2 km (3300–6600 ft) in height. [2]

Contents

For most of its length, Nilokeras Scopulus lies between lat. 31° and 32° N. It trends west-east, extending from approximately long. 297° to 309° E. [1] The escarpment curves northward at the eastern edge of Tempe Terra where the northern segment of Kasei Valles debouches into Chryse and southwestern Acidalia Planitiae.

Name origin

Nilokeras, which is Greek for "horn of the Nile," was the name given by astronomer E. M. Antoniadi in 1930 to a telescopic albedo feature and canal centered at lat. 30° N., long. 55° W. (See List of Martian canals.) Scopulus is a descriptor term used in planetary geology for an irregular escarpment or cliff. The International Astronomical Union (IAU) formally adopted the name Nilokeras Scopulus in 1976. [1] Scopulus is the Latin term for "crag" or cliff.

Geology

In geomorphology, an escarpment (usually shortened to scarp) is any steep, abrupt slope or cliff along the margin of a plateau, terrace, or other topographic bench. A scarp may be formed by tectonic, erosional, or depositional processes. [3] The term carries no implication of geologic origin.

Nilokeras Scopulus likely formed from a combination of faulting and erosion from flood waters that formed Kasei Valles. Recent geologic mapping of the Kasei Valles region [4] [5] indicates that the west-to-east flow of the Kasei Valles floods followed the existing structural trend of rift valleys in southern Tempe Terra. Thus, the proto-Nilokeras Scopulus was probably an east-west oriented fault scarp or fracture zone (or zone of weakness [6] ) that was eroded and further downcut by at least one (and possibly two) episodes of early catastrophic flooding from the northern Tharsis region. (See outflow channels.) These floods occurred in Hesperian time between about 3.6 and 3.4 billion years ago (Gya).

After initial flooding, the northern Kasei valley was covered by extensive late Hesperian-aged basaltic lava flows from Tharsis. Two final episode of flooding from the Echus Chasma region to the south occurred in Kasei Valles during Amazonian times (<1.8 Gya). The later floods carved the channels south of Nilokeras Scopulus and may not have strongly influenced development of the scarp.

During the course of its history, Nilokeras Scopulus has been subjected to glacial/periglacial processes and modified by groundwater sapping, slumping, collapse, and other mass wasting processes. Rocks making up the scarp face are Noachian or Early Hesperian in age (>3.6 Gya). They probably consist of ancient impact breccias and volcanic materials. Layered bedrock is visible at the top of the escarpment in some medium and high resolution spacecraft images, but the scarp face is largely covered by talus aprons and dust.

See also

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Tharsis Volcanic highland on Mars

Tharsis is a vast volcanic plateau centered near the equator in the western hemisphere of Mars. 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 the Tharsis Montes. The tallest volcano on the planet, Olympus Mons, is often associated with the Tharsis region but is actually located off the western edge of the plateau. The name Tharsis is the Greco-Latin transliteration of the biblical Tarshish, the land at the western extremity of the known world.

Vallis or valles is the Latin word for valley. It is used in planetary geology to name landform features on other planets.

Chryse Planitia Planitia on Mars

Chryse Planitia is a smooth circular plain in the northern equatorial region of Mars close to the Tharsis region to the west, centered at 28.4°N 319.7°E. Chryse Planitia lies partially in the Lunae Palus quadrangle, partially in the Oxia Palus quadrangle, partially in the Mare Acidalium quadrangle. It is 1600 km or 994 mi in diameter and with a floor 2.5 km below the average planetary surface altitude, and has been suggested to be an ancient buried impact basin, thought this is contested. It has several features in common with lunar maria, such as wrinkle ridges. The density of impact craters in the 100 to 2,000 metres range is close to half the average for lunar maria.

Ganges Chasma Chasma on Mars

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Tempe Terra Terra on Mars

Tempe Terra is a heavily cratered highland region in the northern hemisphere of the planet Mars. Located at the northeastern edge of the Tharsis volcanic province, Tempe Terra is notable for its high degree of crustal fracturing and deformation. The region also contains many small shield volcanoes, lava flows, and other volcanic structures.

Echus Chasma

Echus Chasma is a chasma in the Lunae Planum high plateau north of the Valles Marineris canyon system of Mars. It is in the Coprates quadrangle. Clay has been found within it, meaning that water once sat there for a time. It may have been one of the many lakes that have been advanced for the Martian past.

Tharsis Tholus Martian volcano

Tharsis Tholus is an intermediate-sized shield volcano located in the eastern Tharsis region of the planet Mars. The volcano was discovered by the Mariner 9 spacecraft in 1972 and originally given the informal name Volcano 7. In 1973, the International Astronomical Union (IAU) officially designated it Tharsis Tholus. In planetary geology, tholus is the term for a small domical mountain, usually a volcano.

Lunae Palus quadrangle Quadrangle map of Mars

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Coprates quadrangle Map of Mars

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Maja Valles

The Maja Valles are a large system of ancient outflow channels in the Lunae Palus quadrangle on Mars. Their location is 12.6° north latitude and 58.3° west longitude. The name is a Nepali word for "Mars". The Maja Valles begin at Juventae Chasma. Parts of the system have been partially buried by thin volcanic debris. The channels end at Chryse Planitia.

Kasei Valles Valles on Mars

The Kasei Valles are a giant system of canyons in Mare Acidalium and Lunae Palus quadrangles on Mars, centered at 24.6° north latitude and 65.0° west longitude. They are 1,580 km (980 mi) long and were named for the word for "Mars" in Japanese. This is one of the largest outflow channel systems on Mars.

Outflow channels Long, wide swathes of scoured ground on Mars

Outflow channels are extremely long, wide swathes of scoured ground on Mars. They extend many hundreds of kilometers in length and are typically greater than one kilometer in width. They are thought to have been carved by huge outburst floods.

Coprates Chasma

Coprates Chasma is a huge canyon in the Coprates quadrangle of Mars, located at 13.4° south latitude and 61.4° west longitude, part of the Valles Marineris canyon system. It is 966 km (600 mi) long and was named after a classical albedo feature name. It was named from the classical Greek name for the Dez River in Persia.

Enipeus Vallis

Enipeus Vallis is a valley in the northern hemisphere of the planet Mars. It is centered at lat. 37°N, long. 267°E in the Arcadia quadrangle (MC-3) between the large volcano Alba Mons and the Tempe Terra plateau. The valley follows a gently sinuous, north-south path for a distance of about 357 km (222 mi). It is likely an ancient watercourse that formed during the early Hesperian period, around 3.7 billion years ago.

Hesperian Era of Mars geologic history

The Hesperian is a geologic system and time period on the planet Mars characterized by widespread volcanic activity and catastrophic flooding that carved immense outflow channels across the surface. The Hesperian is an intermediate and transitional period of Martian history. During the Hesperian, Mars changed from the wetter and perhaps warmer world of the Noachian to the dry, cold, and dusty planet seen today. The absolute age of the Hesperian Period is uncertain. The beginning of the period followed the end of the Late Heavy Bombardment and probably corresponds to the start of the lunar Late Imbrian period, around 3700 million years ago (Mya). The end of the Hesperian Period is much more uncertain and could range anywhere from 3200 to 2000 Mya, with 3000 Mya being frequently cited. The Hesperian Period is roughly coincident with the Earth's early Archean Eon.

Geological history of Mars Physical evolution of the planet Mars

The geological history of Mars follows the physical evolution of Mars as substantiated by observations, indirect and direct measurements, and various inference techniques. Methods dating back to 17th century techniques developed by Nicholas Steno, including the so-called law of superposition and stratigraphy, used to estimate the geological histories of Earth and the Moon, are being actively applied to the data available from several Martian observational and measurement resources. These include the landers, orbiting platforms, Earth-based observations, and Martian meteorites.

Amazonian (Mars) Time period on Mars

The Amazonian is a geologic system and time period on the planet Mars characterized by low rates of meteorite and asteroid impacts and by cold, hyperarid conditions broadly similar to those on Mars today. The transition from the preceding Hesperian period is somewhat poorly defined. The Amazonian is thought to have begun around 3 billion years ago, although error bars on this date are extremely large. The period is sometimes subdivided into the Early, Middle, and Late Amazonian. The Amazonian continues to the present day.

Galilaei (Martian crater) Crater on Mars

Galilaei is a large impact crater on Mars in the region known as Margaritifer Terra. The crater is in the southern part of the Oxia Palus quadrangle (MC-11) at 5.7°N 333.0°E. Galilaei is located north of Hydaspis Chaos in the area east of Tiu Valles and west of Ares Vallis. The crater was named after the Italian astronomer and physicist Galileo Galilei. Galilaei is one of the numerous large craters that formed during the Noachian Period, which ended around 3.7 billion years ago. The crater floor was modified by superficial geologic processes through Late Hesperian time, as mapped by Tanaka, K.L. and others.

The Thaumasia Plateau is a vast sloping volcanic plain in the western hemisphere of Mars, and is the most extensive component of the Tharsis Rise by area. Syria Planum, Solis Planum, Sinai Planum, and Thaumasia Planum are the constituent sectors of the plateau, which sits between 8 km and 4 km above the surrounding southern highlands. It is bounded by vestigial basement terrains that predate the formation of Tharsis. This area has been proposed to be a drainage basin that sourced the floodwaters forming the outflow channels surrounding Chryse Planitia.

References

  1. 1 2 3 USGS Gazetter of Planetary Nomenclature. http://planetarynames.wr.usgs.gov/Feature/4277.
  2. Mars Orbital Laser Altimeter (MOLA) gridded dataset from JMars. (cf. Christensen, P. et al. (2007). New Insights about Mars from the Creation and Analysis of Mars Global Datasets. American Geophysical Union, abstract #P11E-01. http://adsabs.harvard.edu/abs/2007AGUFM.P11E..01C.)
  3. Bloom, A.L. (1978) Geomorphology: A Systematic Analysis of Late Cenozoic Landforms; Prentice-Hall: Englewood Cliffs, NJ, p. 28.
  4. Chapman, M.G.; et al. (2010a). "Noachian–Hesperian Geologic History of the Echus Chasma and Kasei Valles System on Mars: New Data and Interpretations" (PDF). Earth Planet. Sci. Lett. 294 (3–4): 256–271. Bibcode:2010E&PSL.294..256C. doi:10.1016/j.epsl.2009.11.032.
  5. Chapman, M.G.; et al. (2010b). "Amazonian Geologic History of the Echus Chasma and Kasei Valles System on Mars: New Data and Interpretations". Earth Planet. Sci. Lett. 294 (3–4): 238–255. Bibcode:2010E&PSL.294..238C. doi:10.1016/j.epsl.2009.11.034.
  6. Jöns, H-P. (1995). A Fossil Linear Zone of Weakness Beneath the Kasei Valles, Mars? 26th Lunar and Planetary Science Conference, Abstract #1351. http://www.lpi.usra.edu/meetings/lpsc1995/pdf/1351.pdf.