Outflow channels

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Kasei Valles, seen in MOLA elevation data. Flow was from bottom left to right. North is up. Image is approx. 1,600 km (990 mi) across. The channel system extends another 1,200 km (750 mi) south of this image to Echus Chasma. Kasei Valles topo.jpg
Kasei Valles, seen in MOLA elevation data. Flow was from bottom left to right. North is up. Image is approx. 1,600 km (990 mi) across. The channel system extends another 1,200 km (750 mi) south of this image to Echus Chasma.

Outflow channels are extremely long, wide swathes of scoured ground on Mars. [1] 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.

Contents

Crater counts indicate that most of the channels were cut since the early Hesperian, [2] though the age of the features is variable between different regions of Mars. Some outflow channels in the Amazonis and Elysium Planitiae regions have yielded ages of only tens of millions of years, extremely young by the standards of Martian topographic features. [3] The largest, Kasei Vallis, is around 3,500 km (2,200 mi) long, greater than 400 km (250 mi) wide and exceeds 2.5 km (1.6 mi) in depth cut into the surrounding plains.

The outflow channels contrast with the Martian channel features known as "valley networks", which much more closely resemble the dendritic planform more typical of terrestrial river drainage basins.

Outflow channels tend to be named after the names for Mars in various ancient world languages, or more rarely for major terrestrial rivers. [4] The term outflow channels was introduced in planetology in 1975. [5]

Formation

On the basis of their geomorphology, locations and sources, the channels are today generally thought to have been carved by outburst floods (huge, rare, episodic floods of liquid water), [6] [7] although some authors have made the case for formation by the action of glaciers, [8] lava, [9] or debris flows. [10] [11] Calculations [12] [13] indicate that the volumes of water required to cut such channels at least equal and most likely exceed by several orders of magnitude the present discharges of the largest terrestrial rivers, and are probably comparable to the largest floods known to have ever occurred on Earth (e.g., those that cut the Channeled Scablands in North America or those released during the re-flooding of the Mediterranean basin at the end of the Messinian Salinity Crisis). [14] [15] Such exceptional flow rates and the implied associated volumes of water released could not be sourced by precipitation but rather demand the release of water from some long-term store, probably a subsurface aquifer sealed by ice and subsequently breached by meteorite impact or igneous activity. [16]

List of outflow channels by region

This is a partial list of named channel structures on Mars claimed as outflow channels in the literature, largely following The Surface of Mars by Carr. The channels tend to cluster in certain regions on the Martian surface, often associated with volcanic provinces, and the list reflects this. Originating structures at the head of the channels, if clear and named, are noted in parentheses and in italics after each entry.

Circum-Chryse region

Chryse Planitia is a roughly circular volcanic plain east of the Tharsis bulge and its associated volcanic systems. This region contains the most prominent and numerous outflow channels on Mars. The channels flow east or north into the plain.

Tharsis region

In this region it is particularly difficult to distinguish outflow channels from lava channels but the following features have been suggested as at least overprinted by outflow channel floods:

Amazonis and Elysium Planitiae

Several channels flow either onto the plains of Amazonis and Elysium from the southern highlands, or originate at graben within the plains. This region contains some of the youngest channels. [17] Some of these channels have rare tributaries, and they do not start at a chaos region. It has been suggested the formation mechanisms for these channels may be more variable than for those around Chryse Planitia, perhaps in some cases involving lake breaches at the surface. [18]

Utopia Planitia

Several outflow channels rise in the region west of the Elysium volcanic province and flow northwestward to the Utopia Planitia. As common in the Amazonis and Elysium Planitiae regions, these channels tend to originate in graben. Some of these channels may be influenced by lahars, as indicated by their surface textures and ridged, lobate deposits at their margins and termini. [19] The valleys of Hephaestus Fossae and Hebrus Valles are of extremely unusual form, and although sometimes claimed as outflow channels, are of enigmatic origin. [20]

Hellas region

Three valleys flow from east of its rim down onto the floor of the Hellas basin.

Argyre region

It has been argued that Uzboi, Ladon, Margaritifer and Ares Valles, although now separated by large craters, once comprised a single outflow channel flowing north into Chryse Planitia. [21] The source of this outflow has been suggested as overflow from the Argyre crater, formerly filled to the brim as a lake by channels (Surius, Dzigai, and Palacopus Valles) draining down from the south pole. If real, the full length of this drainage system would be over 8000 km, the longest known drainage path in the solar system. Under this suggestion, the extant form of the outflow channel Ares Vallis would thus be a remolding of a pre-existing structure.

Polar regions

The large troughs present in each pole, Chasma Boreale and Chasma Australe, have both been argued to have been formed by meltwater release from beneath polar ice, as in a terrestrial jökulhlaup. [22] However, others have argued for an eolian origin, with them induced by katabatic winds blowing down from the poles. [23]

See also

Further reading

Related Research Articles

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

<span class="mw-page-title-main">Thermal Emission Imaging System</span> Camera system

The Thermal Emission Imaging System (THEMIS) is a camera on board the 2001 Mars Odyssey orbiter. It images Mars in the visible and infrared parts of the electromagnetic spectrum in order to determine the thermal properties of the surface and to refine the distribution of minerals on the surface of Mars as determined by the Thermal Emission Spectrometer (TES). Additionally, it helps scientists to understand how the mineralogy of Mars relates to its landforms, and it can be used to search for thermal hotspots in the Martian subsurface.

<span class="mw-page-title-main">Chryse Planitia</span> 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, though 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.

<span class="mw-page-title-main">Ares Vallis</span> Vallis on Mars

Ares Vallis is an outflow channel on Mars, named after the Greek name for Mars: Ares, the god of war; it appears to have been carved by fluids, perhaps water. The valley 'flows' northwest out of the hilly Margaritifer Terra, where the Iani Chaos depression 180 km (110 mi) long and 200 km (120 mi) wide) is connected to the beginning of Ares Vallis by a 100 km (62 mi) wide transition zone centered on 342.5° East and 3° North. It then continues through the ancient Xanthe Terra highlands, and ends in a delta-like region of Chryse Planitia. Ares Vallis was the landing site of NASA's Mars Pathfinder spacecraft, which studied a region of the valley near the border with Chryse in 1997.

<span class="mw-page-title-main">Cerberus (Mars)</span> Crater on Mars

Cerberus is a large "dark spot" located on Mars and named after the mythical dog Cerberus. The arcuate (curved) markings in the upper right are in the Amazonis plains and may be sand drifts. The volcano Elysium Mons, a yellow area north of Cerberus, has several channels radiating from its flanks. The three bright spots, upper left, are volcanoes partially veiled by thin clouds.

<span class="mw-page-title-main">Mangala Valles</span> Geographical feature on Mars

The Mangala Valles are a complex system of criss-crossing channels on Mars, located in the Tharsis region and in the Memnonia quadrangle. They originated in the Hesperian and Amazonian epochs. They are thought to be an outflow channel system, carved by catastrophic floods, and the release of vast quantities of water across the Martian surface. This flooding was probably initiated by tectonic stretching and the formation of a graben, Mangala Fossa, at the channels' head, perhaps breaching a pressurized aquifer trapped beneath a thick "cryosphere" beneath the surface. The Mangala Valles contain several basins; after they filled, the overflow went through a series of spillways. One source of waters for the system was the Memonia Fossae, but water also probably came from a large basin centered at 40 degrees S.

<span class="mw-page-title-main">Amazonis Planitia</span> Planitia on Mars

Amazonis Planitia is one of the smoothest plains on Mars. It is located between the Tharsis and Elysium volcanic provinces, to the west of Olympus Mons, in the Amazonis and Memnonia quadrangles, centered at 24.8°N 196.0°E. The plain's topography exhibits extremely smooth features at several different lengths of scale. A large part of the Medusae Fossae Formation lies in Amazonis Planitia.

<span class="mw-page-title-main">Memnonia quadrangle</span> Map of Mars

The Memnonia quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. The Memnonia quadrangle is also referred to as MC-16.

<span class="mw-page-title-main">Cerberus Fossae</span> Series of semi-parallel fissures on Mars formed by faults

The Cerberus Fossae are a series of semi-parallel fissures on Mars formed by faults which pulled the crust apart in the Cerberus region. They are 1235 km across and centered at 11.28 °N and 166.37 °E. Their northernmost latitude is 16.16 °N and their southernmost latitude 6.23 °N. Their easternmost and westernmost longitudes are 174.72 °E and 154.43 °E, respectively. They can be seen in the Elysium quadrangle.

<span class="mw-page-title-main">Athabasca Valles</span> Outflow channel on Mars

The Athabasca Valles are a late Amazonian-period outflow channel system in the central Elysium Planitia region of Mars, located to the south of the Elysium Rise. They are part of a network of outflow channels in this region that are understood to emanate from large fissures in the Martian surface rather than the chaos terrains that source the circum-Chryse outflow channels. The Athabasca Valles in particular emanate from one of the Cerberus Fossae fissures and flow downstream to the southwest, constrained to the south by a wrinkle ridge for over 100 km, before debouching into the Cerberus Palus volcanic plain. The Athabasca Valles are widely understood to be the youngest outflow channel system on the planet.

<span class="mw-page-title-main">Elysium quadrangle</span> One of 30 quadrangle maps of Mars used by the US Geological Survey

The Elysium quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. The Elysium quadrangle is also referred to as MC-15.

<span class="mw-page-title-main">Lunae Palus quadrangle</span> Quadrangle map of Mars

The Lunae Palus quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. The quadrangle is also referred to as MC-10. Lunae Planum and parts of Xanthe Terra and Chryse Planitia are found in the Lunae Palus quadrangle. The Lunae Palus quadrangle contains many ancient river valleys.

<span class="mw-page-title-main">Mare Tyrrhenum quadrangle</span> Part of the surface of Mars

The Mare Tyrrhenum quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. This quadrangle is also referred to as MC-22. It contains parts of the regions Tyrrhena Terra, Hesperia Planum, and Terra Cimmeria.

<span class="mw-page-title-main">Maja Valles</span>

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.

<span class="mw-page-title-main">Kasei Valles</span> 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.

<span class="mw-page-title-main">Enipeus Vallis</span> Vallis on Mars

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.

<span class="mw-page-title-main">Marte Vallis</span> Vallis on Mars

Marte Vallis is a valley in the Amazonis quadrangle of Mars, located at 15 North and 176.5 West. It is 185 km long and was named for the Spanish word for "Mars". It has been identified as an outflow channel, carved in the geological past by catastrophic release of water from aquifers beneath the Martian surface. The surface material is thought to have been created out of 'a'ā and pāhoehoe lava flows from the Elysium volcanic province in the west.

<span class="mw-page-title-main">Amazonian (Mars)</span> 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.

<span class="mw-page-title-main">Lakes on Mars</span> Overview of the presence of lakes on Mars

In summer 1965, the first close-up images from Mars showed a cratered desert with no signs of water. However, over the decades, as more parts of the planet were imaged with better cameras on more sophisticated satellites, Mars showed evidence of past river valleys, lakes and present ice in glaciers and in the ground. It was discovered that the climate of Mars displays huge changes over geologic time because its axis is not stabilized by a large moon, as Earth's is. Also, some researchers maintain that surface liquid water could have existed for periods of time due to geothermal effects, chemical composition or asteroid impacts. This article describes some of the places that could have held large lakes.

The Uzboi-Landon-Morava (ULM) outflow system is a long series of channels and depressions that may have carried water across a major part of Mars. It starts with channels that drain into the Argyre basin in the Argyre quadrangle. Water ponded in the Argyre basin, then the overflow is believed to have traveled northward through Uzboi Vallis, into Landon basin, through Morava Valles, to the floor of Margaritifer basin. Some of the water may have helped to carve Ares Vallis. Altogether, the total area drained for this watershed may have been about 11 X 106 km2 or about 9% of Mars.

References

  1. ↑ Carr, M.H. (2006), The Surface of Mars. Cambridge Planetary Science Series, Cambridge University Press.
  2. ↑ Hartmann, W.K., and Neukum, G. (2001). "Cratering chronology and the evolution of Mars". In: Chronology and Evolution of Mars, ed. R. Kallenbach et al. Dordrecht: Kluwer, p. 165-94.
  3. ↑ Burr, D.M., McEwan, A.S., and Sakimoto, S.E. (2002). "Recent aqueous floods from the Cerberus Fossae", Mars. Geophys. Res. Lett., 29(1), 10.1029/2001G1013345.
  4. ↑ Carr, M.H. (2006), The Surface of Mars. Cambridge Planetary Science Series, Cambridge University Press.
  5. ↑ http://www.vanderbilt.edu/AnS/physics/astrocourses/AST101/readings/mars_water.html
  6. ↑ Baker, V.R. (1982). The Channels of Mars. Austin: Texas University Press.
  7. ↑ Carr,M.H. (1979). "Formation of Martian flood features by release of water from confined aquifers". J. Geophys. Res., 84, 2995-3007.
  8. ↑ Luchitta, B.K. (2001). "Antarctic ice streams and outflow channels on Mars". Geophys. Res. Lett., 28, 403-6.
  9. ↑ Leverington, D.W. (2004). "Volcanic rilles, streamlined islands, and the origin of outflow channels on Mars", Geophys. Res., 109(E11), doi : 10.1029/2004JE002311.
  10. ↑ Tanaka, K.L. (1999). "Debris flow origin for the Simud/Tiu deposit on Mars". J. Geophys. Res., 104, 8637-52.
  11. ↑ Hoffman, N. (2000). White Mars. Icarus, 146, 326-42.
  12. ↑ Williams, R.M., Phillips, R.J., and Malin, M.C. (2000). "Flow rates and duration within Kasei Vallis, Mars: Implications for the formation of a Martian ocean". Geophys. Res. Lett., 27, 1073-6.
  13. ↑ Robinson, M.S., and Takana, K.L. (1990), "Magnitude of a catastrophic flood event in Kasei Vallis, Mars". Geology, 18, 902-5.
  14. ↑ Baker, V.R. (1982). The Channels of Mars. Austin: Texas University Press.
  15. ↑ Garcia-Castellanos, D., et al., (2009). "Catastrophic flood of the Mediterranean after the Messinian Salinity Crisis". Nature, 462, 778-782.
  16. ↑ Carr,M.H. (1979). "Formation of Martian flood features by release of water from confined aquifers". J. Geophys. Res., 84, 2995-3007.
  17. ↑ Burr, D.M., McEwan, A.S., and Sakimoto, S.E. (2002). "Recent aqueous floods from the Cerberus Fossae, Mars". Geophys. Res. Lett., 29(1), 10.1029/2001G1013345.
  18. ↑ Irwin, R.P., Maxwell, T.A., Craddock, R.A., and Leverington, D.W. (2002). "A large paleolake basin at the head of Ma'adim Vallis, Mars". Science, 296, 2209-12.
  19. ↑ Christiansen, E.H. (1989). "Lahars in the Elysium region of Mars". Geology, 17, 203-6.
  20. ↑ Carr, M.H. (2006), The Surface of Mars. Cambridge Planetary Science Series, Cambridge University Press.
  21. ↑ Parker, T.J., Clifford, S.m., and Banerdt, W.B. (2000). "Argyre Planitia and the Mars global hydrologic cycle". LPSC XXXI, Abstract 2033.
  22. ↑ Clifford, S.M. (1987). "Basal polar melting on Mars". J. Geophys. Res., 92, 9135-52.
  23. ↑ Howard, A.D. (2000). "The role of aeolian processes in forming surface features of the martian polar layered deposits". Icarus, 144, 267-88.
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