Lobate debris apron

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Lobate debris aprons (LDAs) are geological features on Mars, first seen by the Viking Orbiters, consisting of piles of rock debris below cliffs. [1] [2] These features have a convex topography and a gentle slope from cliffs or escarpments, which suggest flow away from the steep source cliff. In addition, lobate debris aprons can show surface lineations as do rock glaciers on the Earth. [3]

Contents

The Mars Reconnaissance Orbiter's Shallow Radar gave a strong reflection from the top and base of LDAs, meaning that pure water ice made up the bulk of the formation (between the two reflections). [4] This is evidence that the LDAs in Hellas Planitia are glaciers covered with a thin layer of rocks. [5] [6] [7] [8] [9] In addition, radar studies in Deuteronilus Mensae show that all lobate debris aprons examined in that region contain ice. [10]

The experiments of the Phoenix lander and the studies of the Mars Odyssey from orbit show that frozen water exists just under the surface of Mars in the far north and south (high latitudes). Most of the ice was deposited as snow when the climate was different. [11] The discovery of water ice in LDAs demonstrates that water is found at even lower latitudes. Future colonists on Mars will be able to tap into these ice deposits, instead of having to travel to much higher latitudes. Another major advantage of LDAs over other sources of Martian water is that they can easily be detected and mapped from orbit. Lobate debris aprons are shown below from the Phlegra Montes which are at a latitude of 38.2 degrees north. The Phoenix lander set down at about 68 degrees north latitude, so the discovery of water ice in LDAs greatly expands the range of water easily available on Mars. [12] It is far easier to land a spaceship near the equator of Mars, so the closer water is available to the equator, the better it will be for colonists.[ citation needed ]

Lineated floor deposits

The floors of some channels show ridges and grooves that seem to flow around obstacles; these features are called lineated floor deposits or lineated valley fill (LVF). Like lobate debris aprons, they are believed to be ice-rich. Some glaciers on the Earth show such features.

It has been suggested that lineated floor deposits began as LDAs. [13] [14] By tracing the paths of the curved ridges characteristic of LDAs, researchers have come to believe that they straighten out to form the ridges of LVF. [15] [16] [17] [18] Both lineated floor deposits and lobate debris aprons often display a strange surface formation called brain terrain because it looks like the surface of the human brain. [19]

Reull Vallis, pictured below, displays these deposits. [20] Sometimes the lineated floor deposits show a chevron pattern, which is further evidence of movement. The picture below taken with HiRISE of Reull Vallis shows these patterns.

Recent observations

Recent analyses of the Nereidum Montes (~35°- 45°S, ~300° - 330°E), and Phlegra Montes (NNE - SSW, between latitudes 30° - 52°N) mountain ranges of Mars have revealed terrains rich in viscous flow features (VFFs), a cyro-geomorphological group of which lobate debris aprons are a sub-class. In a 2014 study, 11,000 VFFs have been recorded between 40° and 60° in northern and southern latitudes, with a 2020 study identifying approximately 3,348 VFFs in the Nereidum Montes range. [21] [22] These LDAs were more extensive and older VFF features (hundreds of Ma) in the range, with the vast majority located in impact craters and surrounding massifs. [21]

Water-ice to lithic ratios of 9:1 were recorded for LDAs by the Mars Reconnaissance Orbiter (MRO), with Berman’s 2020 study presenting Nereidum Montes as possibly containing more water-ice rich LDAs, than other locations in the mid-latitude band. [21] [23] Studies have estimated that LDAs could reach from tens of meters up to 390 meters (1,280 feet) in thickness, with anywhere from 1 to 10 meters (3.3 to 32.8 feet) of overlying regolith preventing sublimation. [23] [24] [25] Late Amazonian glaciation may have occurred in the mid-latitudes due to water-ice emplacement from higher latitudes. This glaciation may have occurred during high obliquity periods in Mars past. [21] [25] [26] [27] Some of these LDAs are overlain with another class of viscous ice flows that is smaller, and younger (tens of Ma) called glacial-like flows (GLFs). Some 320 of these superposed GLFs (SGLFs) have been found, implying successive glaciation periods. [27]

The datasets utilized in these studies included MRO Context Camera (CTX; ~5–6 m/pixel), High-Resolution Imaging Science Experiment (HiRISE) (~25 cm/pixel) images, MRO Shallow Radar (SHARAD), 128 pixel/degree (~463 m/pixel) Mars Global Surveyor (MGS), Mars Orbiter Laser Altimeter (MOLA), Digital Elevation Modelling (DEM), 100 m/pixel THEMIS Day and Night IR mosaics, and the GIS-based (ESRI ArcGIS Desktop) software. [21] [24] [25] [26] [27] [28] [29]

See also

Related Research Articles

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<span class="mw-page-title-main">Deuteronilus Mensae</span> Mensae on Mars

Deuteronilus Mensae is a region on Mars 937 km across and centered at 43.9°N 337.4°W. It covers 344°–325° West and 40°–48° North. Deuteronilus region lies just to the north of Arabia Terra and is included in the Ismenius Lacus quadrangle. It is along the dichotomy boundary, that is between the old, heavily cratered southern highlands and the low plains of the northern hemisphere. The region contains flat-topped knobby terrain that may have been formed by glaciers at some time in the past. Deuteronilus Mensae is to the immediate west of Protonilus Mensae and Ismeniae Fossae. Glaciers persist in the region in modern times, with at least one glacier estimated to have formed as recently as 100,000 to 10,000 years ago. Recent evidence from the radar on the Mars Reconnaissance Orbiter has shown that parts of Deuteronilus Mensae do indeed contain ice.

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

The Ismenius Lacus 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 located in the northwestern portion of Mars' eastern hemisphere and covers 0° to 60° east longitude and 30° to 65° north latitude. The quadrangle uses a Lambert conformal conic projection at a nominal scale of 1:5,000,000 (1:5M). The Ismenius Lacus quadrangle is also referred to as MC-5. The southern and northern borders of the Ismenius Lacus quadrangle are approximately 3,065 km (1,905 mi) and 1,500 km (930 mi) wide, respectively. The north-to-south distance is about 2,050 km (1,270 mi). The quadrangle covers an approximate area of 4.9 million square km, or a little over 3% of Mars' surface area. The Ismenius Lacus quadrangle contains parts of Acidalia Planitia, Arabia Terra, Vastitas Borealis, and Terra Sabaea.

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

The Casius 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 located in the north-central portion of Mars’ eastern hemisphere and covers 60° to 120° east longitude and 30° to 65° north latitude. The quadrangle uses a Lambert conformal conic projection at a nominal scale of 1:5,000,000 (1:5M). The Casius quadrangle is also referred to as MC-6. Casius quadrangle contains part of Utopia Planitia and a small part of Terra Sabaea. The southern and northern borders of the Casius quadrangle are approximately 3,065 km and 1,500 km wide, respectively. The north to south distance is about 2,050 km. The quadrangle covers an approximate area of 4.9 million square km, or a little over 3% of Mars’ surface area.

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

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

The Arcadia 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 located in the north-central portion of Mars’ western hemisphere and covers 240° to 300° east longitude and 30° to 65° north latitude. The quadrangle uses a Lambert conformal conic projection at a nominal scale of 1:5,000,000 (1:5M). The Arcadia quadrangle is also referred to as MC-3.

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

The Hellas quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. The Hellas quadrangle is also referred to as MC-28 . The Hellas quadrangle covers the area from 240° to 300° west longitude and 30° to 65° south latitude on the planet Mars. Within the Hellas quadrangle lies the classic features Hellas Planitia and Promethei Terra. Many interesting and mysterious features have been discovered in the Hellas quadrangle, including the giant river valleys Dao Vallis, Niger Vallis, Harmakhis, and Reull Vallis—all of which may have contributed water to a lake in the Hellas basin in the distant past. Many places in the Hellas quadrangle show signs of ice in the ground, especially places with glacier-like flow features.

<span class="mw-page-title-main">Phlegra Montes</span> System of eroded massifs and knobbly terrain on Mars

The Phlegra Montes are a system of eroded Hesperian–Noachian-aged massifs and knobby terrain in the mid-latitudes of the northern lowlands of Mars, extending northwards from the Elysium Rise towards Vastitas Borealis for nearly 1,400 km (870 mi). The mountain ranges separate the large plains provinces of Utopia Planitia (west) and Amazonis Planitia (east), and were named in the 1970s after a classical albedo feature. The massif terrains are flanked by numerous parallel wrinkle ridges known as the Phlegra Dorsa.

Fretted terrain is a type of surface feature common to certain areas of Mars and was discovered in Mariner 9 images. It lies between two different types of terrain. The surface of Mars can be divided into two parts: low, young, uncratered plains that cover most of the northern hemisphere, and high-standing, old, heavily cratered areas that cover the southern and a small part of the northern hemisphere. Between these two zones is a region called the Martian dichotomy and parts of it contain fretted terrain. This terrain contains a complicated mix of cliffs, mesas, buttes, and straight-walled and sinuous canyons. It contains smooth, flat lowlands along with steep cliffs. The scarps or cliffs are usually 1 to 2 km high. Channels in the area have wide, flat floors and steep walls. Fretted terrain shows up in northern Arabia, between latitudes 30°N and 50°N and longitudes 270°W and 360°W, and in Aeolis Mensae, between 10 N and 10 S latitude and 240 W and 210 W longitude. Two good examples of fretted terrain are Deuteronilus Mensae and Protonilus Mensae.

A concentric crater fill (CCF) is a landform where the floor of a crater is mostly covered with many parallel ridges. It is common in the mid-latitudes of Mars, and is widely believed to be caused by glacial movement. Areas on Mars called Deuteronilus Mensae and Protonilus Mensae contain many examples of concentric crater fill.

<span class="mw-page-title-main">Ring mold crater</span> Type of crater on Mars

A Ring mold crater is a kind of crater on the planet Mars that looks like the ring molds used in baking. They are believed to be caused by an impact into ice. The ice is covered by a layer of debris. They are found in parts of Mars that have buried ice. Laboratory experiments confirm that impacts into ice result in a "ring mold shape." They are also bigger than other craters in which an asteroid impacted solid rock. Impacts into ice warm the ice and cause it to flow into the ring mold shape. These craters are common in lobate debris aprons and lineated valley fill. Many have been found in Mamers Valles, a channel found along the dichotomy boundary in Deuteronilus Mensae. They may be an easy way for future colonists of Mars to find water ice.

<span class="mw-page-title-main">Lineated valley fill</span> Martian geologic feature

Lineated valley fill (LVF), also called lineated floor deposit, is a feature of the floors of some channels on Mars, exhibiting ridges and grooves that seem to flow around obstacles. Shadow measurements show that at least some of the ridges are several metres high. LVF is believed to be ice-rich. Hundreds of metres of ice probably lie protected in LVF under a thin layer of debris. The debris consists of wind-borne dust, material from alcove walls, and lag material remaining after ice sublimated from a rock-ice mixture. Some glaciers on Earth show similar ridges. High-resolution pictures taken with HiRISE reveal that some of the surfaces of lineated valley fill are covered with strange patterns called closed-cell and open-cell brain terrain. The terrain resembles a human brain. It is believed to be caused by cracks in the surface accumulating dust and other debris, together with ice sublimating from some of the surfaces. The cracks are the result stress from gravity and seasonal heating and cooling. This same type of surface is present on Lobate debris aprons and Concentric crater fill so all three are believed to be related.

<span class="mw-page-title-main">Protonilus Mensae</span> Martian plain

Protonilus Mensae is an area of Mars in the Ismenius Lacus quadrangle. It is centered on the coordinates of 43.86° N and 49.4° E. Its western and eastern longitudes are 37° E and 59.7° E. North and south latitudes are 47.06° N and 39.87° N. Protonilus Mensae is between Deuteronilus Mensae and Nilosyrtis Mensae; all lie along the Martian dichotomy boundary. Its name was adapted by the IAU in 1973.

<span class="mw-page-title-main">Nilosyrtis Mensae</span> Fretted terrain in the Casius quadrangle on Mars

Nilosyrtis Mensae is an area of Mars in the Casius quadrangle. It is centered on the coordinates of 36.87° N and 67.9° E. Its western and eastern longitudes are 51.1° E and 74.4° E. North and south latitudes are 36.87° N and 29.61° N. Nilosyrtis Mensae is just to the east of Protonilus Mensae and both lie along the Martian dichotomy boundary. Its name was adapted by the IAU in 1973. It was named after a classical albedo feature, and it is 705 km (438 mi) across.

<span class="mw-page-title-main">Glaciers on Mars</span> Extraterrestrial bodies of ice

Glaciers, loosely defined as patches of currently or recently flowing ice, are thought to be present across large but restricted areas of the modern Martian surface, and are inferred to have been more widely distributed at times in the past. Lobate convex features on the surface known as viscous flow features and lobate debris aprons, which show the characteristics of non-Newtonian flow, are now almost unanimously regarded as true glaciers.

<span class="mw-page-title-main">Evidence of water on Mars found by Mars Reconnaissance Orbiter</span>

The Mars Reconnaissance Orbiter's HiRISE instrument has taken many images that strongly suggest that Mars has had a rich history of water-related processes. Many features of Mars appear to be created by large amounts of water. That Mars once possessed large amounts of water was confirmed by isotope studies in a study published in March 2015, by a team of scientists showing that the ice caps were highly enriched with deuterium, heavy hydrogen, by seven times as much as the Earth. This means that Mars has lost a volume of water 6.5 times what is stored in today's polar caps. The water for a time would have formed an ocean in the low-lying Mare Boreum. The amount of water could have covered the planet about 140 meters, but was probably in an ocean that in places would be almost 1 mile deep.

The common surface features of Mars include dark slope streaks, dust devil tracks, sand dunes, Medusae Fossae Formation, fretted terrain, layers, gullies, glaciers, scalloped topography, chaos terrain, possible ancient rivers, pedestal craters, brain terrain, and ring mold craters.

<span class="mw-page-title-main">Brain terrain</span> Feature of the Martian surface

Brain terrain, also called knobs-brain coral and brain coral terrain, is a feature of the Martian surface, consisting of complex ridges found on lobate debris aprons, lineated valley fill and concentric crater fill. It is so named because it suggests the ridges on the surface of the human brain. Wide ridges are called closed-cell brain terrain, and the less common narrow ridges are called open-cell brain terrain. It is thought that the wide closed-cell terrain contains a core of ice, and when the ice disappears the center of the wide ridge collapses to produce the narrow ridges of the open-cell brain terrain. Shadow measurements from HiRISE indicate the ridges are 4-5 meters high. Brain terrain has been observed to form from what has been called an "Upper Plains Unit." The process begins with the formation of stress cracks. The upper plains unit fell from the sky as snow and as ice coated dust.

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

Sinton is a crater in the Ismenius Lacus quadrangle on Mars. Sinton crater lies in the northern hemisphere, south of the very large crater Lyot and west of Ismeniae Fossae. It was named after Harvard astronomer William M. Sinton. The name was approved in 2007.

<span class="mw-page-title-main">Upper plains unit</span> Surface features of Mars

The upper plains unit is the remnants of a 50-100 meter thick mantling that has been discovered in the mid-latitudes of the planet Mars. It was first investigated in the Deuteronilus Mensae region, but it occurs in other places as well. The remnants consist of sets of dipping layers in impact craters, in depressions, and along mesas. Sets of dipping layers may be of various sizes and shapes—some look like Aztec pyramids from Central America.

References

  1. ↑ Carr, M (2006). The Surface of Mars. Cambridge University Press. ISBN   978-0-521-87201-0.
  2. ↑ Squyres, S (1978). "Martian fretted terrain: Flow of erosional debrid". Icarus . 34 (3): 600–613. Bibcode:1978Icar...34..600S. doi:10.1016/0019-1035(78)90048-9.
  3. ↑ Kieffer, Hugh H.; Jakosky, Bruce M.; Matthews, Mildred Shapley; Snyder, Conway W. (October 1992). Mars: Maps. ISBN   0-8165-1257-4.
  4. ↑ Plaut, Jeffrey J.; Safaeinili, Ali; Holt, John W.; Phillips, Roger J.; Head, James W.; Seu, Roberto; Putzig, Nathaniel E.; Frigeri, Alessandro (28 January 2009). "Radar evidence for ice in lobate debris aprons in the mid-northern latitudes of Mars: RADAR EVIDENCE FOR MID-LATITUDE MARS ICE" (PDF). Geophysical Research Letters. 36 (2): n/a. Bibcode:2009GeoRL..36.2203P. doi:10.1029/2008GL036379. S2CID   17530607. Archived from the original (PDF) on 23 June 2010. Retrieved 18 November 2022.
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  9. ↑ Holt, J. W.; Safaeinili, A.; Plaut, J. J.; Young, D. A.; Head, J. W.; Phillips, R. J.; Campbell, B. A.; Carter, L. M.; Gim, Y.; Seu, R.; Sharad Team (2008-03-01). "Radar Sounding Evidence for Ice within Lobate Debris Aprons Near Hellas Basin, Mid-Southern Latitudes of Mars". Lunar and Planetary Science Conference (1391): 2441. Bibcode:2008LPI....39.2441H. Archived from the original on Dec 22, 2019.
  10. ↑ Petersen, E., et al. 2018. ALL OUR APRONS ARE ICY: NO EVIDENCE FOR DEBRIS-RICH “LOBATE DEBRIS APRONS” IN DEUTERONILUS MENSAE 49th Lunar and Planetary Science Conference 2018 (LPI Contrib. No. 2083). 2354.
  11. ↑ Madeleine, J. et al. 2007. Exploring the northern mid-latitude glaciation with a general circulation model. In: Seventh International Conference on Mars. Abstract 3096.
  12. ↑ "Phoenix - Explore the Cosmos | the Planetary Society". Archived from the original on 2011-08-22. Retrieved 2011-09-08.
  13. ↑ Souness, Colin; Hubbard, Bryn; Milliken, Ralph E.; Quincey, Duncan (2012-01-01). "An inventory and population-scale analysis of martian glacier-like forms". Icarus. 217 (1): 243–255. Bibcode:2012Icar..217..243S. doi:10.1016/j.icarus.2011.10.020. ISSN   0019-1035. Archived from the original on Jan 26, 2022.
  14. ↑ Souness, Colin J.; Hubbard, Bryn (2013-07-01). "An alternative interpretation of late Amazonian ice flow: Protonilus Mensae, Mars". Icarus. 225 (1): 495–505. Bibcode:2013Icar..225..495S. doi:10.1016/j.icarus.2013.03.030. ISSN   0019-1035.
  15. ↑ Head, J. & D. Marchant (2006). "Modification of the Walls of a Noachian Crater in Northern Arabia Terra (24°E, 39°N) During Northern Mid-Latitude Amazonian Glacial Epochs on Mars: Nature and Evolution of Lobate Debris Aprons and Their Relationships to Lineated Valley Fill and Glacial Systems". Lunar Planet. Sci. 37: Abstract #1126. Bibcode:2006LPI....37.1126H.
  16. ↑ Kress, A., J. Head (2008). "Ring-mold craters in lineated valley fill and lobate debris aprons on Mars: Evidence for subsurface glacial ice". Geophys. Res. Lett. 35 (23): L23206-8. Bibcode:2008GeoRL..3523206K. doi: 10.1029/2008gl035501 .{{cite journal}}: CS1 maint: multiple names: authors list (link)
  17. ↑ Baker, David M. H.; Head, James; Marchant, David; et al. (2010). "Flow patterns of lobate debris aprons and lineated valley fill north of Ismeniae Fossae, Mars: Evidence for extensive mid-latitude glaciation in the Late Amazonian". Icarus. 207 (1): 186–209. Bibcode:2010Icar..207..186B. doi:10.1016/j.icarus.2009.11.017.
  18. ↑ Kress., A. & J. Head (2009). "Ring-mold craters on lineated valley fill, lobate debris aprons, and concentric crater fill on Mars: Implications for near-surface structure, composition, and age". Lunar Planet. Sci. 40: abstract 1379.
  19. ↑ Levy, Joseph S.; Head, James W.; Marchant, David R. (2009). "Concentric crater fill in Utopia Planitia: History and interaction between glacial "brain terrain" and periglacial processes". Icarus. 202 (2): 462–476. Bibcode:2009Icar..202..462L. doi:10.1016/j.icarus.2009.02.018.
  20. ↑ "Reull Vallis (Released 22 October 2002) | Mars Odyssey Mission THEMIS". Archived from the original on 2010-06-17. Retrieved 2010-12-19.
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  22. ↑ Levy, Joseph S.; Fassett, Caleb I.; Head, James W.; Schwartz, Claire; Watters, Jaclyn L. (2014). "Sequestered glacial ice contribution to the global Martian water budget: Geometric constraints on the volume of remnant, midlatitude debris-covered glaciers". Journal of Geophysical Research: Planets . 119 (10): 2188–2196. Bibcode:2014JGRE..119.2188L. doi: 10.1002/2014JE004685 . ISSN   2169-9100.
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  25. 1 2 3 Gupta, Vanshika; Gupta, Sharad Kumar; Kim, Jungrack (January 2020). "Automated Discontinuity Detection and Reconstruction in Subsurface Environment of Mars Using Deep Learning: A Case Study of SHARAD Observation". Applied Sciences . 10 (7): 2279. doi: 10.3390/app10072279 .
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  27. 1 2 3 Hepburn, A. J.; Ng, F. S. L.; Livingstone, S. J.; Holt, T. O.; Hubbard, B. (2020). "Polyphase Mid-Latitude Glaciation on Mars: Chronology of the Formation of Superposed Glacier-Like Forms from Crater-Count Dating". Journal of Geophysical Research: Planets. 125 (2): e2019JE006102. Bibcode:2020JGRE..12506102H. doi: 10.1029/2019JE006102 . ISSN   2169-9100.
  28. ↑ www.arcgis.com https://www.arcgis.com/index.html . Retrieved 2021-03-31.{{cite web}}: Missing or empty |title= (help)
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