lobate debris apron

Lobate debris aprons (LDAs) are geological features on Mars, first seen by the Viking Orbiters, consisting of piles of rock debris below cliffs.{{Cite book |last=Carr |first=M |title=The Surface of Mars |publisher=Cambridge University Press |year=2006 |isbn=978-0-521-87201-0}}{{Cite journal |last=Squyres |first=S |date=1978 |title=Martian fretted terrain: Flow of erosional debrid |journal=Icarus |volume=34 |issue=3 |pages=600–613|doi=10.1016/0019-1035(78)90048-9 |bibcode=1978Icar...34..600S }} 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.{{Cite book|isbn = 0-8165-1257-4|title = Mars: Maps|last1 = Kieffer|first1 = Hugh H.|last2 = Jakosky|first2 = Bruce M.|last3 = Matthews|first3 = Mildred Shapley|last4 = Snyder|first4 = Conway W.|date = October 1992| publisher=University of Arizona Press }}

File:Wikictxp13clifflda.jpg|alt=Wide view of mesa with CTX showing Cliff face and location of lobate debris apron (LDA) Location is Ismenius Lacus quadrangle.|Wide view of mesa with CTX showing cliff face and location of lobate debris apron (LDA) Location is Ismenius Lacus quadrangle.

File:Wikifretesp 028313 2220cliff.jpg|Enlargement of previous CTX image of mesa This image shows the cliff face and detail in the LDA. Image taken with HiRISE under HiWish program. Location is Ismenius Lacus quadrangle.

File:Wikildaf03 036777 2287.jpg|alt=Lobate debris aprons (LDAs) around a mesa, as seen by CTX. Mesa and LDAs are labeled so one can see their relationship. Radar studies have determined that LDAs contain ice; therefore, these can be important for future colonists of Mars. Location is Ismenius Lacus quadrangle.|Lobate debris aprons (LDAs) around a mesa, as seen by CTX. Mesa and LDAs are labeled, so one can see their relationship. Radar studies have determined that LDAs contain ice; therefore, these can be important for future colonists of Mars. Location is Ismenius Lacus quadrangle.

File:WikiESP 036777 2290lda.jpg|Close-up of lobate debris apron (LDA), as seen by HiRISE under HiWish program

File:Lobate Debris Apron in Phlegra Montes.JPG|alt=Lobate debris apron in Phlegra Montes, as seen by HiRISE. The debris apron is probably mostly ice with a thin covering of rock debris, so it could be a useful source of water. Scale bar is 500 meters long.|Lobate debris apron in Phlegra Montes, as seen by HiRISE. The debris apron is probably mostly ice with a thin covering of rock debris, so it could be a useful source of water. Scale bar is {{Convert|500|m|ft|abbr=off|sp=us}} long.

File:Lobate Debris Apron closeup.jpg|Close-up of surface of a lobate debris apron in Hellas quadrangle. Note the lines that are common in rock glaciers on the Earth.

File:Wide view of Debris Apron.jpg|View of a lobate debris apron along a slope in Arcadia quadrangle.

File:Face of Lobate Debris Apron.jpg|Place where a lobate debris apron begins. Note stripes which indicate movement. Image located in Ismenius Lacus quadrangle.

File:Wideviewlda42n18e.jpg|Wide view of mesa with surrounding lobate debris apron, as seen by CTX. Part of this picture is enlarged in the following HiRISE image. Location is the Ismenius Lacus quadrangle.

File:ESP 046273 2225lda.jpg|Part of lobate debris apron, as seen by HiRISE under HiWish program This lobate debris apron surrounds a mesa. Location is the Ismenius Lacus quadrangle.

File:ESP 057389 2195flow.jpg|Lobate debris apron around mesa, as seen by HiRISE under HiWish program

File:ESP 057389 2195lda.jpg|Close view of lobate debris apron around mesa, as seen by HiRISE under HiWish program Brain terrain is visible.

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).{{cite journal |last1=Plaut |first1=Jeffrey J. |last2=Safaeinili |first2=Ali |last3=Holt |first3=John W. |last4=Phillips |first4=Roger J. |last5=Head |first5=James W. |last6=Seu |first6=Roberto |last7=Putzig |first7=Nathaniel E. |last8=Frigeri |first8=Alessandro |title=Radar evidence for ice in lobate debris aprons in the mid-northern latitudes of Mars: RADAR EVIDENCE FOR MID-LATITUDE MARS ICE |journal=Geophysical Research Letters |date=28 January 2009 |volume=36 |issue=2 |pages=n/a |doi=10.1029/2008GL036379 |bibcode=2009GeoRL..36.2203P |s2cid=17530607 |url=http://www.planetary.brown.edu/pdfs/3733.pdf|archive-url=https://web.archive.org/web/20100623192455/http://www.planetary.brown.edu/pdfs/3733.pdf|archive-date=23 June 2010 |access-date=18 November 2022 |language=en-us}} This is evidence that the LDAs in Hellas Planitia are glaciers covered with a thin layer of rocks.{{Cite journal |last=Head |first=J |date=2005 |title=Tropical to mid-latitude snow and ice accumulation, flow and glaciation on Mars |journal=Nature |volume=434 |issue=7031 |pages=346–350|doi=10.1038/nature03359 |pmid=15772652 |bibcode=2005Natur.434..346H |s2cid=4363630 }}[https://archive.today/20121205041820/http://www.marstoday.com/news/viewpr.html?pid=18050] {{Dead link|date=July 2022}}{{Cite web |date=April 23, 2008 |title=Glaciers Reveal Martian Climate Has Been Recently Active |url=http://news.brown.edu/pressreleases/2008/04/martian-glaciers |archive-url=https://web.archive.org/web/20211221013922/https://news.brown.edu/articles/2008/04/martian-glaciers |archive-date=Dec 21, 2021 |website=News from Brown}}{{Cite journal |last1=Plaut |first1=Jeffrey J. |last2=Safaeinili |first2=Ali |last3=Holt |first3=John W. |last4=Phillips |first4=Roger J. |last5=Head |first5=James W. |last6=Seu |first6=Roberto |last7=Putzig |first7=Nathaniel E. |last8=Frigeri |first8=Alessandro |date=28 January 2009 |title=Radar evidence for ice in lobate debris aprons in the mid-northern latitudes of Mars |journal=Geophysical Research Letters |language=en |volume=36 |issue=2 |pages= |doi=10.1029/2008GL036379|bibcode=2009GeoRL..36.2203P |s2cid=17530607 |doi-access=free }}{{Cite journal |last1=Holt |first1=J. W. |last2=Safaeinili |first2=A. |last3=Plaut |first3=J. J. |last4=Young |first4=D. A. |last5=Head |first5=J. W. |last6=Phillips |first6=R. J. |last7=Campbell |first7=B. A. |last8=Carter |first8=L. M. |last9=Gim |first9=Y. |last10=Seu |first10=R. |last11=Sharad Team |date=2008-03-01 |title=Radar Sounding Evidence for Ice within Lobate Debris Aprons Near Hellas Basin, Mid-Southern Latitudes of Mars |url=https://ui.adsabs.harvard.edu/abs/2008LPI....39.2441H |journal=Lunar and Planetary Science Conference |issue=1391 |pages=2441 |bibcode=2008LPI....39.2441H |archive-url=https://web.archive.org/web/20191222092447/https://ui.adsabs.harvard.edu/abs/2008LPI....39.2441H/abstract |archive-date=Dec 22, 2019}} In addition, radar studies in Deuteronilus Mensae show that all lobate debris aprons examined in that region contain ice.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.

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.Madeleine, J. et al. 2007. Exploring the northern mid-latitude glaciation with a general circulation model. In: Seventh International Conference on Mars. Abstract 3096. 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.{{cite web|url=http://www.planetary.org/explore/topics/phoenix |title=Phoenix - Explore the Cosmos | the Planetary Society |access-date=2011-09-08 |url-status=dead |archive-url=https://web.archive.org/web/20110822221353/http://www.planetary.org/explore/topics/phoenix/ |archive-date=2011-08-22 }} 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|date= October 2020}}

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.{{Cite journal |last1=Souness |first1=Colin |last2=Hubbard |first2=Bryn |last3=Milliken |first3=Ralph E. |last4=Quincey |first4=Duncan |date=2012-01-01 |title=An inventory and population-scale analysis of martian glacier-like forms |url=https://www.sciencedirect.com/science/article/pii/S0019103511004131 |journal=Icarus |language=en |volume=217 |issue=1 |pages=243–255 |doi=10.1016/j.icarus.2011.10.020 |bibcode=2012Icar..217..243S |issn=0019-1035 |archive-url=https://web.archive.org/web/20220126100034/https://www.sciencedirect.com/science/article/abs/pii/S0019103511004131 |archive-date=Jan 26, 2022|url-access=subscription }}{{Cite journal |last1=Souness |first1=Colin J. |last2=Hubbard |first2=Bryn |date=2013-07-01 |title=An alternative interpretation of late Amazonian ice flow: Protonilus Mensae, Mars |url=https://www.sciencedirect.com/science/article/pii/S0019103513001462 |journal=Icarus |language=en |volume=225 |issue=1 |pages=495–505 |doi=10.1016/j.icarus.2013.03.030 |bibcode=2013Icar..225..495S |issn=0019-1035|url-access=subscription }} 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.{{cite journal |author1=Head, J. |author2=D. Marchant |name-list-style=amp |date=2006 |title=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 |url=https://ui.adsabs.harvard.edu/abs/2006LPI....37.1126H/abstract |journal=Lunar Planet. Sci. |volume=37 |page=Abstract #1126|bibcode=2006LPI....37.1126H }}{{cite journal |author=Kress, A., J. Head |date=2008 |title=Ring-mold craters in lineated valley fill and lobate debris aprons on Mars: Evidence for subsurface glacial ice |journal=Geophys. Res. Lett. |volume=35 |issue=23 |page=L23206-8 |bibcode=2008GeoRL..3523206K |doi=10.1029/2008gl035501 |doi-access=free}}{{cite journal |author=Baker |first1=David M. H. |last2=Head |first2=James |last3=Marchant |first3=David |display-authors=etal |date=2010 |title=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 |url=https://www.researchgate.net/publication/222564869 |journal=Icarus |volume=207 |issue=1 |pages=186–209 |bibcode=2010Icar..207..186B |doi=10.1016/j.icarus.2009.11.017}}{{cite journal |author1=Kress., A. |author2=J. Head |name-list-style=amp | date = 2009 | title = Ring-mold craters on lineated valley fill, lobate debris aprons, and concentric crater fill on Mars: Implications for near-surface structure, composition, and age | journal = Lunar Planet. Sci. | volume = 40 | page = abstract 1379}} 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.{{cite journal |author=Levy |first1=Joseph S. |last2=Head |first2=James W. |last3=Marchant |first3=David R. |date=2009 |title=Concentric crater fill in Utopia Planitia: History and interaction between glacial "brain terrain" and periglacial processes |journal=Icarus |volume=202 |issue=2 |pages=462–476 |bibcode=2009Icar..202..462L |doi=10.1016/j.icarus.2009.02.018}}

File:Wikifrettedctxp22.jpg|Wide CTX view showing mesa and buttes with lobate debris aprons and lineated valley fill around them. Location is Ismenius Lacus quadrangle.

File:WikiESP 020769 2225fretted.jpg|alt=Close-up of lineated valley fill (LVF), as seen by HiRISE under HiWish program Note: this is an enlargement of the previous CTX image.|Close-up of lineated valley fill (LVF), as seen by HiRISE under HiWish program. This is an enlargement of the previous CTX image.

File:Wikifrettedctxpo5.jpg|alt=Wide CTX view of mesa showing lineated valley fill and lobate debris apron (LDA). Both are believed to be debris-covered glaciers. Location is Ismenius Lacus quadrangle.|Wide CTX view of mesa showing lineated valley fill and lobate debris apron (LDA). Both are believed to be debris-covered glaciers. Location is Ismenius Lacus quadrangle.

File:Wikifretesp 027639 2210lda.jpg|Close-up of lobate debris apron from the previous CTX image of a mesa. Image shows open-cell brain terrain and closed-cell brain terrain, which is more common. Open-cell brain terrain is thought to hold a core of ice. Image is from HiRISE under HiWish program.

File:25246brainseroding.jpg|Closed-cell brain terrain, as seen by HiRISE under the HiWish program. This type of surface is common on lobate debris aprons, concentric crater fill, and lineated valley fill.

File:Htalk23815 2215lvfclose.jpg|Open and closed-cell brain terrain, as seen by HiRISE, under HiWish program.

Reull Vallis, pictured below, displays these deposits.{{cite web|url=http://themis.asu.edu/zoom-20021022a |title=Reull Vallis (Released 22 October 2002) | Mars Odyssey Mission THEMIS |access-date=2010-12-19 |url-status=dead |archive-url=https://web.archive.org/web/20100617191548/http://themis.asu.edu/zoom-20021022a |archive-date=2010-06-17 }} 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.{{Cite journal|last1=Berman|first1=Daniel C.|last2=Chuang|first2=Frank C.|last3=Smith|first3=Isaac B.|last4=Crown|first4=David A.|date=2021-02-01|title=Ice-rich landforms of the southern mid-latitudes of Mars: A case study in Nereidum Montes|url=https://www.sciencedirect.com/science/article/pii/S0019103520305091|journal=Icarus|language=en|volume=355|pages=114170|doi=10.1016/j.icarus.2020.114170|bibcode=2021Icar..35514170B|s2cid=226335719 |issn=0019-1035|url-access=subscription}}{{Cite journal |last1=Levy |first1=Joseph S. |last2=Fassett |first2=Caleb I. |last3=Head |first3=James W. |last4=Schwartz |first4=Claire |last5=Watters |first5=Jaclyn L. |date=2014 |title=Sequestered glacial ice contribution to the global Martian water budget: Geometric constraints on the volume of remnant, midlatitude debris-covered glaciers |journal=Journal of Geophysical Research: Planets |language=en |volume=119 |issue=10 |pages=2188–2196 |bibcode=2014JGRE..119.2188L |doi=10.1002/2014JE004685 |issn=2169-9100 |doi-access=free}} 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.

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.{{Cite journal |last1=Schmidt |first1=Louise Steffensen |last2=Hvidberg |first2=Christine Schøtt |last3=Kim |first3=Jung Rack |last4=Karlsson |first4=Nanna Bjørnholt |date=December 2019 |title=Non-linear flow modelling of a Martian Lobate Debris Apron |journal=Journal of Glaciology |language=en |volume=65 |issue=254 |pages=889–899 |bibcode=2019JGlac..65..889S |doi=10.1017/jog.2019.54 |issn=0022-1430 |doi-access=free|hdl=20.500.11815/1551 |hdl-access=free }} Studies have estimated that LDAs could reach from tens of meters up to {{Convert|390|m|ft|abbr=off|sp=us}} in thickness, with anywhere from {{Convert|1 to 10|m|ft|abbr=off|sp=us}} of overlying regolith preventing sublimation.{{Cite journal|date=2021-02-01|title=Landforms indicative of regional warm based glaciation, Phlegra Montes, Mars|journal=Icarus|language=en|volume=355|pages=114173|doi=10.1016/j.icarus.2020.114173|issn=0019-1035|doi-access=free|last1=Gallagher|first1=Colman|last2=Butcher|first2=Frances E.G.|last3=Balme|first3=Matt|last4=Smith|first4=Isaac|last5=Arnold|first5=Neil|bibcode=2021Icar..35514173G}}{{Cite journal |last1=Gupta |first1=Vanshika |last2=Gupta |first2=Sharad Kumar |last3=Kim |first3=Jungrack |date=January 2020 |title=Automated Discontinuity Detection and Reconstruction in Subsurface Environment of Mars Using Deep Learning: A Case Study of SHARAD Observation |journal=Applied Sciences |language=en |volume=10 |issue=7 |pages=2279 |doi=10.3390/app10072279 |doi-access=free}} 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.{{Cite journal|last1=Hepburn|first1=A. J.|last2=Ng|first2=F. S. L.|last3=Holt|first3=T. O.|last4=Hubbard|first4=B.|date=2020|title=Late Amazonian Ice Survival in Kasei Valles, Mars|journal=Journal of Geophysical Research: Planets|language=en|volume=125|issue=11|pages=e2020JE006531|doi=10.1029/2020JE006531|bibcode=2020JGRE..12506531H|issn=2169-9100|doi-access=free|hdl=2160/9cf03348-2ac0-4bd7-9711-42c2b210fb85|hdl-access=free}}{{Cite journal|last1=Hepburn|first1=A. J.|last2=Ng|first2=F. S. L.|last3=Livingstone|first3=S. J.|last4=Holt|first4=T. O.|last5=Hubbard|first5=B.|date=2020|title=Polyphase Mid-Latitude Glaciation on Mars: Chronology of the Formation of Superposed Glacier-Like Forms from Crater-Count Dating|journal=Journal of Geophysical Research: Planets|language=en|volume=125|issue=2|pages=e2019JE006102|doi=10.1029/2019JE006102|bibcode=2020JGRE..12506102H|issn=2169-9100|doi-access=free}} 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.

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.{{Cite web|url=https://www.arcgis.com/index.html|access-date=2021-03-31|website=www.arcgis.com}}{{Cite web|title=GIS Mapping Software, Location Intelligence & Spatial Analytics {{!}} Esri|url=https://www.esri.com/en-us/home|access-date=2021-03-31|website=www.esri.com|language=en-us}}

Lobate debris aprons (LDA's) and lineated valley fill (LVF) are now thought to be the same--mostly ice with a covering of debris, their shapes are dependent on their locations. When confined within a valley, LVF is present; in contrast when not confined, this flowing debris covered ice forms LDA's.Wueller, L., et al. 2025. Relationships between lobate debris aprons and lineated valley fill on Mars: Evidence for an extensive Amazonian valley glacial landsystem in Mamers Valles. Icarus. Volume 426, 15 116373

Gallery

Image:Hellas quantangle.JPG|Map of the eastern part of Hellas Planitia (a vast impact crater), showing two large river valleys that slope left, toward the floor of the crater.

File:Reull Vallis lineated deposits.jpg|Reull Vallis with lineated floor deposits, as seen by THEMIS. Click on image to see relationship to other features.

Image:Niger Vallis hirise.JPG|Niger Vallis with features typical of this latitude, as seen by HiRISE. Chevron pattern results from movement of ice-rich material. Click on image to see chevron pattern and mantle.

File:Phlegra Montes in Cebrenia quadrangle.JPG|Material moving down slope in Phlegra Montes, as seen by HiRISE. Movement is probably aided by water/ice.

References

External links

[https://www.youtube.com/watch?v=_sUUKcZaTgA Martian Ice - Jim Secosky - 16th Annual International Mars Society Convention]
[https://www.youtube.com/watch?v=m2ERsEXAq_s Jeffrey Plaut - Subsurface Ice - 21st Annual International Mars Society Convention]

Category:Geology of Mars

Category:Surface features of Mars