{{Short description|Crater on Mars}} {{Infobox feature on celestial object | name = Aram Chaos | image = Aram Chaos.jpg | caption = Aram Chaos is the circular depression in the top left. [[Iani Chaos]] is in the bottom right. | location = [[Margaritifer Terra]], [[Mars]] | coordinates = {{coord|2.6|N|21.5|W|globe:mars_type:landmark|display=inline,title}} |depth={{cvt|3|km}} |diameter={{cvt|280|km}} }}
'''Aram Chaos''', centered at 2.6°N, 21.5°W, is a heavily eroded [[impact crater]] on [[Mars]]. It lies at the eastern end of the large canyon [[Valles Marineris]] and close to [[Ares Vallis]]. Various geological processes have reduced it to a circular area of [[chaotic terrain]]. Aram Chaos takes its name from Aram, one of the [[classical albedo features]] observed by [[Giovanni Schiaparelli]], who named it after the [[Biblical]] land of [[Aram (biblical region)|Aram]]. [[Spectroscopic]] observation from orbit indicates the presence of the mineral [[hematite]], likely a signature of a once aqueous environment.
== Description == Aram Chaos is an impact crater on Mars measuring 280 kilometers (170 mi) in diameter. It lies in the [[Oxia Palus quadrangle|Oxia Palus]] quadrangle in a region called [[Margaritifer Terra]], and its exact coordinates on Mars are {{coord|2.6|N|21.5|W|globe:mars_type:landmark|display=}}. The Thermal Emission Imaging System ([[THEMIS]]) on the [[orbiter]] ''[[Mars Odyssey]]'' found [[gray crystalline hematite]] on the floor of Aram Chaos and [[Compact Reconnaissance Imaging Spectrometer for Mars|CRISM]], the spectroscope on the [[Mars Reconnaissance Orbiter|MRO]], found hydrated sulfates, [[jarosite]], and hematite. The floor of Aram Chaos also contains huge blocks of collapsed, or chaotic, terrain that formed when water or ice was catastrophically removed. Small, shallow outlet channels are also visible in the eastern wall of the impact crater, as well as a small outflow channel connecting Aram Chaos with the [[Ares Vallis|Ares Valles]] outflow channel.
== Geology ==
=== Formation === Aram Chaos, as an [[impact crater]], started its formation with the high velocity impact of an unknown smaller body on the surface of Mars. This formed the large, circular depression that originally made up the crater. This crater was then filled with sediments, likely carried by [[aeolian processes]], that were deposited into Aram Chaos over time. Subsequently, and in tandem with the compilation of these sedimentary layers, and aquifer formed beneath the surface of the crater.
==== Chaotic Terrain and Aqueous Environment ==== Following the deposition of sedimentary layers and the formation of the subsurface aquifer, a catastrophic geologic event occurred which caused the release of the subsurface aquifer and the subsequent catastrophic flooding, creating chaotic terrain within Aram Chaos. The repetition of this process led to layered terrains within Aram Chaos, including layers of the mineral hematite.<ref>{{cite thesis |last1=Glotch |first1=Timothy D. |year=2004 |title=The thermal infrared spectral characteristics of hematite and its origin in Aram Chaos, Mars |id={{ProQuest|305210528}} |oclc=63279533 }}</ref><ref>{{cite conference |last1=Sibille |first1=L. |last2=Mueller |first2=R. P. |last3=Niles |first3=P. B. |last4=Glotch |first4=T. |last5=Archer |first5=P. D. |last6=Bell |first6=M. S. |title=Aram Chaos: A Long Lived Subsurface Aqueous Environment with Strong Water Resource Potential for Human Missions on Mars |conference=First Landing Site/Exploration Zone Workshop for Human Missions to the Surface of Mars |date=October 2015 |pages=1048 |id={{ProQuest|2128176559}} |bibcode=2015LPICo1879.1048S |url=https://ntrs.nasa.gov/citations/20150019643 }}</ref><ref>{{cite journal |last1=Glotch |first1=Timothy D. |title=Geologic and mineralogic mapping of Aram Chaos: Evidence for a water-rich history |journal=Journal of Geophysical Research |date=2005 |volume=110 |issue=E9 |pages=E09006 |article-number=2004JE002389 |doi=10.1029/2004JE002389 |bibcode=2005JGRE..110.9006G |doi-access=free }}</ref> Several minerals in Aram Chaos, including the hematite sulfate minerals and water-altered silicates, suggest that a lake probably once existed within the crater at some point in time.<ref>{{cite conference |last1=Lichtenberg |first1=K. A. |last2=Arvidson |first2=R. E. |last3=Morris |first3=R. V. |last4=Murchie |first4=S. L. |last5=Bishop |first5=J. L. |last6=Glotch |first6=T. D. |last7=Noe Dobrea |first7=E. Z. |last8=Mustard |first8=J. F. |last9=Andrews-Hanna |first9=J. |last10=Roach |first10=L. H. |title=Stratigraphy and Relationship of Hydrated Minerals in the Layered Deposits of Aram Chaos, Mars |conference=40th Lunar and Planetary Science Conference |date=March 2009 |page=2326 |bibcode=2009LPI....40.2326L }}</ref><ref>{{cite journal |last1=Lichtenberg |first1=Kimberly A. |last2=Arvidson |first2=Raymond E. |last3=Morris |first3=Richard V. |last4=Murchie |first4=Scott L. |last5=Bishop |first5=Janice L. |last6=Fernandez Remolar |first6=David |last7=Glotch |first7=Timothy D. |last8=Noe Dobrea |first8=Eldar |last9=Mustard |first9=John F. |last10=Andrews-Hanna |first10=Jeffrey |last11=Roach |first11=Leah H. |title=Stratigraphy of hydrated sulfates in the sedimentary deposits of Aram Chaos, Mars |journal=Journal of Geophysical Research |date=10 June 2010 |volume=115 |pages=E00D17 |article-number=2009JE003353 |doi=10.1029/2009JE003353 |doi-access=free }}</ref> Scientists also suggest that flood channels within Aram Chaos were carved within just weeks or months by catastrophic outflows of groundwater from beneath Aram Chaos and nearby regions.<ref>{{Cite web|title=HiRISE {{!}} Uplifted Blocks of Light-Toned Layered Deposits (ESP_054753_1825)|url=https://www.uahirise.org/ESP_054753_1825|access-date=2021-05-08|website=www.uahirise.org}}</ref> Because forming hematite requires liquid water, which cannot exist without a thick atmosphere, the presence of hematite also suggests that Mars had a much thicker atmosphere at some time in the past. Tilting and erosion of Aram Chaos is also evident in satellite imagery taken of the crater.
==== Possible Volcanic Constructs ==== There is a possible volcanic component to the formation of outflow channels in Aram Chaos. By melting the permafrost or ground ice originally in the crater, geothermal activity may have caused the creation of the visible outflow channels in the impact crater.<ref>{{cite conference |last1=Lanz |first1=J. K. |last2=Jaumann |first2=R. |title=Possible Volcanic Constructs in Aram Chaos Revealed by MOC and Their Impact on Outflow Channel Genesis |conference=32nd Annual Lunar and Planetary Science Conference |date=March 2001 |page=1574 |bibcode=2001LPI....32.1574L }}</ref> High resolution MOC images of the chaotic terrains in Aram Chaos show possible volcanic features within the crater, including hills resembling volcanoes, possible magmatic intrusions within the older rock layers, and possible volcanic ash deposits on the crater floor.
=== Mineralogical Composition === Not including dust and regolith common on the surface of Mars, two distinct sections of identifiable minerals have been determined to exist within Aram Chaos: a mixture of [[hematite]] and/or [[goethite]] and a mixture of [[Iron(III) oxide|ferric oxides]] and [[Sulfate|sulfates]].<ref>{{cite thesis |last1=Liu |first1=Yang |year=2013 |title=Spectral Identification and Analyses of Hydrous Mineral Deposits: Implications for the Aqueous History of Aram Chaos and Melas Chasma, Mars |id={{ProQuest|1426182378}} |oclc=861698923 }}</ref> Specifically, these minerals can be seen as two layers in Aram Chaos, described from top to bottom. The first layer consists mostly of nanophase iron oxides, which is about 250–500 meters thick, while the second layer is made up of a less than 500 m layer of polyhydrated sulfate and hematite.<ref>{{cite conference |last1=Lichtenberg |first1=K. |last2=Arvidson |first2=R. |last3=Bishop |first3=J. |last4=Glotch |first4=T. |last5=Noe Dobrea |first5=E. |last6=Murchie |first6=S. |last7=Mustard |first7=J. |last8=Roach |first8=L. |title=Mg- and Fe-Sulfate Layers in Aram Chaos, Mars |conference=American Geophysical Union, Fall Meeting 2008 |date=December 2008 |pages=P44A–09 |bibcode=2008AGUFM.P44A..09L }}</ref><ref>{{cite journal |last1=Massé |first1=M. |last2=Le Mouélic |first2=S. |last3=Bourgeois |first3=O. |last4=Combe |first4=J.-P. |last5=Le Deit |first5=L. |last6=Sotin |first6=C. |last7=Bibring |first7=J.-P. |last8=Gondet |first8=B. |last9=Langevin |first9=Y. |title=Mineralogical composition, structure, morphology, and geological history of Aram Chaos crater fill on Mars derived from OMEGA Mars Express data |journal=Journal of Geophysical Research |date=9 December 2008 |volume=113 |issue=E12 |pages=E12006 |doi=10.1029/2008JE003131 |bibcode=2008JGRE..11312006M |url=https://hal.archives-ouvertes.fr/hal-00488981/file/2008JE003131.pdf }}</ref>
[[Ferric hydroxysulfate]] (Fe3+SO4OH) has been found in Aram Chaos. It was probably formed from the heating and oxidation of hydrated ferrous sulfates. The heat may have come from the deposition of lava or ash. Another psossibility is that heat came from the ground by way of hydrothermal processes. This iron and sulfur compound was discovered with the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument.<ref>Bishop, J. et al. 2025. Characterization of ferric hydroxysulfate on Mars and implications of the geochemical environment supporting its formation. nature communications. https://doi.org/10.1038/s41467-025-61801-2</ref>
== See also == * [[Chaos terrain]] * [[Geology of Mars]] * [[HiRISE]] * [[HiWish program]] * [[List of areas of chaos terrain on Mars]] * [[Martian chaos terrain]] * [[Outflow channels]] * [[Water on Mars]]
{{commons category|Aram Chaos}}
==References== {{Reflist}}
==External links== * [[HiRISE]] [https://web.archive.org/web/20061130063821/http://hiroc.lpl.arizona.edu/images/TRA/TRA_000834_1835/ image of the area] * [http://www.lpi.usra.edu/meetings/lpsc2003/pdf/2046.pdf The geology of Aram Chaos] * [http://www.esa.int/SPECIALS/Mars_Express/SEMG4O9ATME_0.html Mars Express image of the area]
== More Images== <gallery> File:Erosion in Aram Chaos.JPG|Erosion in Aram Chaos, as seen by THEMIS File:Badlands of Aram Chaos.jpg|Badlands of Aram Chaos File:Aram Chaos F669A03.jpg|Viking 1 Orbiter image File:Eastern Floor of Aram Chaos.jpg|Eastern floor of Aram Chaos File:Aram Chaos (2602867599).jpg|Minerals that form in water have been detected in the cliffs in the Aram Chaos region of Mars, as pictured. File:(PSP 002839 1825) Aram Chaos Sediments.jpg|Sediments in Aram Chaos File:(ESP 017528 1830) Gully Landforms in Aram Chaos.jpg|Gully landforms in Aram Choas File:Aram Chaos, perspective view ESA232259.tiff|Aram Chaos in perspective view File:Aram Chaos in false colour ESA217943.jpg|Aram Chaos in false color File:Aram Chaos, black and white ESA227913.jpg|Aram Chaos in black and white File:Aram Chaos (north to the right) ESA206460.tiff|Aram Chaos in true color File:PIA21195 - Aram Chaos - False Color.jpg|Aram Chaos as seen by HiRISE File:Just a Little Landslide.jpg|Hanging valleys in Aram Chaos, as seen by HiRISE under HiWish program File:Blocks in Aram.JPG|Blocks in Aram Chaos showing possible source of water, as seen by THEMIS File:Quadrângulo de Oxia Palus.JPG|Quadrangle map of Oxia Palus labeled with major features. Aram Chaos is near the bottom of the image. File:USGS-Mars-MC-11-OxiaPalusRegion-mola.png|Topographic map of Oxia Palus region of Mars showing the location of a number of chaos regions, including Aram Chaos.
File:Aram Chaos in the Oxia Palus quadrangle, Mars.jpg|Wide view of Aram Chaos, as seen by HiRISE under the HiWish program. The black strip is where data was not gathered. File:Light toned mound in Aram Chaos.jpg|Aram Chaos with a light toned mound as seen by HiRISE under the HiWish program. The mound probably contains water bearing minerals. File:Close view of light toned material in Aram Chaos.jpg|Light toned mound as seen by HiRISE under the HiWish program. The mound probably contains water bearing minerals. File:Dark sand on top of light toned material in Aram Chaos.jpg|Dark sand on top of light toned material, as seen by HiRISE under the HiWish program.
</gallery>{{Geography of Mars}} {{Portal bar|Solar System}}
[[Category:Chaotic terrains on Mars]] [[Category:Impact craters on Mars|#]] [[Category:Margaritifer Sinus quadrangle]]