View source for Melas Chasma

{{short description|Chasma on Mars}}
{{Infobox feature on celestial object
|name        = Melas Chasma
|image       = [[File:Melas Chasma THEMIS mosaic.jpg|300px]]
|caption     = Melas Chasma in mosaic of [[Thermal Emission Imaging System|THEMIS]] infrared images, with parts of [[Ius Chasma|Ius]], [[Candor Chasma|Candor]] and [[Coprates Chasma|Coprates]] chasmata visible at the upper left, top and lower right, respectively. Enormous landslide deposits are visible near the junctions of Melas Chasma with each of the neighboring chasmata. Numerous [[graben]] ("[[Fossa (geology)|fossae]]") and ridges ("[[Dorsum (astrogeology)|dorsa]]") stretch across the plateau outside the canyons' rims.
|coordinates = {{coord|10.4|S|72.7|W|globe:mars_type:landmark|display=inline,title}}
|length      = 547.0 km
}}
'''Melas Chasma''' {{IPAc-en|'|m|iː|l|ə|s|_|'|k|æ|z|m|ə}} is a [[canyon]] on [[Mars]], the widest segment of the [[Valles Marineris]] canyon system,<ref name="PSP_004054_1675">[http://hirise.lpl.arizona.edu/PSP_004054_1675 HiRISE | Eroding Layers in Melas Chasma (PSP_004054_1675)<!-- Bot generated title -->]</ref> located east of [[Ius Chasma]] at 9.8°S, 283.6°E in [[Coprates quadrangle]]. It cuts through layered deposits that are thought to be [[sediment]]s from an old [[lake]] that resulted from runoff of the valley networks to the west.<ref>[http://hirise.lpl.arizona.edu/PSP_002828_1700 HiRISE | MSL Landing Site in Melas Chasma (PSP_002828_1700)<!-- Bot generated title -->]</ref> Other theories include windblown sediment deposits and volcanic ash.<ref name="PSP_004054_1675"/> Support for abundant, past [[Water on Mars|water]] in Melas Chasma is the discovery by [[Mars Reconnaissance Orbiter|MRO]] of hydrated sulfates. In addition, sulfate and iron oxides were found by the same satellite.<ref>Murchie, S. et al.  2009.  "A synthesis of Martian aqueous mineralogy after 1 Mars year of observations from the Mars Reconnaissance Orbiter". ''Journal of Geophysical Research'': 114.</ref> Although not chosen as one of the finalists, it was one of eight potential landing sites for the ''[[Mars 2020]]'' rover, a mission with a focus on astrobiology.

The floor of Melas Chasma is about 70% younger massive material that is thought to be volcanic ash whipped up by the wind into eolian features. It also contains rough floor material from the erosion of the canyon walls. Around the edges of Melas is also much slide material.<ref name="USGS I-2010">Witbeck, Tanaka and Scott, Geologic Map of the Valles Marineris Region, Mars; USGS I-2010; 1991.</ref>

In a recent study of southwestern Melas Chasma using high-resolution image, topographic and spectral datasets eleven fan-shaped landforms were found. These fans add to growing evidence that Melas Chasma once held a lake that had fluctuating levels.<ref name="Williams2014">{{cite journal|last1= Williams|first1= R.M.E.|last2= Weitz|first2= C.M.|title= Reconstructing the aqueous history within the southwestern Melas basin, Mars: Clues from stratigraphic and morphometric analyses of fans|journal= Icarus|volume= 242|year= 2014|pages= 19–37|doi= 10.1016/j.icarus.2014.06.030|bibcode= 2014Icar..242...19W}}</ref><ref>Davis, J., P. Grindrod, R. Williams, S. Gupta, M. Balme.  2015.  STRATIGRAPHIC EVIDENCE OF EPISODIC FLUVIAL ACTIVITY IN THE SOUTH MELAS CHASMA BASIN, VALLES MARINERIS, MARS.  46th Lunar and Planetary Science Conference. 1932.pdf</ref>

Using HiRISE images, CTX images, and DEM's, a team of researchers mapped many channels and inverted channels in Melas Chasma. A [[digital elevation model]] (DEM) is a digital model or 3D representation of a terrain's surface. In addition, they found dendritic networks of channels in the plateaus just above the Chasma.  Channels appeared to have formed at different times, hence there were "wet-dry" phases in the history of Melas Chasma. The whole region may have had liquid water for extended periods in the early [[Hesperian]].<ref>Davis, J., et al.  2017.  FLUVIAL MAPPING AND STRATIGRAPHY OF THE SOUTH-WESTERN MELAS BASIN AND PLATEAU, VALLES MARINERIS, MARS: EPISODIC FLUVIAL PHASES AND IMPLICATIONS FOR CLIMATE.  Lunar and Planetary Science XLVIII (2017).  1991.pdf</ref>

<gallery class="center"  widths="190px" heights="180px" >
Image:Marsplateau odyssey big.gif|Combined infrared and daytime observation of Melas Chasma. The shadowed regions (blue) indicate successive landslides.

Image:Melas Chasma.JPG|Cliff in Melas Chasma, as seen by [[Thermal Emission Imaging System|THEMIS]].  Click on image to see relationship of Melas to other features.

Image:Melas Chasma Layered Deposits.JPG|Two views of Melas Chasma Layered Deposits, as seen by [[HiRISE]].  Left picture lies north of other picture on the right.  Pictures are not the same scale.  Click on image to see details of layers.

Image:Layers in Monument Valley.jpg|Layers in Monument Valley.  These are accepted as being formed, at least in part, by water deposition.  Since Mars contains similar layers, water remains as a major cause of layering on Mars.

</gallery>

==See also==

* [[Chasma]]
* [[Coprates quadrangle]]
* [[Digital elevation model]]
* [[Geology of Mars]]
* [[HiRISE]]
* [[Inverted relief]]
* [[Lakes on Mars]]

==References==
{{reflist}}

==External links==
*{{cite journal
 |last          = Metz
 |first         = Joannah M.
 |author2       = John P. Grotzinger
 |author3       = David Mohrig
 |author3-link  = David Mohrig
 |author4       = Ralph Milliken
 |author5       = Bradford Prather
 |author6       = Carlos Pirmez
 |author7       = Alfred S. McEwen
 |author8       = Catherine M. Weitz
 |name-list-style = amp
 |title         = Sublacustrine depositional fans in southwest Melas Chasma
 |journal       = Journal of Geophysical Research
 |date          = 2009
 |volume        = 114
 |issue         = E10002
 |doi           = 10.1029/2009JE003365
 |bibcode       = 2009JGRE..11410002M
 |doi-access= free
 }} 
* [https://www.youtube.com/watch?v=DGBbke1wJRk]  Lakes on Mars - Nathalie Cabrol (SETI Talks)
*{{APOD |date=17 February 2005|title=Melas, Candor and Ophir: Valleys of Mariner}}

{{Geography of Mars}}
{{Mars 2020}}
{{Portal bar|Solar System}}

[[Category:Valleys and canyons on Mars]]
[[Category:Coprates quadrangle]]
[[Category:Mars 2020]]