Oxia Planum is a 200 km-wide clay-bearing

plain In geography, a plain is a flat expanse of land that generally does not change much in elevation, and is primarily treeless. Plains occur as lowlands along valleys or at the base of mountains, as coastal plains, and as plateaus or uplands ...

located on the planet of

Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...

inside the

Oxia Palus quadrangle The Oxia 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 Oxia Palus quadrangle is also referred to as MC-11 (Mars Chart-11). The quadrangl ...

on the eastern border of

Chryse Planitia Chryse Planitia (Greek, "''Golden Plain''") is a smooth circular plain in the northern equatorial region of Mars close to the Tharsis region to the west, centered at . Chryse Planitia lies partially in the Lunae Palus quadrangle, partially in th ...

. The plain lies between the

Mawrth Vallis Mawrth Vallis () (Mawrth means "Mars" in Welsh) is a valley on Mars, located in the Oxia Palus quadrangle at 22.3°N, 343.5°E with an elevation approximately two kilometers below datum. Situated between the southern highlands and northern lowlan ...

outflow channel Outflow channels are extremely long, wide swathes of scoured ground on Mars. 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. ...

to the north-east and the

Ares Vallis 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 Cha ...

to the south-west. In 2019, the

International Astronomical Union The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreac ...

Working Group for Planetary System Nomenclature officially approved Oxia Planum as a feature on the surface of Mars (near 18.275°N 335.368°E). Oxia Planum was one of eight potential landing sites for the European Space Agency and Roscosmos ExoMars mission. After a five-year-long selection process, it was officially selected to be the landing site for ''Rosalind Franklin'' (rover). It met the rover landing criteria based on its latitude, elevation, surface slopes, and its

Noachian The Noachian is a geologic system and early time period on the planet Mars characterized by high rates of meteorite and asteroid impacts and the possible presence of abundant surface water. The absolute age of the Noachian period is uncertain ...

-aged terrains. It was chosen because of its relatively smooth topography and its abundance of hydrated minerals.

Overview

Oxia Planum contains one of the largest exposures of clay-bearing rocks on Mars. The age of the region was calculated to be from ~3.6 billion years old to ~4 billion years old. The site is iron-magnesium rich

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay par ...

s, indicating that water once played a role here. The site sits in an area of valley systems with the exposed rocks exhibiting different compositions, indicating a variety of deposition and wetting environments. Dark resistant units, named for being dark-toned erosion resistant areas, are spread across the surface of the site. The formation of the dark resistant units is hypothesized to have occurred from either fluvial deposits or by volcanic activity during the Amazonian period. The dark resistant units may have preserved the state of the older stratum beneath it. Clay accumulation underneath the remnants of a fan or delta near the outlet of Coogoon Vallis may offer preservation for

biosignature A biosignature (sometimes called chemical fossil or molecular fossil) is any substance – such as an element, isotope, or molecule – or phenomenon that provides scientific evidence of past or present life. Measurable attribute ...

s against the planet's harsh radiation and oxidation environment.

Aeolian features

The aeolian features observed on Oxia Planum indicate a changing wind regime. The formation of

periodic bedrock ridges Periodic Bedrock Ridges (PBRs) are features of the surface geomorphology of Mars and formerly unknown on Earth, first described in a paper in the Journal of Geological Research - Planets, in March 2012,

(PBRs) is hypothesized to have occurred by exposure from erosion or by wind. The PBRs record the oldest wind period of the region and indicate a north-northeast or south-southeast wind direction. The formation of

transverse aeolian ridges Transverse aeolian ridges (TARs) are visually bright features commonly found in topographic depressions on Mars. These small-scale and relict bedforms were first seen in narrow-angle images from the Mars Orbiter Camera (MOC) and were called “ridg ...

(TARs) occurred by wind. The TARs record a second wind period of the region and indicate a northwest or north-northwest to southeast or south-southeast wind direction. Dust devils and windstreaks from the modern wind period indicate a west-northwest to east-southeast and occasionally a north-northeast to south-southwest wind direction.

References

External links

Google Mars zoomable map – centered on the Oxia area

High resolution images
of the Oxia Planum {{Portal bar, Astronomy, Biology, Solar System Oxia Palus quadrangle Plains on Mars

Overview

Aeolian features

See also

References

External links