Argyre Planitia is a plain located within the impact basin Argyre in the southern highlands of

Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin at ...

. Its name comes from a map produced by

Giovanni Schiaparelli Giovanni Virginio Schiaparelli ( , also , ; 14 March 1835 – 4 July 1910) was an Italian astronomer and science historian. Biography He studied at the University of Turin, graduating in 1854, and later did research at Berlin Observatory, ...

in 1877; it refers to Argyre, a mythical island of

silver Silver is a chemical element with the symbol Ag (from the Latin ', derived from the Proto-Indo-European ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical ...

in Greek mythology. Argyre is centered at and lies between 35° and 61° S and 27° and 62° W in the

Argyre quadrangle The Argyre quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. The Argyre quadrangle is also referred to as MC-26 (Mars Chart-26). It contains Argyre P ...

. The basin is approximately wide and drops below the surrounding plains; it is the second deepest impact basin on Mars after Hellas. The crater Galle, located on the east rim of Argyre at , strongly resembles a

smiley A smiley, sometimes referred to as a smiley face, is a basic ideogram that represents a smiling face. Since the 1950s it has become part of popular culture worldwide, used either as a standalone ideogram, or as a form of communication, such a ...

face. The basin was formed by a giant impact during the

Late Heavy Bombardment The Late Heavy Bombardment (LHB), or lunar cataclysm, is a hypothesized event thought to have occurred approximately 4.1 to 3.8 billion years (Ga) ago, at a time corresponding to the Neohadean and Eoarchean eras on Earth. According to the hypot ...

of the early

Solar System The Solar System Capitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar ...

, approximately 3.9 billion years ago, and may be one of the best preserved ancient impact basins from that period. Argyre is surrounded by rugged

massif In geology, a massif ( or ) is a section of a planet's crust that is demarcated by faults or flexures. In the movement of the crust, a massif tends to retain its internal structure while being displaced as a whole. The term also refers to a ...

s which form concentric and radial patterns around the basin. Several mountain ranges are present, some of these mountain ranges include Charitum and

Nereidum Montes The Nereidum Montes is a mountain range on Mars. It stretches 1,143 km, northeast of Argyre Planitia. It is in the Argyre quadrangle. The mountains are named after a Classical albedo feature. Nereidum Montes has gullies in some areas. ...

.Topography and morphology of the Argyre Basin, Mars
' Hiesinger & Head.

Past water flows

Four large Noachian epoch channels lie radial to the basin. Three of these channels (

Surius Vallis Laurentius Surius (translating to Lorenz Sauer; Lübeck, 1523 – Cologne, 23 May 1578) was a German Carthusian Hagiography, hagiographer and church historian. Biography Laurentius Surius was born in Lübeck in 1523, to a wealthy and respected ...

, Dzígai Vallis, and Pallacopas Vallis) flowed into Argyre from the south and east through the rim mountains. The fourth,

Uzboi Vallis Uzboi Vallis is a valley lying situated within the Margaritifer Sinus quadrangle (MC-19) region on Mars. It is named after the Uzboy dry channel, now in Turkmenistan, which repeatedly served as the main channel of the Amu Darya river. The valley b ...

, appears to have flowed out from the basin's north rim to the Chryse region and may have drained a

lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...

of melting ice within the basin. A smaller outflow channel named Nia Valles is relatively fresh-looking, and probably formed during the early Amazonian after the major fluvial and lacustrine episodes had finished. The original basin floor is buried with friable, partially deflated layered material that may be lake

sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand ...

. No inner rings are visible; however, isolated massifs within the basin may be remnants of an inner ring.

Past habitability

After the formation of the impact basin, heat from the impact event along with geothermal heating may have allowed for liquid water to persist for many millions of years. The lake's volume could have been equal to that of Earth's Mediterranean Sea. The basin would have supported a regional environment favorable for the origin and the persistence of

life Life is a quality that distinguishes matter that has biological processes, such as signaling and self-sustaining processes, from that which does not, and is defined by the capacity for growth, reaction to stimuli, metabolism, energy ...

. This region shows a great deal of evidence of glacial activity with flow features, crevasse-like fractures,

drumlin A drumlin, from the Irish word ''droimnín'' ("littlest ridge"), first recorded in 1833, in the classical sense is an elongated hill in the shape of an inverted spoon or half-buried egg formed by glacial ice acting on underlying unconsolidated ...

esker An esker, eskar, eschar, or os, sometimes called an ''asar'', ''osar'', or ''serpent kame'', is a long, winding ridge of stratified sand and gravel, examples of which occur in glaciated and formerly glaciated regions of Europe and North Ame ...

s, tarns,

arête An arête ( ) is a narrow ridge of rock which separates two valleys. It is typically formed when two glaciers erode parallel U-shaped valleys. Arêtes can also form when two glacial cirques erode headwards towards one another, although frequ ...

s, cirques, horns, U-shaped valleys, and terraces. Because of the shapes of Argyre sinuous ridges, the authors agree with previous publications in which they are eskers. Based on morphometrical and geomorphological analysis of the Argyre eskers and their immediate surroundings, it was suggested that they formed beneath an approximately 2 km thick, stagnant (i.e., stationary) ice sheet around 3.6 billion years ago. This stagnant body of ice might have resembled a Piedmont-style glacier comparable to today's

Malaspina Glacier __NOTOC__ The Malaspina Glacier ( Lingít: ''Sít' Tlein'') in southeastern Alaska is the largest piedmont glacier in the world. Situated at the head of the Alaska Panhandle, it is about wide and long, with an area of some . Name The Lingít n ...

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U ...

Gallery

File:Mars atmosphere 2.jpg, The southern rim of Argyre basin, formed by the

Charitum Montes Charitum Montes is a large group of mountains in the Argyre quadrangle of Mars, located at 58.4° south latitude and 40.29° west longitude. It is 850 km across and was named after a classical albedo feature name. Charitum Montes has gullies ...

. Adjacent are sinuous ridges, theorized to be glacial

s. The crater Galle is seen in the background. Image:Argyre basin topo.jpg, MOLA maps showing the geographic context of Argyre. Wikimolaargyre.jpg, MOLA map showing boundaries for Argyre Planitia and other regions File:Gullies in the southern highlands of Mars.jpg,

Gullies A gully is a landform created by running water, mass movement, or commonly a combination of both eroding sharply into soil or other relatively erodible material, typically on a hillside or in river floodplains or terraces. Gullies resemble lar ...

south of Argyre appear to be unequivocal evidence of water erosion. Image:24808multilevelgullies.jpg, Scene in Argyre quadrangle with gullies, alluvival fans, and hollows, as seen by HiRISE under

HiWish program HiWish is a program created by NASA so that anyone can suggest a place for the HiRISE camera on the Mars Reconnaissance Orbiter to photograph. It was started in January 2010. In the first few months of the program 3000 people signed up to use HiRIS ...

. Enlargements of parts of this image are below. Image:24808multiplefans.jpg, Several levels of alluvial fans, as seen by HiRISE under HiWish program. Locations of these fans are indicated in the previous image. Image:24808smallfan.jpg, Small, well-formed alluvial fan, as seen by HiRISE under HiWish program. Location of this fan is shown in an image displayed above. Image:24808hollows.jpg, Enlargement of above image showing hollows with box showing the size of a football field, as seen by HiRISE under HiWish program. Image:ESP 022685 dunesandgullieslabeled.jpg, Gullies, as seen by HiRISE under HiWish program. Location is Nereidum Montes. Image:Surface features in Argyre.jpg, Surface in Argyre quadrangle as seen by HiRISE, under the HiWish program. This is the image of the surface from a single HiRISE image. The scale bar at the top is 500 meters long. Image:Context image for argyrefeatures.JPG, CTX image showing context for the next image. A group of channels are visible in this image. Image:Close-up of Argyrefeatures.JPG, Close-up of surface in Argyre quadrangle, as seen by HiRISE, under the HiWish program.

Interactive Mars map

Notes

References

External links

Argyre Planitia map at ''Google Mars''

Lakes on Mars - Nathalie Cabrol (SETI Talks) * {{authority control Impact craters on Mars, # Plains on Mars Argyre quadrangle