Surface geology Mars

mars terrestrial planet consists of minerals containing silicon , oxygen, metals, , other elements typically make rock. surface of mars composed of tholeiitic basalt, although parts more silica-rich typical basalt , may similar andesitic rocks on earth or silica glass. regions of low albedo suggest concentrations of plagioclase feldspar, northern low albedo regions displaying higher normal concentrations of sheet silicates , high-silicon glass. parts of southern highlands include detectable amounts of high-calcium pyroxenes. localized concentrations of hematite , olivine have been found. of surface covered finely grained iron(iii) oxide dust.

geologic map of mars (usgs, 2014)

although mars has no evidence of structured global magnetic field, observations show parts of planet s crust have been magnetized, suggesting alternating polarity reversals of dipole field have occurred in past. paleomagnetism of magnetically susceptible minerals similar alternating bands found on earth s ocean floors. 1 theory, published in 1999 , re-examined in october 2005 (with of mars global surveyor), these bands suggest plate tectonic activity on mars 4 billion years ago, before planetary dynamo ceased function , planet s magnetic field faded.

it thought that, during solar system s formation, mars created result of stochastic process of run-away accretion of material protoplanetary disk orbited sun. mars has many distinctive chemical features caused position in solar system. elements comparatively low boiling points, such chlorine, phosphorus, , sulphur, more common on mars earth; these elements pushed outward young sun s energetic solar wind.

after formation of planets, subjected so-called late heavy bombardment . 60% of surface of mars shows record of impacts era, whereas of remaining surface underlain immense impact basins caused events. there evidence of enormous impact basin in northern hemisphere of mars, spanning 10,600 8,500 km (6,600 5,300 mi), or 4 times size of moon s south pole – aitken basin, largest impact basin yet discovered. theory suggests mars struck pluto-sized body 4 billion years ago. event, thought cause of martian hemispheric dichotomy, created smooth borealis basin covers 40% of planet.

artist s impression of how mars may have looked 4 billion years ago

the geological history of mars can split many periods, following 3 primary periods:

noachian period (named after noachis terra): formation of oldest extant surfaces of mars, 4.5 3.5 billion years ago. noachian age surfaces scarred many large impact craters. tharsis bulge, volcanic upland, thought have formed during period, extensive flooding liquid water late in period.
hesperian period (named after hesperia planum): 3.5 between 3.3 , 2.9 billion years ago. hesperian period marked formation of extensive lava plains.
amazonian period (named after amazonis planitia): between 3.3 , 2.9 billion years ago present. amazonian regions have few meteorite impact craters, otherwise quite varied. olympus mons formed during period, lava flows elsewhere on mars.

geological activity still taking place on mars. athabasca valles home sheet-like lava flows created 200 mya. water flows in grabens called cerberus fossae occurred less 20 mya, indicating equally recent volcanic intrusions. on february 19, 2008, images mars reconnaissance orbiter showed evidence of avalanche 700-metre-high (2,300 ft) cliff.