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Terra Sirenum is a large region in the southern hemisphere of the planet Mars. It is centered at and covers 3900 km at its broadest extent. It covers latitudes 10 to 70 South and longitudes 110 to 180 W.〔http://www.itouchmap.com/?r=marsfeatures&z=7238〕 Terra Sirenum is an upland area notable for massive cratering including the large Newton Crater. Terra Sirenum is in the Phaethontis quadrangle and the Memnonia quadrangle of Mars. A low area in Terra Sirenum is believed to have once held a lake that eventually drained through Ma'adim Vallis.〔Irwin,R, et al. 2002. Geomorphology of Ma'adim Vallis, Mars and associated paleolake basins. J. Geophys. Res. 109(E12): 〕 Wikimolaargyre.jpg|MOLA map showing boundaries of Terra Sirenum and other regions Wikimolasouthpole.jpg|MOLA map showing boundaries of Terra Sirenum near the south pole and other regions == Chloride Deposits == Evidence of deposits of chloride based minerals in Terra Sirenum was discovered by the 2001 Mars Odyssey orbiter's Thermal Emission Imaging System in March 2008. The deposits are approximately 3.5 to 3.9 billion years old. This suggests that near-surface water was widespread in early Martian history, which has implications for the possible existence of Martian life.〔(【引用サイトリンク】title=NASA Mission Finds New Clues to Guide Search for Life on Mars )〕 Besides finding chlorides, MRO discovered iron/magnesium smectites which are formed from long exposure in water.〔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.〕 Based on chloride deposits and hydrated phyllosilicates, Alfonso Davila and others believe there is an ancient lakebed in Terra Sirenum that had an area of 30,000 km2 and was 200 meters deep. Other evidence that supports this lake are normal and inverted channels like ones found in the Atacama desert.〔Davila, A. et al. 2011. A large sedimentary basin in the Terra Sirenum region of the southern highlands of Mars. Icarus. 212: 579-589.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Terra Sirenum」の詳細全文を読む スポンサード リンク
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