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Galdakao Crater is a topographic depression in the Aeolis quadrangle of Mars, located at 13.5° South and 183.5° West. It is 35 km in diameter and was named after Galdakao, a town in Basque Country, northern Spain.〔http://planetarynames.wr.usgs.gov/〕 ==Why are Craters important?== The density of impact craters is used to determine the surface ages of Mars and other solar system bodies.〔http://www.lpi.usra.edu/publications/slidesets/stones/〕 The older the surface, the more craters present. Crater shapes can reveal the presence of ground ice. The area around craters may be rich in minerals. On Mars, heat from the impact melts ice in the ground. Water from the melting ice dissolves minerals, and then deposits them in cracks or faults that were produced with the impact. This process, called hydrothermal alteration, is a major way in which ore deposits are produced. The area around Martian craters may be rich in useful ores for the future colonization of Mars.〔http://www.indiana.edu/~sierra/papers/2003/Patterson.html.〕 Studies on the earth have documented that cracks are produced and that secondary minerals veins are deposited in the cracks.〔Osinski, G, J. Spray, and P. Lee. 2001. Impact-induced hydrothermal activity within the Haughton impact structure, arctic Canada: Generation of a transient, warm, wet oasis. Meteoritics & Planetary Science: 36. 731-745〕〔http://www.ingentaconnect.com/content/arizona/maps/2005/00000040/00000012/art00007〕〔Pirajno, F. 2000. Ore Deposits and Mantle Plumes. Kluwer Academic Publishers. Dordrecht, The Netherlands〕 Images from satellites orbiting Mars have detected cracks near impact craters.〔Head, J. and J. Mustard. 2006. Breccia Dikes and Crater-Related Faults in Impact Craters on Mars: Erosion and Exposure on the Floor of a 75-km Diameter Crater at the Dichotomy Boundary. Special Issue on Role of Volatiles and Atmospheres on Martian Impact Craters Meteoritics & Planetary Science〕 Great amounts of heat are produced during impacts. The area around a large impact may take hundreds of thousands of years to cool.〔name="news.discovery.com"〕〔Segura, T, O. Toon, A. Colaprete, K. Zahnle. 2001. Effects of Large Impacts on Mars: Implications for River Formation. American Astronomical Society, DPS meeting#33, #19.08〕〔Segura, T, O. Toon, A. Colaprete, K. Zahnle. 2002. Environmental Effects of Large Impacts on Mars. Science: 298, 1977-1980.〕 Wikigaldakao.jpg|Galdakao Crater, as seen by CTX camera on Mars Reconnaissance Orbiter. 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「Galdakao (crater)」の詳細全文を読む スポンサード リンク
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