• journal_title：Geology
• Contributor：E.B. Rampe ; M.D. Kraft ; T.G. Sharp ; D.C. Golden ; D.W. Ming ; P.R. Christensen
• Publisher：Geological Society of America
• Date：2012-11-01
• Format：text/html
• Language：en
• Identifier：10.1130/G33215.1
• journal_abbrev：Geology
• issn：0091-7613
• volume：40
• issue：11
• firstpage：995
• section：Articles

Models of Thermal Emission Spectrometer (TES) data suggest that poorly-crystalline weathering products allophane and aluminosilicate gel occur in several low-albedo regions of Mars. The presence of allophane in TES models indicates that the martian surface experienced low-temperature chemical weathering at low water-to-rock ratios and mildly acidic to neutral pH on regional scales. The allophane and gel may be ancient and preserved by a persistently dry martian climate. Alternatively, evidence for recent ground ice in these regions suggests that pedogenic processes causing the formation of poorly-crystalline aluminosilicates could be late Amazonian in age and may be active today. While previous models have suggested that global-scale acidic weathering has occurred on Mars for the past 3.5 billion years, the presence of allophane indicates that acidic weathering was not occurring in these low-albedo regions and that mildly acidic to neutral weathering has been an important regional-scale weathering process on the martian surface.