Basalt weathering rates on Earth and the duration of liquid water on the plains of Gusev Crater, Mars

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Where Martian rocks have been exposed to liquid water, chemistry versus depth profiles could elucidate both Martian climate history and potential for life. The persistence of primary minerals in weathered profiles constrains the exposure time to liquid water: on Earth, mineral persistence times range from {approx}10 ka (olivine) to {approx}250 ka (glass) to {approx}1Ma (pyroxene) to {approx}5Ma (plagioclase). Such persistence times suggest mineral persistence minima on Mars. However, Martian solutions may have been more acidic than on Earth. Relative mineral weathering rates observed for basalt in Svalbard (Norway) and Costa Rica demonstrate that laboratory pH trends can be used to ... continued below

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Steefel, Carl; Hausrath, E.M.; Navarre-Sitchler, A.K.; Sak, P.B.; Steefel, C. & Brantley, S.L. March 15, 2008.

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Where Martian rocks have been exposed to liquid water, chemistry versus depth profiles could elucidate both Martian climate history and potential for life. The persistence of primary minerals in weathered profiles constrains the exposure time to liquid water: on Earth, mineral persistence times range from {approx}10 ka (olivine) to {approx}250 ka (glass) to {approx}1Ma (pyroxene) to {approx}5Ma (plagioclase). Such persistence times suggest mineral persistence minima on Mars. However, Martian solutions may have been more acidic than on Earth. Relative mineral weathering rates observed for basalt in Svalbard (Norway) and Costa Rica demonstrate that laboratory pH trends can be used to estimate exposure to liquid water both qualitatively (mineral absence or presence) and quantitatively (using reactive transport models). Qualitatively, if the Martian solution pH > {approx}2, glass should persist longer than olivine; therefore, persistence of glass may be a pH-indicator. With evidence for the pH of weathering, the reactive transport code CrunchFlow can quantitatively calculate the minimum duration of exposure to liquid water consistent with a chemical profile. For the profile measured on the surface of Humphrey in Gusev Crater, the minimum exposure time is 22 ka. If correct, this estimate is consistent with short-term, episodic alteration accompanied by ongoing surface erosion. More of these depth profiles should be measured to illuminate the weathering history of Mars.

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  • Journal Name: Geology; Journal Volume: 36; Journal Issue: 1; Related Information: Journal Publication Date: 2008

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  • Report No.: LBNL-829E
  • Grant Number: DE-AC02-05CH11231
  • Office of Scientific & Technical Information Report Number: 936584
  • Archival Resource Key: ark:/67531/metadc895100

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  • March 15, 2008

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  • Sept. 27, 2016, 1:39 a.m.

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  • Sept. 30, 2016, 6:19 p.m.

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Steefel, Carl; Hausrath, E.M.; Navarre-Sitchler, A.K.; Sak, P.B.; Steefel, C. & Brantley, S.L. Basalt weathering rates on Earth and the duration of liquid water on the plains of Gusev Crater, Mars, article, March 15, 2008; Berkeley, California. (digital.library.unt.edu/ark:/67531/metadc895100/: accessed August 23, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.