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Appears in Collections:Biological and Environmental Sciences Journal Articles
Peer Review Status: Refereed
Title: In situ and experimental evidence for acidic weathering of rocks and soils on Mars
Author(s): Hurowitz, Joel A
McLennan, Scott M
Tosca, Nicholas J
Arvidson, Raymond E
Michalski, Joseph R
Ming, Douglas Wayne
Schröder, Christian
Squyres, Steven W
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Keywords: experimental
Issue Date: 6-Jan-2006
Date Deposited: 25-Oct-2013
Citation: Hurowitz JA, McLennan SM, Tosca NJ, Arvidson RE, Michalski JR, Ming DW, Schröder C & Squyres SW (2006) In situ and experimental evidence for acidic weathering of rocks and soils on Mars. Journal of Geophysical Research: Planets, 111 (E2), Art. No.: E02S19.
Abstract: Experimental data for alteration of synthetic Martian basalts at pH = 0–1 indicate that chemical fractionations at low pH are vastly different from those observed during terrestrial weathering. Rock surface analyses from Gusev crater are well described by the relationships apparent from low-pH experimental alteration data. A model for rock surface alteration is developed, which indicates that a leached alteration zone is present on rock surfaces at Gusev. This zone is not chemically fractionated to a large degree from the underlying rock interior, indicating that the rock surface alteration process has occurred at low water to rock ratio. The geochemistry of natural rock surfaces analyzed by APXS is consistent with a mixture between adhering soil/dust and the leached alteration zone. The chemistry of rock surfaces analyzed after brushing with the RAT is largely representative of the leached alteration zone. The chemistry of rock surfaces analyzed after grinding with the RAT is largely representative of the interior of the rock, relatively unaffected by the alteration process occurring at the rock surface. Elemental measurements from the Spirit, Opportunity, Pathfinder, and Viking 1 landing sites indicate that soil chemistry from widely separated locations is consistent with the low-pH, low water to rock ratio alteration relationships developed for Gusev rocks. Soils are affected principally by mobility of Fe and Mg, consistent with alteration of olivine-bearing basalt and subsequent precipitation of Fe- and Mg-bearing secondary minerals as the primary control on soil geochemistry.
DOI Link: 10.1029/2005JE002515
Rights: Copyright 2006 by the American Geophysical Union. AGU allows authors to deposit their journal articles if the version is the final published citable version of record, the AGU copyright statement is clearly visible on the posting, and the posting is made 6 months after official publication by the AGU.

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