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Preliminary results of an experimental study of the interactions of basalt glass and a water vapor atmosphere: Implications for weathering on MarsModels of weathering processes on the surface of Mars invoke hydrothermal alteration as the primary mechanism responsible for clay formation. Previous experimental studies of basalt glass interactions with water under hydrothermal conditions demonstrate that phyllosilicates and zeolites are the primary alteration minerals. Gas-solid weathering is thought to be less thermodynamically favorable and relatively unimportant, however, the experimental alteration of basalt glass under vapor ion conditions (large SA/V) can result in the formation of clay minerals, zeolites, and hydrated calcium silicates. We have undertaken a study of the reacted layers formed on basalt glasses experimentally altered under vapor hydration conditions to resolve this issue. High SA/V ratios promote reaction product buildup in solution and promote alteration mineral formation. It was previously shown that these reaction conditions promote weathering processes similar to those found in nature for tektite glasses, rhyolitic glasses, and basalt glasses. The hydration of basalt glass is described for 100 percent relative humidity experiments at temperatures of 150, 175, and 200 C for up to 400 days. Preliminary characterization of the alteration layers with analytical electron and scanning microscopy suggest that the reaction mechanism includes precipitation of a smectite clay on the outermost surface of the glass. Between the clay and the unreacted glass is an amorphous gel-like phase (palagonite). Our results provide an experimental basis for proposing that basalt glass interactions with vapor atmospheres can be an important source of clay minerals.
Document ID
19930022759
Acquisition Source
Legacy CDMS
Document Type
Other
Authors
Mazer, J. J.
(Argonne National Lab. IL, United States)
Bates, J. K.
(Argonne National Lab. IL, United States)
Bradley, C. R.
(Argonne National Lab. IL, United States)
Date Acquired
September 6, 2013
Publication Date
September 12, 1992
Publication Information
Publication: Lunar and Planetary Inst., MSATT Workshop on Chemical Weathering on Mars
Subject Category
Lunar And Planetary Exploration
Accession Number
93N31948
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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