Geological Society of America

T20 Sedimentary Records in the Solar System

Sunday, 25 September 2016
8:00 AM - 12:00 PM
Mile High Ballroom 2C

DIAGENESIS ALONG FRACTURES IN AN EOLIAN SANDSTONE, GALE CRATER, MARS

Paper number: T20-14
Program: Technical Sessions
Time: 11:30 AM – 11:45 AM

Authors

D.W. Ming Presenting Author
NASA Johnson Space Center, Houston, TX
S.M. Morrison
University of Arizona, Tucson, AZ
D.T. Vaniman
Planetary Science Institute, Tucson, AZ
R. Gellert
University of Guelph, Guelph, ON
B. Sutter
NASA Johnson Space Center, Houston, TX
A.H. Treiman
Lunar and Planetary Institute, Houston, TX
The MSL Science Team
California Institute of Technology, Pasadena, CA
A.S. Yen
California Institute of Technology, Pasadena, CA
E.B. Rampe
Jacobs JETS Contract at NASA Johnson Space Center, Houston, TX
J.P. Grotzinger
California Institute of Technology, Pasadena, CA
D.F. Blake
NASA Ames Research Center, Moffett Field, CA
T.F. Bristow
NASA Ames Research Center, Moffett Field, CA
S.J. Chipera
Oklahoma City, OK
R.T. Downs
University of Arizona, Tucson, AZ
R.V. Morris
NASA Johnson Space Center, Houston, TX

Abstract

The Mars Science Laboratory rover Curiosity has been exploring sedimentary deposits in Gale crater since August 2012. The rover has traversed up section through ~100 m of sedimentary rocks deposited in fluvial, deltaic, lacustrine, and eolian environments (Bradbury group and overlying Mount Sharp group). The Stimson formation lies unconformable over a lacustrine mudstone at the base of the Mount Sharp group and has been interpreted to be a cross-bedded sandstone of lithified eolian dunes. Mineralogy of the unaltered Stimson sandstone consists of plagioclase feldspar, pyroxenes, and magnetite with minor abundances of hematite, and Ca-sulfates (anhydrite, bassanite). Unaltered sandstone has a composition similar to the average Mars crustal composition. Alteration “halos” occur adjacent to fractures in the Stimson. Fluids passing through these fractures have altered the chemistry and mineralogy of the sandstone. Silicon and S enrichments and depletions in Al, Fe, Mg, Na, K, Ni and Mn suggest aqueous alteration in an open hydrologic system. Mineralogy of the altered Stimson is dominated by Ca-sulfates, Si-rich X-ray amorphous materials along with plagioclase feldspar, magnetite, and pyroxenes, but less abundant in the altered compared to the unaltered Stimson sandstone and lower pyroxene/plagioclase feldspar. The mineralogy and geochemistry of the altered sandstone suggest a complicated history with several (many?) episodes of aqueous alteration under a variety of environmental conditions (e.g., acidic, alkaline).

Geological Society of America Abstracts with Programs. Vol. 48, No. 7

doi: 10.1130/abs/2016AM-279126

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