P51E-06
Feldspars Detected by ChemCam in Gale Crater with Implications for Future Martian Exploration
Friday, 18 December 2015: 09:15
2009 (Moscone West)
Patrick James Gasda1, Eric Carlson2, Roger C Wiens3, John Bridges4, Violaine Sautter5, Agnes Cousin6, Sylvestre Maurice6, Olivier Gasnault7, Samuel M Clegg1 and ChemCam/MSL Science Team, (1)Los Alamos National Laboratory, Los Alamos, NM, United States, (2)New Mexico Institute of Mining and Technology, Socorro, NM, United States, (3)Space Science and Applications, Los Alamos, NM, United States, (4)University of Leicester, Leicester, United Kingdom, (5)CNRS, Paris Cedex 16, France, (6)IRAP, Toulouse, France, (7)Universite de Toulouse, Toulouse Cedex 4, France
Abstract:
Feldspar is a common igneous mineral that can shed light on parent magma temperatures, pressures, and compositions. During the first 801 sols of the NASA Mars Science Laboratory mission, we have detected 125 possible feldspar grains using the ChemCam LIBS instrument. We analyzed spectra from successive laser shots at the same location and approximate whole rock compositions for each target. Feldspar-containing targets range from tephrite-basanite to trachyandesite. The most common feldspar type is andesine; no targets are >An60. Over 30% are anorthoclase, and ~10% have potassium contents up to Or60. Individual shot measurements in a single spot suggest some feldspars are zoned. Most of these rocks are either float or incorporated into conglomerates, and thus we do not know their provenance. Many of the samples may originate from the Gale crater walls, indicative of Southern Highland ancient crust. Some may also be flung from further away (e.g., emplaced by impact processes). Hence, these rocks may give us a general clue to the variety of evolved igneous materials on Mars. The ubiquity of feldspars at Gale suggests that they have been significantly underestimated for the Southern Highlands, if not for the whole of Mars. For example, significant abundance of andesitic feldspars in both the southern highland and northern lowlands of Mars would imply that Martian volcanism has produced a greater extent of evolved igneous materials to a greater degree than previously thought. Remote sensing instruments are insensitive to plagioclase due to dust cover, lack of exposures, or low feldspar FeO content. However, the Mars 2020 rover will be equipped with 3 new instruments, the arm-mounted SHERLOC Raman, PIXL µXRF, and the mast-mounted SuperCam combined Raman-LIBS instruments, which should help characterize Martian feldspars. Additionally, the SuperCam instrument plans to include three feldspars in its suite of 20+ onboard standards to improve feldspar chemical analysis.
