The potassic sedimentary rocks in Gale Crater, Mars, as seen by ChemCam Onboard Curiosity

Journal of Geophysical Research
By: , and 

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Abstract

The Mars Science Laboratory rover Curiosity encountered potassium-rich clastic sedimentary rocks at two sites in Gale Crater, the waypoints Cooperstown and Kimberley. These rocks include several distinct meters thick sedimentary outcrops ranging from fine sandstone to conglomerate, interpreted to record an ancient fluvial or fluvio-deltaic depositional system. From ChemCam Laser-Induced Breakdown Spectroscopy (LIBS) chemical analyses, this suite of sedimentary rocks has an overall mean K2O abundance that is more than 5 times higher than that of the average Martian crust. The combined analysis of ChemCam data with stratigraphic and geographic locations reveals that the mean K2O abundance increases upward through the stratigraphic section. Chemical analyses across each unit can be represented as mixtures of several distinct chemical components, i.e., mineral phases, including K-bearing minerals, mafic silicates, Fe-oxides, and Fe-hydroxide/oxyhydroxides. Possible K-bearing minerals include alkali feldspar (including anorthoclase and sanidine) and K-bearing phyllosilicate such as illite. Mixtures of different source rocks, including a potassium-rich rock located on the rim and walls of Gale Crater, are the likely origin of observed chemical variations within each unit. Physical sorting may have also played a role in the enrichment in K in the Kimberley formation. The occurrence of these potassic sedimentary rocks provides additional evidence for the chemical diversity of the crust exposed at Gale Crater.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title The potassic sedimentary rocks in Gale Crater, Mars, as seen by ChemCam Onboard Curiosity
Series title Journal of Geophysical Research
DOI 10.1002/2015JE004987
Volume 121
Issue 5
Year Published 2016
Language English
Publisher American Geophysical Union
Publisher location Washington, D.C.
Contributing office(s) Astrogeology Science Center
Description 21 p.
First page 784
Last page 804
Other Geospatial Gale, crater on Mars near the northwestern part of the Aeolis quadrangle at 5.4°S 137.8°E; 154 km (96 mi) in diameter and about 3.5-3.8 billion years old
Online Only (Y/N) N
Additional Online Files (Y/N) N