Mineralogy of Vera Rubin Ridge From the Mars Science Laboratory CheMin Instrument

E. B. Rampe, T. F. Bristow, R. V. Morris, S. M. Morrison, C. N. Achilles, D. W. Ming, D. T. Vaniman, D. F. Blake, V. M. Tu, S. J. Chipera, A. S. Yen, T. S. Peretyazhko, R. T. Downs, R. M. Hazen, A. H. Treiman, J. P. Grotzinger, N. Castle, P. I. Craig, D. J. Des Marais, M. T. ThorpeR. C. Walroth, G. W. Downs, A. A. Fraeman, K. L. Siebach, R. Gellert, B. Lafuente, A. C. McAdam, P. Y. Meslin, B. Sutter, M. R. Salvatore

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

Vera Rubin ridge (VRR) is an erosion-resistant feature on the northwestern slope of Mount Sharp in Gale crater, Mars, and orbital visible/shortwave infrared measurements indicate it contains red hematite. The Mars Science Laboratory Curiosity rover performed an extensive campaign on VRR to study its mineralogy, geochemistry, and sedimentology to determine the depositional and diagenetic history of the ridge and constrain the processes by which the hematite could have formed. X-ray diffraction (XRD) data from the CheMin instrument of four samples drilled on and below VRR demonstrate differences in iron, phyllosilicate, and sulfate mineralogy and hematite grain size. Hematite is common across the ridge, and its detection in a gray outcrop suggest localized regions with coarse-grained hematite, which commonly forms from warm fluids. Broad XRD peaks for hematite in one sample below VRR and the abundance of FeOT in the amorphous component suggest the presence of nanocrystalline hematite and amorphous Fe oxides/oxyhydroxides. Well crystalline akaganeite and jarosite are present in two samples drilled from VRR, indicating at least limited alteration by acid-saline fluids. Collapsed nontronite is present below VRR, but samples from VRR contain phyllosilicate with d(001) = 9.6 Å, possibly from ferripyrophyllite or an acid-altered smectite. The most likely cementing agents creating the ridge are hematite and opaline silica. We hypothesize late diagenesis can explain much of the mineralogical variation on the ridge, where multiple fluid episodes with variable pH, salinity, and temperature altered the rocks, causing the precipitation and crystallization of phases that are not otherwise in equilibrium.

Original languageEnglish (US)
Article numbere2019JE006306
JournalJournal of Geophysical Research: Planets
Volume125
Issue number9
DOIs
StatePublished - Sep 1 2020

Keywords

  • CheMin
  • Gale crater
  • Mars
  • X-ray diffraction
  • aqueous alteration

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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