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Early diagenesis at and below Vera Rubin ridge, Gale crater, Mars

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journal contribution
posted on 2021-11-29, 11:37 authored by SMR Turner, SP Schwenzer, JC Bridges, EB Rampe, CC Bedford, CN Achilles, AC McAdam, N Mangold, LJ Hicks, J Parnell, AA Fraeman, MH Reed
Data returned by NASA’s Mars Science Laboratory Curiosity rover showed evidence for abundant secondary materials, including Fe-oxides, phyllosilicates, and an amorphous component on and below Vera Rubin ridge in the Murray formation. We used equilibrium thermochemical modeling to test the hypothesis that altered sediments were deposited as detrital igneous grains and subsequently underwent diagenesis. Chemical compositions of the Murray formations’ altered components were calculated using data returned by the chemistry and mineralogy X-ray diffraction instrument and the alpha particle X-ray spectrometer on board Curiosity. Reaction of these alteration compositions with a CO2-poor and oxidizing dilute aqueous solution was modeled at 25–100 °C, with 10–50% Fe3+/Fetot of the host rock. The modeled alteration assemblages included abundant phyllosilicates and Fe-oxides at water-to-rock ratios >100. Modeled alteration abundances were directly comparable to observed abundances of hematite and clay minerals at a water-to-rock ratio of 10,000, for system temperatures of 50–100 °C with fluid pH ranging from 7.9 to 9.3. Modeling results suggest that the hematite–clay mineral assemblage is primarily the result of enhanced groundwater flow compared to the Sheepbed mudstone observed at Yellowknife Bay, and underwent further, localized alteration to produce the mineralogy observed by Curiosity.

Funding

UK Space Agency. Grant Number: ST/S001522/1

History

Alternative title

Meteoritics and Planetary Science, 56 (10), 2021, pp. 1905-1932

Author affiliation

Space Research Centre, School of Physics and Astronomy, University of Leicester

Version

  • AM (Accepted Manuscript)

Published in

Meteoritics and Planetary Science

Volume

56

Issue

10

Pagination

1905-1932

Publisher

Wiley

issn

1086-9379

eissn

1945-5100

Acceptance date

2021-08-31

Copyright date

2021

Available date

2022-09-26

Language

English