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Bagnold Dunes Campaign Phase 2: Visible/Near‐Infrared Reflectance Spectroscopy of Longitudinal Ripple Sands
Author(s) -
Johnson Jeffrey R.,
Bell James F.,
Bender Steve,
Cloutis Edward,
Ehlmann Bethany,
Fraeman Abigail,
Gasnault Olivier,
Maurice Sylvestre,
Pinet Patrick,
Thompson Lucy,
Wellington Danika,
Wiens Roger C.
Publication year - 2018
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2018gl079025
Subject(s) - hematite , geology , impact crater , mineralogy , phase (matter) , infrared spectroscopy , infrared , geochemistry , chemistry , optics , astrobiology , physics , organic chemistry
As part of the Phase 2 Bagnold Dune campaign at Gale Crater, Mars, constraints on the geochemistry, mineralogy, and oxidation state of pristine and disturbed linear sand ripples were made using visible/near‐infrared spectral observations for comparison to Phase 1 spectra of the barchan dunes to the north. Spectra acquired by the ChemCam and Mastcam instruments (400–1,000 nm) at four Phase 2 locations revealed similar overall spectral trends between the two regions, but most Phase 2 sands were redder in the visible wavelengths. The majority of targets exhibited lower red/infrared ratios, higher ~530‐nm band depths, and higher red/blue ratios than Phase 1 samples, suggesting a greater proportion of redder, fine‐grained, ferric sands in Phase 2 samples. This is consistent with the slightly greater proportion of hematite in Phase 2 samples as determined from CheMin analyses of the Ogunquit sands, which may reflect contamination from the surrounding hematite‐bearing Murray formation bedrock.