Chemical variability in mineralized veins observed by ChemCam on the lower slopes of Mount Sharp in Gale crater, Mars

Research areas:
Year:
2018
Authors:
Journal:
ICARUS
Volume:
311
Pages:
69-86
Month:
SEP 1
ISSN:
0019-1035
Abstract:
ChemCam has observed a wide range of diagenetic features along the
Curiosity rover traverse including pervasive Ca-sulfate veins.
Observations by multiple instruments on Curiosity indicate that these
veins are hydrated, formed during diagenetic fluid event(s). In this
study, we delve into the chemical variability in these Ca-sulfate
bearing veins and have identified two subsets in the Murray formation
with enrichments in Fe and Fe + Mg. These chemical trends do not reflect
a sampling mixture with the surrounding host rock but likely indicates
the presence of authigenic phases formed during the emplacement of these
veins. Based on passive reflectance spectral analysis and correlation
with other elements, Fe3+ oxides and/or sulfates are proposed to account
for the Fe-rich observations in the vicinity of the Naukluft Plateau
whereas the Fe + Mg trend is also observed in adjacent dark-toned
features with elevated Mn and P near the Old Soaker outcrop. The
specific localization of these observations in the Gale stratigraphy
implies changing pH and redox conditions in the groundwater at the time
of formation of these veins, from oxidizing and likely more acidic near
the Naukluft Plateau to more reducing conditions in the upper part of
the Murray formation. (C) 2018 Elsevier Inc. All rights reserved.