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|Title:||Basalt-trachybasalt samples in Gale Crater, Mars|
|Authors:||Edwards, Peter H.|
Bridges, John C.
Schwenzer, Susanne P.
|Publisher:||Wiley, Meteoritical Society|
|Citation:||Meteoritics and Planetary Science, 2017, 52 (11), pp. 2391-2410 (20)|
|Abstract:||The ChemCam instrument on the Mars Science Laboratory (MSL) rover, Curiosity, observed numerous igneous float rocks and conglomerate clasts, reported previously. A new statistical analysis of single-laser-shot spectra of igneous targets observed by ChemCam shows a strong peak at ~55 wt% SiO2 and 6 wt% total alkalis, with a minor secondary maximum at 47–51 wt% SiO2 and lower alkali content. The centers of these distributions, together with the rock textures, indicate that many of the ChemCam igneous targets are trachybasalts, Mg# = 27 but with a secondary concentration of basaltic material, with a focus of compositions around Mg# = 54. We suggest that all of these igneous rocks resulted from low-pressure, olivine-dominated fractionation of Adirondack (MER) class-type basalt compositions. This magmatism has subalkaline, tholeiitic affinities. The similarity of the basalt endmember to much of the Gale sediment compositions in the first 1000 sols of the MSL mission suggests that this type of Fe-rich, relatively low-Mg#, olivine tholeiite is the dominant constituent of the Gale catchment that is the source material for the fine-grained sediments in Gale. The similarity to many Gusev igneous compositions suggests that it is a major constituent of ancient Martian magmas, and distinct from the shergottite parental melts thought to be associated with Tharsis and the Northern Lowlands. The Gale Crater catchment sampled a mixture of this tholeiitic basalt along with alkaline igneous material, together giving some analogies to terrestrial intraplate magmatic provinces.|
|Rights:||Copyright © the authors, 2017. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-commercial License (https://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted use, distribution, and reproduction in any medium non-commercially, provided the original author and source are credited.|
|Description:||Additional supporting information may be found in the online version of this article: Data S1. Basalt–trachybasalt samples from Gale Crater, Mars. Table S1. Error on each dataset. RMSE for CCAM at the two focal points of data representing accuracy. Table S2. Shergottite compositions. Data S2. Reference list.|
|Appears in Collections:||Published Articles, Dept. of Physics and Astronomy|
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