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Alkaline volcanic rocks from the Columbia Hills, Gusev crater, Mars

Journal of Geophysical Research E: Planets

By:
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DOI: 10.1029/2006JE002698

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Abstract

Irvine, Backstay, and Wishstone are the type specimens for three classes of fine-grained or fragmental, relatively unaltered rocks with distinctive thermal emission spectra, found as float on the flanks of the Columbia Hills. Chemical analyses indicate that these rocks are mildly alkaline basalt, trachybasalt, and tephrite, respectively. Their mineralogy consists of Na- and K-rich feldspar(s), low- and high-Ca pyroxenes, ferroan olivine, Fe-Ti (and possibly Cr) oxides, phosphate, and possibly glass. The texture of Wishstone is consistent with a pyroclastic origin, whereas Irvine and Backstay are lavas or possibly dike rocks. Chemical compositions of these rocks plot on or near liquid lines of descent for most elements calculated for Adirondack class rocks (olivine-rich basalts from the Gusev plains) at various pressures from 0.1 to 1.0 GPa. We infer that Wishstone-, Backstay-, and Irvine-class magmas may have formed by fractionation of primitive, oxidized basaltic magma similar to Adirondack-class rocks. The compositions of all these rocks reveal that the Gusev magmatic province is alkaline, distinct from the subalkaline volcanic rocks thought to dominate most of the planet's surface. The fact that differentiated volcanic rocks were not encountered on the plains prior to ascending Husband Hill may suggest a local magma source for volcanism beneath Gusev crater. Copyright 2006 by the American Geophysical Union.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Alkaline volcanic rocks from the Columbia Hills, Gusev crater, Mars
Series title:
Journal of Geophysical Research E: Planets
DOI:
10.1029/2006JE002698
Volume
111
Issue:
9
Year Published:
2006
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Geophysical Research E: Planets