A Comparative Study of Kaersutite in the Egersund Dikes and SNC Meteorites
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Date
2017-12
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The Ohio State University
Abstract
Martian meteorites aka SNC (Shergottite, Nakhla, Chassigny) meteorites, allow scientists the opportunity to study the interior of Mars. Petrologic examinations of Shergottite and Chassigny reveal an uncommon occurrence of the amphibole kaersutite. Kaersutite is usually found to crystallize in undersaturated alkaline basalts. It has been found in tholeiitic rocks in only two localities: melt inclusions in phenocrysts in the SNC meteorites, and in a melt inclusion in an olivine phenocryst in the Ol-tholeiitic Egersund dikes located in SW Norway. This study compares the bulk rock chemistry, kaersutite chemistry, and petrology of the SNC meteorites and the Egersund Ol-tholeiitic dikes. The phenocrysts that contain kaersutite in the Shergottite meteorites and the Egersund dikes display similar characteristics such as zoning, strain, and a skeletal texture, and both are interpreted as xenocrysts. However, SNC meteorites were ejected from Mars via impact events that exerted extreme pressure on the rocks, which complicates the petrologic interpretation. Olivine phenocrysts containing kaersutite in the Chassigny meteorites are not believed to be xenocrysts. Since Chassigny is a cumulate, much less about Chassigny’s host magma is known. REE (Rare Earth Elements) enrichment of the SNCs indicate that Mars is less differentiated than Earth, but similar geologic processes may still occur. Zonation of pigeonite, interpreted as two-stage magmatic evolution, and the bi-lithic nature of the Shergottites suggest that Martian magmatic processes are complex.
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SNC meteorites, kaersutite, Egersund Dikes, Chassigny, Shergottite, shocked meteorite