NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Petrology and Geochemistry of a Mg- and Al-Rich Orthopyroxenite Xenolith in the EETA79001 Shergottite: Implications for Mars Crustal EvolutionEETA79001 is a Mars meteorite (SNC) consisting of multiple rock types, including two basalt types, olivine and pyroxene xenocrysts, and ultramafic xenoliths. This study is focused on the petrology and geochemistry of one orthopyroxenite xenolith in PTS 68, designated X-1. It consists of chemically homogeneous orthopyroxene cores with exceptionally high Mg/Fe (mg#=85) and Al. Cores are permeated by minute high-Si+Al glassy inclusions, some with augite microlites. Magnesian core areas are mantled by more Fe-rich orthopyroxene rims grading to pigeonite away from cores. The xenolith is transected by cross-cutting shear planes, some of pre-incorporation origin. Major and minor element composition and variation suggest that core areas are primarily igneous, crystallized from a high temperature mafic melt. However, nearly constant mg# across cores suggest metamorphic equilibration. Si+Al inclusions may result from, among other processes, exsolution of feldspathic material during subsolidus cooling, or may be solid materials (alkali feldspar) poikilitically enclosed by growing igneous orthopyroxene crystals. Late reaction with more fractionated melts produced Fe-rich mantles, the whole assemblage later cut by tectonic micro-shear planes. Raw electron microprobe data produced during this study are available on request from the author.
Document ID
19990063444
Document Type
Other
Authors
Berkley, John L. (State Univ. of New York Fredonia, NY United States)
Date Acquired
August 19, 2013
Publication Date
May 1, 1999
Publication Information
Publication: National Aeronautics and Space Administration (NASA)/American Society for Engineering Education (ASEE) Summer Faculty Fellowship Program, 1998
Volume: 1
Subject Category
Geophysics
Funding Number(s)
PROJECT: RTOP 344-31-20-18
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

Related Records

IDRelationTitle19990063441Analytic PrimaryNational Aeronautics and Space Administration (NASA)/American Society for Engineering Education (ASEE) Summer Faculty Fellowship Program, 1998
Document Inquiry