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PYROXENES IN THE PATWAR MESOSIDERITE ‡
Author(s) -
Peter W. Weigand
Publication year - 1975
Publication title -
meteoritics
Language(s) - English
Resource type - Journals
eISSN - 1945-5100
pISSN - 0026-1114
DOI - 10.1111/j.1945-5100.1975.tb01191.x
Subject(s) - pigeonite , pyroxene , geology , plagioclase , geochemistry , chromite , basalt , igneous rock , petrography , electron microprobe , metamorphism , mineralogy , augite , olivine , quartz , paleontology
Major and minor elements were determined with the electron microprobe in pyroxene from Patwar, one of the least metamorphosed mesosiderites. All but two orthopyroxene crystal fragments fall in the range Wo 2.3 En 73 to Wo 3.9 En 59 , while pigeonite from a basalt clast clusters around Wo 13 n 38 . Absolute and relative amounts of Ti, Cr and Al are distinct from those in pyroxenes in irons‐with‐silicate‐inclusions. Zoning within ortho‐pyroxene grains suggests crystallization from an igneous melt in the presence of plagioclase and chromite, followed at some later time by brecciation and subsequent minor thermal metamorphism. Compositional data support petrographic evidence that the silicates in Patwar were derived from a heterogeneous source.