Introduction: Primary igneous plagioclase is found in approximately 10 % of type I chondrules in CO chondrites [1]. The presence of plagioclase has potential to help interpret conditions of chondrule formation, if the conditions of plagioclase nuclea-tion and growth are understood. Because primary plagioclase typically contains a significant albite component, the presence of this mineral is sig...

Introduction: Lunar meteorite Dhofar 026 was previously interpreted as an impact melt [1, 2]. Detailed studies of the rock and comparison to Apollo lunar samples 15418 and 60017 indicate that the rock instead is a shocked, partly melted, granulitic breccia. These studies, presented by [3], are summarized herein. Petrology of Dhofar 026: Most of the rock consists of blocky patches of monomineral...

Introduction: Shock metamorphism is one of the most fundamental processes in the history of Martian meteorites. Especially, shergottites experienced strong shock effects (>30 GPa) most likely when they were ejected from Mars [e.g., 1]. " Maskelynitization " of plagioclase and formation of shock melts are major effects due to this severe shock. QUE94201 (QUE) and Dhofar 378 (DHO) are basaltic sh...

Introduction. Plagioclase feldspar has been identified as the dominant mineral phase in the martian crust [1-2] through analysis of Mars Global Surveyor Thermal Emission Spectrometer (TES) data. Martian meteorites , samples of isolated terrain on Mars, contain plagioclase in abundances secondary only to pyroxene. Terrestrial basalts and andesites contain primary plagioclase that is calcic-inter...

The ophiolites of Othris, northern Greece, and Troodos, Cyprus, are of mixed lherzolite-harzburgite and harzburgite sub-type respectively. Within both ophiolites an entire spectrum of harzburgite, plagioclase harzburgite, lhcrzolite and plagioclase lherzolite interpreted respectively as residual and highly, moderately and slightly modified upper mantle has been recognised. Plagioclase lherzolit...

Synneusis, the drifting together and systematic attachment of crystals in a melt, is involved in three of the known origins for mantled feldspars: (1) overgrowth, (2) exsolution, and (3) filling of skeletal plagioclase. Quartz latite dikes of the Chocolate Mountains, California, contain plagioclase crystals in parallel and twinned synneusis. Sanidine mantles consisting of segments, each crystal...

Major element compositions of glass inclusions in olivine and plagioclase phenocrysts from representative Mariana arc lavas show that mafic Mariana arc liquids are tholeiitic and not high-alumina, implying that the high-alumina characteristic of these lavas reflects accumulation of plagioclase. Glass inclusions also show the common occurrence of felsic melts previously unrecognized among Marian...

It is well known that oriented iron and titanium oxide inclusions occur in pyroxenes and plagioclase of anorthosites and granulites, and they are attributed to exsolution at subsolidus conditions. The oxides occur as needles or platelets. In this study, we determine the morphology of oxide needles as well as their orientation in plagioclase (An 30–35) in anorthosite gneiss from the Adirondack m...

A sequence of sixteen photomicrographs of thin sections of unaltered quartz diorite through a zone of deformation to myrmekite-bearing granite near Temecula, California, shows the textural and mineralogical changes that occurred in a quartz diorite as (1) K-metasomatism altered the primary plagioclase crystals to form microcline, myrmekite, quartz-bleb clusters, and recrystallized sodic plagioc...

A megacrystal granodiorite, occurring in a pluton in the Monterey peninsula of California, is gradational south to quartz monzonite and then to tonalite and trondhjemite and southeast to granodiorite and then to tonalite. A primary magmatic origin for the pluton is indicated by normally zoned plagioclase crystals and by dikes that extend into biotite-hornblende quartz diorite southeast of Point...