Introduction: The mesosiderites are amongst the most enigmatic of all the meteorite groups and their formation is not fully understood. Evidence taken from both the metal and silicate portions indicates that they have a multi-stage formation history [1,2]: 1. Initial crystallization and cooling of silicates, followed by brecciation on the surface of the parent body 2. Metal-silicate mixing, som...

The CI and CI-like chondrites provide a record of aqueous alteration in the early solar system. However, the CI-like chondrites differ in having also experienced a late stage period of thermal metamorphism. In order to constrain the nature and extent of the aqueous and thermal alteration, we have investigated the bulk mineralogy and abundance of H2O in the CI and CI-like chondrites using thermo...

, ABSTRACT Metabasaltic rocks in the Klamath Mountains of California with 'komatiitic' major element concentrations were investigated in order to elucidate the origin of the magnesian signature. Trace-element concentrations preserve relict igneous trends and suggest that the rocks are not komatiitic basalts, but im~at~re arc rocks and within-plate alkalic lavas. Correlation of 'excess' MgO with...

U-Pb and Ar/Ar dates from the Talladega belt, southernmost Appalachians, provide insight into the timing and nature of pre-Alleghanian tectonism in this region. Low-grade metasedimentary rocks of the Talladega belt represent the outermost preserved portions of the southern Laurentian margin, thus recording the earliest orogenic events that affected the margin, in addition to later overprinting ...

Infrared laser probe Ar/Ar geochronology, instrumental neutron activation analysis (INAA) and analytical electron microscopy have been performed on four 0.5 1.0 0.3 cm polished rock tiles of Apollo 16 and 17 granulitic breccias (60035, 77017, 78155, and 79215). Pyroxene thermometry indicates that these samples were re-equilibrated and underwent peak metamorphic sub-solidus recrystallization at ...

Between the western and the eastern parts of the southern Alaskan Sanak–Baranof belt there exist variations in pluton spacing, geochronology, geochemistry and metamorphism. All such characteristics can be explained by increase in heat flux towards the eastern parts of the belt. Despite such differences, the initiation of magmatism propagated eastward at a constant rate of 19 cm/year throughout ...

The key to comprehending the tectonic evolution of the Himalaya is to understand the relationships between large-scale faulting, anatexis, and inverted metamorphism. The great number and variety of mechanisms that have been proposed to explain some or all of these features re ̄ects the fact that fundamental constraints on such models have been slow in coming. Recent developments, most notably in...

Alteration and Shock Metamorphism. M. Komatsu, T. J. Fagan, A. Yamaguchi, T. Mikouchi, M. Yasutake, and M. E. Zolensky SOKENDAI, The Graduate University for Advanced Studies, Kanagawa, Japan ([email protected]), Dept. Earth Sciences, Waseda University, Japan, National Institute of Polar Research (NIPR), Japan, Dept. Earth and Planetary Science, The University of Tokyo, Japan, ARES, NA...