Archaean komatiites of the greenstone belt in Manica area, western Mozambique contains accessory amount of disseminated chromite grains. The komatiite rocks comprise peridotitic and basaltic komtiite. These komatiites are affected by regional metamorphism as all of the studied area. It is observed that only chromian spinel is preserved as the primary mineral and that all the other primary miner...

We present geochronological evidence in the eastern Himalayan syntaxis (Namche Barwa) for high-pressure (HP) granulite-facies metamorphism and explain its importance for understanding both the deep continental subduction of the Indian plate beneath Asia and its subsequent exhumation. The timing of peak and retrograde metamorphism in part constrains these processes but is debated. We present zir...

1. Introduction High-pressure minerals, produced by shock metamorphism, are common in and around melt veins in highly shocked chondrites [1-8]. These minerals either crystallized from silicate melt in the shock-vein or formed by solid-state transformed from host-rock fragments entrained in the melt or along shock-vein margins [3]. The study of these high pressure minerals can give us a better u...

Introduction: A recent paper on helium loss from Martian meteorites states that the high-pressure mineralogy of veins is not a good equilibrium pressure barometer.[1] We respectfully disagree. However we do agree with the authors that it is likely that helium loss from Martian meteorites is largely due to shock metamorphism. It is not certain that the shock metamorphism was coincident with the ...

Zircon (ZrSiO4) is the most commonly used geochronometer, preserving age and geochemical information through a wide range of geological processes. However, zircon U-Pb geochronology can be affected by redistribution of radiogenic Pb, which is incompatible in the crystal structure. This phenomenon is particularly common in zircon that has experienced ultra-high temperature metamorphism, where io...

Archean supracrustal sequences of pelitic, quartzitic, calcareous and mafic compositions in the central Laramie Mountains, Wyoming, have been affected by two metamorphic events: a 1.78 Ga amphibolitegrade regional metamorphism, and a 1.43 Ga contact metamorphism resulting from the intrusion of the Laramie Anorthosite Complex (LAC). Rb–Sr whole-rock isotopic data from both outside and within the...