The conditions at which monazite and allanite were produced and destroyed during prograde metamorphism of pelitic rocks were determined in a Buchan and a Barrovian regional terrain and in a contact aureole, all from northern New England, USA. Pelites from the chlorite zone of each area contain monazite that has an inclusion-free core surrounded by a highly irregular, inclusion-rich rim. Texture...

Please cite this article in press as: Schaefer, L., Fe implications for the composition of asteroids. Ic We used chemical equilibrium calculations to model thermal metamorphism of ordinary chondritic material as a function of temperature, pressure, and trace element abundance and use our results to discuss volatile mobilization during thermal metamorphism of ordinary chondrite parent bodies. We...

The Madurai block, the largest crustal block in Precambrian Southern Granulite Terrane of south India, preserves rare assemblages high- to ultrahigh-temperature metamorphic rocks. These rocks bear exclusive evidence for high thermal regime prevalent during their formation and can be constrained from accessory phases such as zircon, monazite garnet. Here, we present P-T-t evolutionary history ga...

Abstract About half of the lunar meteorites in our collections are feldspathic breccias. Acquiring geochronologic information from these breccias is challenging due to their low radioactive‐element contents and often polymict nature. We used high‐spatial‐resolution (5 μm) NanoSIMS (nanoscale secondary ion mass spectrometry) U‐Pb dating technique date micro‐zircons Dhofar 1528 1627. Three spots ...

Empirical tests of oxygen exchange rate in zircon crystals from amphiboliteand granulite-facies metamorphic rocks of the Grenville Province demonstrate preservation of igneous dO through protracted igneous and metamorphic histories, forming the basis of quantitative estimates of diffusion rate. Granitic orthogneisses, which cooled slowly after granulite-facies metamorphism, show no consistent r...

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...

Studies of several samples of the large Caddo County IAB iron meteorite reveal andesitic material, enriched in Si, Na, Al and Ca, which is essentially unique among meteorites. This material is believed to have formed from a chondritic source by partial melting and to have further segregated by grain coarsening. Such an origin implies extended metamorphism of the IAB parent body. New 39Ar40Ar ag...