Introduction: Although some CR chondrites are recognized to be among the most pristine meteorites [1], other members of this group are heavily hydrated [e.g. 2]. However, no evidence of thermal metamorphism has been documented for this group. Antarctic fall GRA 06100, initially classified as a CR2 chondrite have not been previously studied. We use optical microscopy, SEM, and focused beam EPMA ...

A lot of troilite reaction rim textures formed through sulfidation of FeNi alloy of kamacite and taenite with sulfur rich gas have been identified especially in C03 unequilibrated carbonaceous chondrites. Troilite formation through sulfidation of FeNi alloy of kamacite and taenite with sulfur rich gas in the solar nebula is expected from the reaction kinetics as well as from the equilibrium con...

Metapelites collected in central Nepal reveal a discontinuity in metamorphic pressuretemperature-time (P-T-t) paths near the base of the Main Central thrust zone, despite an absence of obvious structural breaks. Garnets in the structurally lowest rocks grew with increasing T and P (loading), whereas garnets 1–3 km upsection grew with increasing T, but decreasing P (exhumation). Monazite grains ...

The study of short-lived, now extinct radionuclides offers constraints on the duration of planetesimal formation and on other processes and events, which took place in the early solar system. The relative chronometers based on the decay of 53Mn to 53Cr (T1/2 = 3.7 m.y.) and of 26Al to 26Mg (T1/2 = 0.73 m.y.) provide an adequate time resolution of at least 1 m.y. A calibration of these relative ...

ABSTRACT This paper presents and discusses the results of phase diagram (Perple_X) diffusion modelling (CZGM, or Compositional Zoning its Modification by diffusion) to constrain P–T path metamorphism. The approach is based on best fits between zoning profile in measured garnet that obtained intersections isopleths calculated using whole rock bulk composition. model was applied garnets natural r...

A garnetite that occurs locally in phyllitic schists exposed by the Santorini caldera consists mainly of euhedral garnet crystals showing alternating isotropic and birefringent lamellae. X-ray diffraction revealed two garnets with unit cell dimensions a of I2.o52:ko-oo2 and I~'984-ko-oo5 A, corresponding respectively to almost pure andradite and a granditic phase. Mean compositions determined b...

Chondritic meteorites, consisting of the materials that have formed in the early solar system (ESS), have been affected by late thermal events and fluid activity to various degrees. Determining the timing of fluid activity in ESS is of fundamental importance for understanding the nature, formation, evolution and significance of fluid activity in ESS. Previous investigations have determined the ...

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...