Sm-Nd and Rb-Sr ages and P-T history of the Archean Sittampundi and Bhavani layered meta-anorthosite complexes in Cauvery shear zone, South India: evidence for Neoproterozoic reworking of Archean crust

Article Abstract:

Whole rock Sm-Nd isochrons for the Archean Sittampundi and Bhavani layered meta-anorthosite complexes in the Cauvery shear zone (CSZ), South India, yield concordant ages of around 2.9 billion years. The magmatic protoliths of these suites came from similar uniform and LREE depleted mantle sources. At least two episodes of high grade metamorphism are distinct, the latter being related to the transpressional tectonic events that resulted in shearing along the CSZ. The CSZ is defined as a zone of Neoproterozoic reworking of the Archean crust that occurred about 730 million years ago.

Geological time, Geochronology

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Sapphirine-bearing orthopyroxene-kyanite/sillimanite granulites from South Harris, NW Scotland: evidence for Proterozoic UHT metamorphism in the Lewisian

Article Abstract:

The first discovery of an orthopyroxene-aluminosilicate and sapphirine association in the Lewisian complex of South Harris in Scotland is presented. Sillimanite inclusions within orthopyroxene indicate that sillimanite formed earlier and may have existed earlier. The occurrence of accessory sapphirine in various assemblages with different compositions showed that it was formed at different stages of the metamorphism. Results demonstrate that the granulites were developed in the Early Proterozoic high-grade metamorphism.

Scotland, Natural history, Rocks, Metamorphic, Metamorphic rocks, Granulite

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Lead isotopes in sulfides from the Stillwater Complex, Montana: evidence for subsolidus remobilization

Article Abstract:

The possible genetic relationship between silicate minerals and sulfides is examined, focusing on the role of lead isotopes. Researchers discuss the possibility that radiogenic lead originated from minerals altered by low-temperature metamorphism.

Montana, Statistical Data Included, Lead, Composition, Isotopes, Sulfides, Silicate minerals

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