Constraints on Archaean crustal evolution of the Zimbabwe craton: a U-Pb zircon, Sm-Nd and Pb-Pb whole-rock isotope study

Article Abstract:

A geochronological study of felsic plutonic and volcanic rocks from northern Zimbabwe reveals the evolution of the Harare-Shamva granite-greenstone belt. U-Pb zircon dating, followed by Pb-Pb and Sm-Nd whole rock isotope study, suggests that deposition of greenstones on the Archaean basement gneisses occurred between 2715 plus or minus 15 million years ago (Ma) and 2672 plus or minus 12 Ma. Influence of granitoid intrusion on the evolution of the greenstone belt is discussed. Two rift-related models explain the causes of magmatic activity.

Usage, Measurement, Observations, Geology, Stratigraphic, Stratigraphy, Zimbabwe, Archean Eon, Radioisotopes, Zircon, Geology, Geological time, Geochronology, Radioisotopes in geology

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Two mantle sources, two plumbing systems: tholeiitic and alkaline magmatism of the Maymecha River basin, Siberian flood volcanic province

Article Abstract:

The changing properties of the volcanic rock types of the Maymecha River basin as well as the nature of their mantle sources, the conditions of mantle melting and the manner in which the resulting magmas traverse the crust and lithosphere were investigated. The volcanic sequence in the Maymecha River basin formed during a third magmatic episode. On the other hand, magmas of the alkaline series formed through melting deep in the mantle and rose to the surface along conduits that bypassed the large, open-system, crustal magma chambers.

Analysis, Siberia, Watersheds, Alkalic igneous rocks

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