Paleoproterozoic Collisional and Intraplate Granitoids of the Southwest Margin of the Siberian Craton: Petrogeochemical Features and U-Pb Geochronological and Sin-Nd Isotopic Data

摘要

Accretion of the Archean blocks of the continental crust 1.95-1.90 Ga ago that caused the formation of the Paleoproterozoic supercontinent Pangea I [1] was accompanied by metamorphism and intensive granite formation in collisional orogenes. Paleoproterozoic collisional granitoids are widely represented in the uplifts of the Eurasian platform basement: on the Ukrainian, Anabar, and Aldano-Stanovoi shields as well as along the southwestern margin of the Siberian craton. They form extended belts consisting of dominating post-tectonic microcline granites with minor tonalities, granodiorites and quartz syenites predominantly of sodium-potassium calc-alkaline magmatic series. Their characteristic feature is enrichment by large-ionic and high field strength elements, light lan-thanoids, uranium, and especially thorium [2].