Collisional granitoids of the Dzhida zone of the Central Asian Fold belt, Southwestern Transbaikalia: Age and conditions of the formation

Abstract

This paper considers the geological structure, composition, and age of the Darkhintui, Barun-Gol, and Khuldat granitoid plutons of the Dzhida zone of Caledonides of the Central Asian Fold belts. These plutons were formed in the Late Cambrian-Early Ordovician in the range between 490 ± 2 and 477 ± 6 Ma, after tectonic juxtaposition of the oceanic and island-arc complexes of the Dzhida Zone and volcanogenic-carbonate-terrigenous rocks of the Khamardaban zone, i.e., at the collisional stage of the region evolution. Geological, geochronological, geochemical, and Nd isotope data indicate that the collisional granitoids of the Dzhida zone were derived by melting of continental crust thickened through accretion. The sources for parental melts of the granitoids were presumably Vendian-Early Cambrian juvenile igneous rocks of ophiolite and island-arc complexes, as well as the crustal material of the Lower Paleozoic flyschoid sediments of the back-arc basin of the Dzhida zone and metaterrigenous rocks of the Khamardaban zone.