COMPARATIVE GEOCHEMISTRY OF GRANITOIDS AND METAMORPHIC COUNTRY ROCKS IN THE WESTERN ANGARA-VITIM BATHOLITH, WESTERN BAIKAL AREA

Abstract

This paper presents materials of granitoids from the western Angara-Vitim batholith and the country gneisses and migmatites of the Talanchan Metamorphic Complex. The granitoids of the older intrusive phases of the Barguzin Complex are characterized by high dispersions in the contents of most trace element. The similarities in their trace-element signatures to those of metavolcanics of the Talanchan Group indicate that the latter could have served as a source of the granitoid melts. The increase in the K, Rb, Sn, Be, and REE contents from granitoids of the older phase of the Barguzin Complex to the main phase of this complex and further to the granites of the Zazin Complex is a result of melt fractionation which simultaneously became more uniform and acquired Eu minima. The group of calc-alkaline diorites is identical in composition to the metavolcanics and probably complements the latter. Metagabbro of normal alkalinity and synplutonic subalkali gabbro of the Oshurkov type are distinguished by composition and the relationships with the country gneisses and granitoids. © Pleiades Publishing, Inc. 2006.