Contribution of Alkaline Granite Magmatism to the Formation of the Khangai Batholith: Geological and Geochronological Evidence

摘要

The world largest batholiths (Angara-Vitim, Khangai, and Khentei) each approximately 150000 km~2 in size and over 0.5 mln km~3 in volume are located in the Central Asian fold belt south of the Siberian Platform. These magmatic bodies were formed successively during a relatively short period between 300 and 200 Ma ago [ 1 ]. Their formation is thought to be related either to the convergence [2, 3] and development of the active margin of the Siberian paleocontinent or to activity of mantle plumes [1 ]. Both models are probable, although insufficiently substantiated.The concept of the significant role of mantle hot spots (mantle plumes) in the formation of Central Asian batholiths is based on data indicating their close relations with zonal magmatic area represented by rocks with intraplate geochemical characteristics [1]. The presence of such rocks within the batholiths provides direct evidence for the contribution of intraplate magma sources to the granite formation. At the same time, their contribution may be substantiated only by proving the synchronous formation of different igneous rocks [2-4].