Age and Geochemistry of the Early Mesozoic Granitoid Massifs of the Southern Bureya Terrane of the Russian Far East

A massif of porhyritic microcline biotite granites located in the southern part of the Bureya (Turan) terrane has an age of 185 +/- 1 Ma. The granites are characterized by (K(2)O + Na(2)O) > 8%, a K(2)O predominance over Na(2)O, and a moderately differentiated REE distribution pattern ((La/Yb)(n) = 14.7-28.5). The obtained age indicates that at least one stage of the Early Mesozoic granitoid magmatism in the Bureya terrane occurred in the Early Jurassic. The formation of early Mesozoic granitoids was presumably related to collision between North Asian and Sino-Korean cratons, and the intervening Amur superterrane, although a subduction origin also cannot be completely ruled out.