摘要
Baidaban granite pluton in the Baidaban area of North Qilian Mountain mainly consisted of monzonite granite. Chemical analysis of rocks showed that these rocks are characteristic of high SiO2(63.66%~74.38%) and K2O/Na2O(2.61~3.31), and low aluminous, belonging to high K calc-alkaline granite series. The normalized REE-patterns revealed LREE enrichment with unconspicuous Eu negative abnormity (δEu=0.61~0.82). Multi-element normalized spider diagrams showed that they were rich in LILE (Rb, Th, K) and poor in HFSE (Y, Yb, Ta and Nb), similar to the typical continent-continent syn-collisional granite. These geochemical characteristics were similar to syn-collisional granites of occurred in Jinfosi of northern Qilian with a U-Pb ages of (414±4) Ma. It was considered that the tectonic setting of this pluton belonged to syn-collision accompanied by granite melting from lower crust.