Author:
Liu Yang,Fang Nianqiao,Song Chaojie
Abstract
Abstract
Vietnam is located between the Pacific subduction zone and Tethys orogenic belt. There are numerous Cretaceous granitoids in Vietnam, belonging quartz-diorite-granosyenite- granite-leucogranite magmatic series. According to geochemical data, granitoids are sub- alkaline. Samples in SV are calc-alkalic, with lower A/CNK and (Zr+Nb+Ce+Y) values, which belong to I-type granite. And those in NV are allali-calcic, with higher A/CNK values but lower (Zr+Nb+Ce+Y) values, which belong to S-type granite. Granitoids exhibit fractionated REE patterns with negative Eu anomalies, and show enrichment in LILEs and depletion in HFSEs. Because of the absence of alkaline dark-colored minerals, abundant intermediate igneous rocks and assemblage of I- and S-type granite with orogen-related geochemical characteristics, it is believed that there was compressive structure in Vietnam in Cretaceous due to Meso-Tethyan subduction.
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