Title: Identification of the Early Devonian Shuangfengshan A-type granites in Liuyuan area of Beishan and its implications to tectonic evolution
Abstract:Lots of early-middle Paleozoic granitoids occur in Liuyuan area of Beishan.The Shuangfengshan granitic pluton in Liuyuan is characterized by high Si,alkali(AR=3.99~5.05,NK/A0.85),FeOT/MgO and 10 000×G...Lots of early-middle Paleozoic granitoids occur in Liuyuan area of Beishan.The Shuangfengshan granitic pluton in Liuyuan is characterized by high Si,alkali(AR=3.99~5.05,NK/A0.85),FeOT/MgO and 10 000×Ga/Al values,and low Al2O3,CaO and MgO content,showing metaluminous and alkali features.The granites show high REE,slight richness of LREE,a weak fractionation between LREE and HREE,and an evidently negative Eu anomaly.They are enriched in Rb,Th,Zr and Hf,strongly depleted in Ba,Sr,P,Eu and Ti,and slightly depleted in Ta and Nb.These rocks also have high Rb/Nb and Y/Nb ratios,implying the aluminous A2-type granite.The LA-ICP-MS zircon U-Pb dating yielded a 206Pb/238U age of 415±3 Ma(MSWD=1.5),considered to be the emplacement age of the Shuangfengshan granitic pluton.All these geochemical features indicate that these granites probably resulted from the earlier calc-alkaline granitic magmas which might crystallized from differentiation of granodioritic magmas formed by partial melting of continental crust(oceanic crust and island arc) due to the underplating of the mantle-derived magma.Based on characteristics of outcrops,chronology,geochemistry and geological setting,the authors hold that the Shuangfengshan granitic pluton might be a post-orogenic or late stage orogenic pluton.The Early Devonian Shuangfengshan A-type granite is the oldest A-type granitic pluton ever found in Beishan,which provides important information for the researches on magmatic and tectonic evolution.Read More
Publication Year: 2009
Publication Date: 2009-01-01
Language: en
Type: article
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Cited By Count: 36
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