地质论评2009，Vol.55Issue(5)：673-684,12.
浙东南石平川花岗岩体LA-ICP-MS锆石U-Pb年代学及构造意义
Zircon U-Pb Dating and Tectonic Significance of the Shipingchuan Granite in Southeastern Zhejiang Province, SE China
摘要
Abstract
The Shipingchuan K-feldspar granite is situated in south-central volcanic belt of southeastern Zhejiang Province. LA-ICP-MS zircon U-Pb dating yields a weighted mean ~(206)Pb/~(238)U age of 102.5±1.2 Ma (MSDW=2.1)for the Shipingchuan granite intrusion,implying its end of early Cretaceous crystallization time. Petrography and chemical compositions show that it belongs to high-K calc-alkaline series characterized by high silicon,enriched in kalium and aluminum but depleted in iron,magnesium,phosphorus and titanium.SiO_2 and K_2O contents range from 74.79% to 77.79% and 4.26% to 7.97% respectively. A/CNK values vary from 0.98 to 1.10,indicating a metaluminous to weakly peraluminous character. The rocks are enriched in Rb,Th,U and K,but depleted in Sr,Ba,Nb,P and Ti. REEs are characterized by intermediate negative Eu anomalies with Eu/Eu* =0.33~0.50 and exhibit right-dipping "V" patterns with LREE enrichment. [n(~(87)Sr)/n(~(86)Sr)]I and ε_(Nd)(t) values (t=102.5Ma)of the Shipingchuan intrusion range from 0.70801 to 0.71012 and -8.76 to -8.63 respectively,showing the intrusion is the result of mixing by crustal and mantle materials.Mineralogy and geochemistry suggest that the Shipingchuan K-feldspar granite intrusion is a highly fractionated I-type granite. Trace elements features display that the pluton was a post-collisional granite and formed in an extensional tectonic setting in the end of early Cretaceous. These results indicate the Shipingchuan granite is related to back-arc extension due to high angle subduction of the paleo-Pacific plate,caused by northward movement of Indian plate.关键词
LA-ICPMS锆石U-Pb年代/高演化I型花岗岩/弧后伸展/石平川花岗岩/浙江Key words
LA-ICP-MS zircon U-Pb dating/ highly fractionated I-type granite/ back-arc extension/ the Shipingchuan granite/Zhejiang province分类
天文与地球科学引用本文复制引用
李艳军,魏俊浩,姚春亮,鄢云飞,谭俊,付乐兵,潘锦勃,李伟..浙东南石平川花岗岩体LA-ICP-MS锆石U-Pb年代学及构造意义[J].地质论评,2009,55(5):673-684,12.基金项目
本文为教育部创新团队发展计划(编号IRT0755)、全国危机矿山接替资源找矿项目(编号 2006020035)及中国地质大学地质过程与矿产资源国家重点实验室基金资助项目的成果. （编号IRT0755）
