地质与勘探2017，Vol.53Issue(5)：889-902,14.
青海东昆仑东段加当辉长岩LA-ICP-MS锆石U-Pb测年及其地质意义
Zircon LA-ICP-MS U-Pb Dating and its Geological Significance of the Jiadang Gabbro in the Eastern Section of East Kunlun, Qinghai Province
摘要
Abstract
This paper presents a study on petrography, geochronology and geochemistry of the Jiadang gabbro in the eastern section of East Kunlun, Qinghai Province, which will furtehr the understanding of Paleo-Tethys tectono-magmatic evolution in East Kunlun. LA-ICP-MS zircon U-Pb dat-ingindicatesthattheweightedmeanageoftheJiadanggabbrois262.5±2.5Ma(n=38,MSWD=0.18),inthelateMiddlePermian. Petrogeochemical studies show that the gabbro, which belongs to the tholeiitic series, is characterized by low content of TiO2 (0. 79% ~1. 09%), P2 O5 (0. 06% ~0.09%),alkali(K2O+Na2O=1.99% ~2.39%),andNa2O>K2O. ThissuiteofrocksareenrichedinLILE(suchasRb,Ba,andK)andPb,and relatively depleted in HFSE (such as Nb, Ta, and P). The rocks have low REE content, with slightly positive Eu anomalies (∑REE=32.08 ×10 -6 ~46.41 ×10 -6, (La/Yb)N =1.59~2.00,δEu=0.95~1.32). The geochemical characteristics show that the parental magma of the gabbro is derived probably from the mantle. The parental magma was subject to crustal assimilation contamination during the magma evolution. Tectonic setting analysis shows that the Jiadang gabbro is an island arc magmatic rock formed in a subduction environment. Combining with tectonic evolution of East Kunlun, we consider that the Jiadang gabbro was the product of the northward subduction of the Anyemaqen-Paleo-Tethys ocean, providing a piece of new chrono-logical evidence for Late Paleozoic-Early Mesozoic tectonic evolution in East Kunlun.关键词
地球化学/锆石U-Pb定年/加当辉长岩/俯冲/东昆仑Key words
geochemistry/zircon U-Pb dating/Jiadang gabbro/subduction/East Kunlun分类
天文与地球科学引用本文复制引用
孔会磊,李金超,栗亚芝,贾群子,国显正..青海东昆仑东段加当辉长岩LA-ICP-MS锆石U-Pb测年及其地质意义[J].地质与勘探,2017,53(5):889-902,14.基金项目
国土资源大调查项目(编号DD20160013、12120115022101、12120113029000)联合资助. （编号DD20160013、12120115022101、12120113029000）
