地质通报2016，Vol.35Issue(5)：687-699,13.
东昆仑东段香日德地区察汗陶勒盖正长花岗岩LA-ICP-MS锆石U-Pb年龄及其地质意义
LA-ICP-MS zir-con U-Pb dating of the Chahantaolegai syenogranites in Xiangride area of East Kunlun and its geological significance
摘要
Abstract
A suite of syenogranites is exposed in the Chahantaolegai area along the eastern section of East Kunlun Orogenic Belt. LA-ICP-MS zircon U-Pb weighted average ages is 239.9 ± 0.7Ma, suggesting the formation of syenogranites in Middle Triassic. According to the geochemical characteristics, it is suggested that Chahantaolegai syenogranites belong to peraluminous high-potassic calc-alkaline series. They are characterized by high SiO2, Al2O3, K2O and low TiO2 and Na2O values. A/CNK=1.05~1.13 (average A/CNK=1.10), K2O/Na2O ratios are about 0.95~1.16, and Rittmann indexσ=1.56~2.24;the content of corundum exceeds 1%, as shown by CIPW standard mineral calculation. The existence of rock-forming minerals such as muscovite suggests that the syenogran⁃ites are of S-type. The values of rare earth elements are 61.47 × 10-6~145.23 × 10-6. The chondrite-normalized REE patterns of the samples show enrichment of LREE((La/Yb)N=15.83~27.11)and strong negative Eu anomalies(δEu=0.26~0.49). The primitive mantle-normalized trace element diagrams show enrichment of Rb, La and Th and depletion of Ba, Ta, Sr, P and Ti. Characteristics of trace and earth elements suggest that syenogranites were from the earth's crust. It is suggested that the syenogranites resulted from melting of the sedimentary rocks of the upper crust. Combined with regional studies, the authors hold that Chahantaolegai syenogran⁃ites are of the transitional type formed in the transformation from subduction to syn-collision, being a product of the late stage of the subduction of Buqinshan-A’nyemaqen Ocean on the southern margin of the East Kunlun in Middle Triassic.关键词
东昆仑东段/正长花岗岩/中三叠世/LA-ICP-MS锆石U-Pb测年/俯冲造山Key words
East section of East Kunlun/syenogranites/Middle Triassic/LA-ICP-MS zircon U-Pb dating/subduction orogeny分类
天文与地球科学引用本文复制引用
邓文兵,桑继镇,王旭斌,裴先治,刘成军,李佐臣,李瑞保,陈有炘,陈国超,杨森,陈功..东昆仑东段香日德地区察汗陶勒盖正长花岗岩LA-ICP-MS锆石U-Pb年龄及其地质意义[J].地质通报,2016,35(5):687-699,13.基金项目
国家自然科学基金项目（批准号41472191、41502191、41172186）、高等学校博士学科点专项科研基金项目（编号20110205110004）和中央高校基本科研业务费专项资金项目 （）
