阿拉善地块南缘志留纪花岗闪长岩LA-ICP-MS锆石U-Pb年龄及地球化学特征  

LA-ICP-MS zircon U-Pb dating and geochemical characteristics of the Silurian granodiorite in the southern margin of Alxa Block, China

作　　者：王梓桐 王根厚[1] 张维杰[1] 王行军 WANG Zitong;WANG Genhou;ZHANG Weijie;WANG Xingjun(School of Geosciences and Resource,China University of Geology,Beijing 100083,China;The 21st Century Space Technology Application Co.,Ltd.,Beijing 100096,China;China Coal Geology Group Co.,Ltd.,Beijing 100040,China)

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]二十一世纪空间技术应用股份有限公司,北京100096 [3]中煤地质集团有限公司,北京100040

出　　处：《成都理工大学学报（自然科学版）》2022年第5期586-600,共15页Journal of Chengdu University of Technology: Science & Technology Edition

基　　金：中国地质调查局区域地质调查项目(1212011120717,1212011120706)。

摘　　要：探讨阿拉善地块南缘早古生代地质构造演化历史。通过对达里克庙花岗闪长岩LA-ICP-MS锆石U-Pb年龄、地球化学特征研究,获得成岩年龄为442.9±1.3 Ma、432.5±1.2 Ma;全岩主元素及痕量元素地球化学特征显示,为中钾-高钾钙碱性系列岩石,具有高Mg#、CaO、Na_(2)O和低K_(2)O的特点,稀土元素配分曲线为向右陡倾的“W”形曲线,富集大离子亲石元素Rb、Sr、Ba。达里克庙花岗闪长岩属于I型花岗岩、TTG岩类MA系列的高压型TTGG亚类花岗岩,形成于年轻的较热的洋壳俯冲带,是北祁连洋向阿拉善地块之下俯冲的产物。达里克庙花岗闪长岩形成于早志留世,由此推断北祁连洋至少从早志留世已开始向北俯冲。The early Paleozoic geological tectonic evolution history of the southern Alxa Block is discussed through the study of LA-ICP-MS zircon U-Pb dating and geochemical characteristics of the Dalikemiao granodiorite.LA-ICP-MS zircon U-Pb dating for the Dalikemiao granodiorite yields the ages of 442.9±1.3 Ma and 432.5±1.2 Ma respectively,indicating that the rock mass was formed in early Silurian period.The geochemical characteristics of main elements and trace elements in the whole rock show that the rocks are medium-high potassium calc-alkaline series with high Mg#,CaO,Na_(2)O and low K_(2)O.The REE distribution curves are W-shaped with steep right inclination,and the rocks are enriched in large ion lithophile elements,such as Rb,Sr and Ba.The Dalikemiao granodiorite belongs to I type granite,TTGG subtype granite of TTG MA series,formed in the young and hot oceanic crust subduction zone,and was the product of the subduction of north Qilian Ocean to Alxa Block.Since the Dalikemiao granodiorite was formed in the early Silurian,it can be inferred that the North Qilian Ocean has been subducted northward since at least the early Silurian.

关 键 词：阿拉善地块 达里克庙 花岗闪长岩 锆石U-PB年龄 志留纪 

分 类 号：P588.12[天文地球—岩石学]