苏鲁造山带南缘临沭县二长花岗岩成因  

Petrogenesis of the Linshu Monzonitic Granite in the Southern Part of the Sulu Orogen

作　　者：丁伟 王涛[1,2] 李彦波[3] 张硕 DING Wei;WANG Tao;LI Yan-bo;ZHANG Shuo(Key Laboratory of Tectonic Controls on Mineralization and Hydrocarbon Accumulation, Ministry of Land and Resource, Chengdu University of Technology, Chengdu 610059, China;State Key Laboratory of Ore De-posit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China;No.5 Geological Party, Xizang Bureau of Geology and Mineral Resources, Golmud Qinghai 816000, China)

机构地区：[1]成都理工大学国土资源部构造成矿成藏重点实验室,成都610059 [2]中国科学院地球化学研究所、矿床地球化学国家重点实验室,贵阳550081 [3]西藏自治区地质矿产局第五地质大队,青海格尔木816000

出　　处：《矿物岩石地球化学通报》2018年第2期344-354,共11页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家自然科学基金青年基金项目(41103017);矿床地球化学国家重点实验室开放基金项目(201105)

摘　　要：为探讨苏鲁造山带南缘临沭县青云镇地区二长花岗岩体的形成时代、岩石类型、源区性质、成岩构造环境及形成机制,对其开展了锆石U-Pb年代学及主微量元素地球化学分析研究。结果表明,LA-ICP-MS锆石U-Pb定年测得二长花岗岩成岩年龄为（126.6±3.8）Ma。岩体具高硅、弱过铝质、贫铁镁及富碱高钾的特征,稀土配分模式高度分异,亏损Nb、Ta、Ti、P等HFSE,相对富集Rb、Th、K、La等LILE和Pb元素,具中等弱Eu负异常,δEu主要分布在0.62-0.72。研究认为,该岩体可能主要来源于中等压力下（0.8-1.3 GPa）,深度为35-45 km的麻粒岩相下地壳的部分熔融,形成于拉张的构造环境。在成岩过程中可能存在矿物的分离结晶作用。岩石圈的拆沉和地幔岩浆的底侵作用可能是导致下地壳物质部分熔融的主要原因。In order to discuss the age,type,source,tectonic environment and formation mechanism of the Linshu monzonitic granite pluton,which is tectonically occurred in the southern part of the Sulu orogenic belt,in Qingyun Town,Linshu County,the zircon U-Pb dating,petrology and elemental geochemistry of the rock have been undertaken in this study.The results show that the LA-ICP-MS zircon U-Pb age of the monzonitic granite is（ 126. 6±3. 8） Ma. The rocks are characterized with high Si,weak peraluminous,poor Fe and Mg,rich alkaline and high K,and low TFeO/MgO ratios. In addition,the rocks are depleted in HFSE including Nb,Ta,Ti,and P and relatively enriched in Pb and LILE including Rb,Th,K,and La,with highly differentiated REE distribution patterns which have moderate Eu negative anomalies（ δEu= 0. 62-0. 72）. Therefore,it is believed that the rocks could be mainly derived from the partial melting of the lower crust of granulite facies under the moderate pressure（ 0. 8-1. 3 GPa）,corresponding the depth of 35-45 km,in an extensional tectonic environment. In the diagenetic process,the mineral fractional crystallization could be occurred. The detachment of the lithosphere and the underplating of the mantle magma could be mainly resulted in the partial melting of the lower crustal material.

关 键 词：苏鲁造山带 元素地球化学 部分熔融 下地壳物质 

分 类 号：P588[天文地球—岩石学]