佳木斯地块林口地区早古生代花岗质岩石的成因及构造背景  

Petrogenesis and tectonic setting of Early Paleozoic granitoids in Linkou area,Jiamusi Block

作　　者：井佳浩 杨浩[1] 高妍 兰丽雪 吴浩然 JING Jia-hao;YANG Hao;GAO Yan;LAN Li-xue;WU Hao-ran(College of Earth Sciences,Jilin University,Changchun 130061,China;International Centre for Geoscience Research and Education in Northeast Asia,Jilin University,Changchun 130026,China)

机构地区：[1]吉林大学地球科学学院,长春130061 [2]吉林大学东北亚国际地学研究与教学中心,长春130026

出　　处：《世界地质》2021年第3期547-559,共13页World Geology

基　　金：国家自然科学基金青年科学基金项目(41802049)。

摘　　要：对佳木斯地块林口县大二龙村地区花岗质岩石进行岩相学、年代学及全岩地球化学研究,探讨其形成时代、岩石成因及构造背景。该地区岩石类型为花岗闪长岩与碱长花岗岩,LA-ICP-MS锆石U-Pb测年结果显示其形成时代为早古生代,年龄分别为531 Ma和501 Ma。地球化学分析结果显示其具有高硅、富碱,贫钙、铁、镁的特点,富集Rb、K等大离子亲石元素,Th、U等高场强元素,亏损Nb、Ta、Ti等高场强元素及P元素。花岗闪长岩与碱长花岗岩分别为中高钾钙碱性I型花岗岩和碱性系列高分异I型花岗岩。两者均起源于下地壳物质的部分熔融,在岩浆演化过程中经历了不同程度的分离结晶。综合本文数据以及区域研究成果,认为佳木斯地块早古生代岩浆活动形成于麻粒岩相峰期变质作用之后,由加厚地壳垮塌造成的伸展构造背景。The petrographical,geochronological and whole-rock geochemical data for the granitoids in the Daerlongcun area of the Jiamusi Block have been presented,with the aim of evaluating their formation age,petrogenesis and tectonic setting.The studied granitoids are composed mainly of granodiorite and alkali-feldspar granite.The LA--ICP--MS zircon U--Pb dating shows that the granodiorite and alkali-feldspar granite formed during the Early Paleozoic,with ages of 531 Ma and 501 Ma,respectively.Geochemically,they are characterized by high concentrations of SiO 2,Na 2O+K 2O,but low concentrations of total Fe 2O 3,CaO and MgO.They are enriched in large-ion lithophile elements(LILEs;e.g.,Rb,K)and high-field-strength elements(HFSEs;e.g.,Th,U),but depleted in HFSEs(e.g.,Nb,Ta,Ti)and P.The granodiorite and alkali-feldspar granite belong to the middle-high-K calc-alkaline I-type and highly fractionated I-type granites,respectively.Both of them were derived from the partial melting of a lower crust and subsequently underwent some degrees of fractional crystallization processes.Along with the regional geological data,the authors propose that the Early Paleozoic magmatic rocks in the Jiamusi Massif were emplaced in a post-collisional extensional setting,which was closely related to the collapse of the thickened crust after the peak granulite facies metamorphism.

关 键 词：佳木斯地块 早古生代 花岗质岩石 地球化学 岩石成因 

分 类 号：P595[天文地球—地球化学] P597[天文地球—地质学]