碎屑锆石微量元素对物源区的指示:以辽东半岛辽河群为例  

Trace Element Compositions in the Detrital Zircons as an Indicator of Source Rock Type:An Example from Liaohe Group in the Liaodong Peninsula,Northeast China

作　　者：王家林[1,2] 李壮[1,2] 

机构地区：[1]北京大学地球与空间科学学院,北京100871 [2]北京大学造山带与地壳演化教育部重点实验室,北京100871

出　　处：《地质科技情报》2017年第2期36-50,57,共16页Geological Science and Technology Information

基　　金：科技部973项目(2012CB416603);国家自然科学基金重点项目(90914001);北京大学开放测试基金(0000010541);吉林大学大学生创新性实验计划项目(2010C61164)

摘　　要：碎屑锆石U-Pb年代学方法已被广泛用于物源分析,但其微量元素数据很少被利用。系统地总结了不同成因锆石的微量元素特征,并对碎屑锆石微量元素数据的应用做了详细介绍,进而探讨了碎屑锆石微量元素对物源区的指示意义。以碎屑锆石微量元素综合研究为基础,结合碎屑锆石年代学的解释,系统分析了辽东半岛辽河群物源区的特征。辽河群沉积岩中2.2~2.1Ga的碎屑锆石主要来自于花岗岩类,与区域上胶-辽-吉活动带内出露的花岗岩类和同时期的酸性火山岩相吻合;而2.1~2.0Ga岩浆事件虽并未在地表大量出露,但碎屑锆石微量元素显示该期年龄的碎屑锆石主要来自于花岗岩类,其次是基性岩。辽河群沉积岩的碎屑锆石微量元素研究不仅验证了碎屑锆石微量元素用于物源分析的可行性,而且对2.1~2.0Ga岩浆事件的性质提供了制约,为胶-辽-吉活动带的形成演化提供了新的依据。Although the U-Pb dating of detrital zircons has been already widely used in sedimentary prove- nance studies, trace element characteristics of zircons are seldom utilized. In this paper, we present a sys- tematic study on the trace element compositions of zircons with different genesis and introduce a method of zircon trace element analyses, so as to discuss the indicating significance of the trace elements. Based on the integrated researches of detrital zircon trace elements, as well as the explanation of detrital zircon geo- chronology, we analyzed systematically the provenance of Liaohe Group in the Liaodong Peninsula, north- east China. On the discriminant diagrams, zircons with the ages of 2.2--2.1 Ga are mainly sourced from the granitoids, which are consistent with the formation of regionally distributed granitoids and coeval vol- canic rocks in the Jiao-Liao-Ji Belt. However, detrital zircon trace elements diseriminant diagrams show that the age of 2.1--2.0 Ga mainly comes from the granitoids, with minor contributions from the mafic rocks. Evidently, 2.1--2.0 Ga magmatic event was not exposed on the surface. The analyses of trace ele- ment chemistry of detrital zircons not only reveal the potential of using zircon trace element characteristics to infer the rock types in sediment source regions, but also provide constraints on the nature of the 2.1-- 2.0 Ga magmatic events and the evolution of the Jiao-Liao-Ji Belt.

关 键 词：碎屑锆石 微量元素 物源 辽河群 

分 类 号：P597[天文地球—地球化学]