上扬子盆地西缘晚白垩世物源变化及指示  

Provenance change and its indication of Late Cretaceous in the west margin of Upper Yangtze Basin

作　　者：姜磊[1] 刘树根[1] 王自剑[1] 李智武[1] 赖东 何宇[1] 罗强 周政 邓宾[1] JIANG Lei;LIU Shugen;WANG Zijian;LI Zhiwu;LAI Dong;HE Yu;LUO Qiang;ZHOU Zheng;DENG Bin(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology,Chengdu, Sichuan,610059)

机构地区：[1]成都理工大学油气藏地质及开发工程国家重点实验室,成都610059

出　　处：《地质论评》2019年第2期477-490,共14页Geological Review

基　　金：四川省青年基金项目(编号:2017JQ0025);国家自然科学基金资助项目(编号:41572111;41402119和41472107)的成果

摘　　要：对上扬子盆地西缘的上白垩统—古近系剖面开展沉积构造研究、传统重矿物分析、金红石微量元素地球化学研究。研究发现:①晚白垩世晚期,柳嘉剖面出现中酸性岩浆岩指数(ATi)升高和中低级变质岩指数(GZi)升高,宜就剖面出现中酸性岩浆岩指数(ATi)升高;柳嘉剖面富含石榴子石是与宜就剖面最大的不同。②柳嘉剖面和宜就剖面金红石母岩类型均主要为泥质变质岩,以角闪岩相/榴灰岩相为主。晚白垩世晚期,柳嘉剖面麻粒岩相达到最大,为39%,宜就剖面麻粒岩相出现最小值,达到13%,上扬子盆地西缘的麻粒岩相变化趋势的差异是物源差异的一种表现。③上扬子盆地西缘的晚白垩世物源变化揭示出松潘—甘孜褶皱带和龙门山构造带在晚白垩世晚期发生大规模快速隆升剥蚀事件。Objectives: The Upper Cretaceous-Paleogene sections of Liujia area in the south of Sichuan Basin and of Yijiu area in the north of Chuxiong Basin have been studied,which purpose is to further understand the provenance change and tectonic activities in the western margin of the Upper Yangtze basin.Methods: We carried out some researches of the Upper Creteaceous-Paleogene sections by sedimentary structure,traditional heavy mineral analysis,and the geochemistry of rutile trace elements in the western margin of the Upper Yangtze basin.Results: The results show that:(1)In late Late Cretaceous,the medium-acid magmatic rock index( ATi) and the low-middle grade metamorphic rock index( GZi) increased in Liujia section, and the medium-acid magmatic rock index( ATi) increased in Yijiu section. Liujia section is rich in garnet mineral,which is the key difference from Yijiu section.(2) The types of rutile mother rocks in Liujia section and Yijiu section are mainly argillaceous metamorphic rocks,with amphibolite facies and eclogite facies as the main types. In the late Late Cretaceous,the granulite facies in Liujia section reached the maximum value of 39%,and the minimum value of granulite facies in Yijiu section reached 13%. The variation trend of granulite facies in the west margin of the Upper Yangtze basin is a manifestation of the provenance difference.Conclusions: The Late Cretaceous provenance changes in the western margin of the upper Yangtze basin revealed that a large-scale rapid uplift and denudation events occurred in the Songpan-Ganzi Fold Belt and Longmenshan Structural Belt in the late Late Cretaceous.

关 键 词：上扬子 重矿物 白垩系 物源 金红石 

分 类 号：P618.13[天文地球—矿床学] P534.53[天文地球—地质学]