南羌塘盆地江鱼玛洛地区中侏罗统雀莫错组砂岩地球化学及源区环境  

GEOCHEMISTRY AND SOURCE AREA ENVIRONMENT OF THE MIDDLE JURASSIC SANDSTONE IN SOUTHERN QIANGTANG BASIN

作　　者：徐琳[1] 肖进[1] 刘大明[1,2] 胡林[1] 罗绍强[1] 唐华[1] 赵宇 XU Lin;XIAO Jin;LIU Da-ming;HU Lin;LUO Shao-qiang;TANG Hua;ZHAO Yu(Northwest Sichuan Geological Team,Sichuan Bureau of Geology and Mineral Exploration and Development,Mianyang 621000,Sichuan Province,China;School of Earth Sciences,Chengdu University of Technology,Chengdu 610059,China;No.6 Geological Team,Tibet Bureau of Geology and Mineral Exploration and Development,Lhasa 851400,China)

机构地区：[1]四川省地质矿产勘查开发局川西北地质队,四川绵阳621000 [2]成都理工大学地球科学学院,四川成都610059 [3]西藏自治区地质矿产勘查开发局第六地质大队,西藏拉萨851400

出　　处：《地质与资源》2022年第6期738-747,797,共11页Geology and Resources

基　　金：中国地质调查局成都地质调查中心项目“羌塘盆地江鱼玛洛-多增木地区石油地质调查”(DD20160159-19).

摘　　要：南羌塘盆地江鱼玛洛地区发育中侏罗统雀莫错组,通过岩石地球化学分析,对砂岩源区环境进行恢复.化学风化作用指标(CIW)、化学蚀变作用指标(CIA)和A-CN-K图解反映砂岩的碎屑成分遭受过较强烈的风化.化学组分指标(ICV)和Th/Sc-Zr/Sc图解指示主要为第一沉积旋回产物,伴有少量沉积再循环物质.岩石元素Al_(2)O_(3)/TiO_(2)、Th/Sc、Cr/Zr比值和La/Th-Hf源岩判别图解反映砂岩的碎屑主要来源于上地壳长英质源区,并混入少量基性铁镁质岩石.砂岩的微量元素特征及SiO_(2)-K_(2)O/Na_(2)O、La-Th-Sc、Co-Th-Zr/10、Sc-Th-Zr/10判别图解均表明该砂岩形成于大陆边缘裂陷构造背景.The sandstone of Middle Jurassic Quemocuo Formation is developed in Jiangyumaluo area of southern Qiangtang Basin.The environment of sandstone source area is restored through petrogeochemical analysis.The chemical index of weathering(CIW),chemical index of alteration(CIA)parameters and A-CN-K diagram of sandstones show that the clastic compositions are intensely weathered.The index of compositional variability(ICV)and Th/Sc-Zr/Sc diagram indicate that the sandstone contains mainly the first sedimentary cycle materials,with a little recycled sediment.The Al_(2)O_(3)/TiO_(2),Th/Sc and Cr/Zr ratios of rock elements and La/Th-Hf discrimination diagram of source rocks suggest that the clastics of sandstone are mainly from the felsic source area of upper crust,mixed with a small number of basic femic rocks.The characteristics of trace elements and SiO_(2)-K_(2)O/Na_(2)O,La-Th-Sc,Co-Th-Zr/10,Sc-Th-Zr/10 diagrams all indicate that the sandstones were formed in the continental margin rifting tectonic setting.

关 键 词：雀莫错组 砂岩 地球化学 构造背景 南羌塘盆地 

分 类 号：P595[天文地球—地球化学]