Devonian-Carboniferous Pillow OIB-Type Basalts in the Youjiang Basin,SW China:Implications for the Eastern Extension of the Paleo-Tethys Branch Ocean  

作　　者：Jie Yang Yuansheng Du Hu Huang Jianghai Yang Hongwei Huang Zhiqiang Huang 

机构地区：[1]Shandong Provincial Key Laboratory of Water and Soil Conservation and Environmental Protection,School of Resources and Environment,Linyi University,Linyi 276000,China [2]State Key Laboratory of Biogeology and Environmental Geology,China University of Geosciences,Wuhan 430074,China [3]State Key Laboratory of Oil/Gas Reservoir Geology and Exploitation,Institute of Sedimentary Geology,Chengdu University of Technology,Chengdu 610059,China [4]General Academy of Geological Survey of Guangxi,Nanning 530023,China

出　　处：《Journal of Earth Science》2023年第3期690-705,共16页地球科学学刊（英文版）

基　　金：supported by the National Natural Science Foundation of China(No.41672106);China Postdoctoral Science Foundation(No.2020M672087)。

摘　　要：Late Paleozoic pillow basalts are well preserved in the Youjiang Basin of SW China.In this study,we conducted geochemical and Sr-Nd isotopic study on the Late Devonian and Late Carboniferous basalts in Napo area,Youjiang Basin.The analyzed samples comprise moderate SiO2,TiO2,Mg#,and REE contents,with slightly positive or negative Eu anomalies,similar to the chemical nature of OIB(Oceanic island basalt).All basalts show low(^(143)Nd/^(144)Nd)iand(^(87)Sr/^(86)Sr)ivalues,close to EMI-type(I-type Enriched Mantle)magma source.Late Carboniferous basalts display higher(^(87)Sr/^(86)Sr)i,Nb/Th,and lowerε_(Nd)(t),Zr/Nb values than those of the Late Devonian basalts,implying progressively decreased enrichment components in the magma source processes.Such evolution trend reflects a continuous lithospheric thinning event,supporting a progressive rifting setting of the Youjiang Basin along the southwestern margin of the Yangtze Block in Late Paleozoic.Combined with regional geological background,the Youjiang Basin is viewed as a continental rift basin related to the opening of the Paleo-Tethys Ocean in Late Devonian and became a passive continental margin basin in Carboniferous.The Paleo-Tethys branch ocean probably extended further to the southern Youjiang Basin,likely corresponding to the Song Ma suture zone.

关 键 词：BASALTS Late Paleozoic Paleo-Tethys ocean Youjiang Basin geochemistry 

分 类 号：P542[天文地球—构造地质学] P588.145[天文地球—地质学]