地质科学2025，Vol.60Issue(4)：975-990,16.DOI:10.12017/dzkx.2025.065
东海盆地丽水凹陷古元古代片麻岩的锆石U-Pb年代学、地球化学及其对古老基底属性的指示
Zircon U-Pb geochronology and geochemistry of the Paleoproterozoic gneisses from the Lishui Sag of East China Sea Basin:Indication of ancient basement attributes
摘要
Abstract
The East China Sea Basin is the largest Mesozoic-Cenozoic superimposed oil and gas-bearing basin in China's offshore areas.Its basement is considered to be an extension of the Precambrian basement of the eastern Cathaysia Block.In order to explore the tectonic evolution of the Paleoproterozoic basement in the East China Sea Basin,this study conducted systematic petrological,isotopic geochronological and geochemical analyses on the newly discovered biotite plagioclase gneisses in the Lishui Sag of the East China Sea Basin.The results of LA-ICP-MS zircon U-Pb dating indicate that its formation age is 1 864±6 Ma.It has proved the existence of a Paleoproterozoic magmatic event in the East China Sea Basin.Geochemical analysis shows that the metaluminous gneisses(SiO2=59.77％～63.40％,A/CNK=0.86～0.94)are enriched in large-ion lithophile elements(LILEs:Rb,Ba,K),depleted in high-field-strength elements(HFSEs:Nb,Ta,Ti),and exhibit elevated Sr/Y(17.99～32.58)and La/Yb(6.10～9.60)ratios.It has indicated that its protoliths were adakitic diorite derived from partial melting of a thickened lower crust under amphibolite-facies conditions.Petrological evidence reveals plastic deformation features including plagioclase cataclasis and biotite preferred orientation.Combined with regional correlations,it indicates magmatic consanguinity with 1.89～1.83 Ga Paleoproterozoic granites in the eastern Cathaysia Block.The study has shown that the basement of the Lishui Sag in the East China Sea Basin participated in the collision orogeny event of the Cathaysia Block during the Paleoproterozoic.It was formed under the tectonic background of thickened crust in the orogenic belt and confirmed the tectonic unity between the Cathaysia Block and the Lishui Sag in the East China Sea Basin during the Paleoproterozoic.关键词
锆石U-Pb年代学/片麻岩/前寒武纪基底/古元古代/东海盆地/华夏地块Key words
Zircon U-Pb chronology/Gneiss/Precambrian basement/Paleoproterozoic/East China Sea Basin/Cathaysia Block分类
天文与地球科学引用本文复制引用
程琦,刘彬,郭晋威,黄晓松,唐贤君,蔡昊龙,朱正平..东海盆地丽水凹陷古元古代片麻岩的锆石U-Pb年代学、地球化学及其对古老基底属性的指示[J].地质科学,2025,60(4):975-990,16.基金项目
国家自然科学基金项目(编号:42130309,41502050,42302226)和安徽省自然科学基金项目(编号:2208085MD96)资助 （编号:42130309,41502050,42302226）
