海洋地质前沿2025，Vol.41Issue(6)：14-24,11.DOI:10.16028/j.1009-2722.2024.110
上扬子西缘五峰组-龙马溪组下段黑色岩系地球化学特征及其沉积-构造意义
Geochemical characteristics of the black rock series in the Wufeng-Longmaxi Formations on the western margin of the Upper Yangze and the sedimentology and tectonic implications
摘要
Abstract
The black rock series of Wufeng Formation and Longmaxi Formation are widely deposited from Late Ordovician to Early Silurian in the western margin of the upper Yangtze region.However,systematic studies on their sedimentology and tectonic background are scarce.In-depth studies on the geochemistry of samples from Wufeng Formation and the lower part of Longmaxi Formation in the Jinkecun section of Junlian County,Sichuan Province were conducted.Results show that the average σ ΣREE of Wufeng Formation in the section is 145.37×10-6,and that of the lower part of Longmaxi Formation is 158.54×10-6.Both are characterized by the rel-ative enrichment of light rare earth elements and the loss of heavy rare earth elements.The enrichment of large-ion lithophile elements such as Rb,Th and U,and the loss of high-field strength elements such as Nb,Sr and Ti.Ce and Eu show weak negative anomalies.During the deposition period of Wufeng Formation,the water body first deepened and then shallowed,resulting in redox changes from hypoxic to anaerobic,and then to hypoxic condi-tion again.When it entered the deposition period of Longmaxi Formation,the climate quickly warmed up,and the water body deepened and turned into a hypoxic environment again.The sedimentary characteristics of first accel-erating and then slowing down from bottom to top and its relatively complex provenance of the Wufeng Forma-tion reflect that the Wufeng Stage of the Late Ordovician was in an island arc environment during the arc-contin-ent collision stage of the Yangtze Plate subduction and collision with Cathaysia Plate.It turned into a stable tec-tonic environment in the Longmaxi period.The single provenance also indicates that the Guangxi Movement in this area has ended in stages.关键词
上扬子西缘/五峰组/龙马溪组/地球化学/构造背景Key words
western margin of Upper Yangtze Region/Wufeng Formation/Longmaxi Formation/geochemistry/tectonic setting分类
地质学引用本文复制引用
王万能,庞占基,李金旺,李文辉,袁永盛,吴亮,张耀堂,李锁明,赵见波..上扬子西缘五峰组-龙马溪组下段黑色岩系地球化学特征及其沉积-构造意义[J].海洋地质前沿,2025,41(6):14-24,11.基金项目
中国地质调查局项目"滇中楚雄地区云龙镇等4幅1:50 000区域地质调查"(DD20220987) （DD20220987）
