Late Jurassic Volcanism Deduced from Geochemical,Geochronological,and Sr-Nd-Hf Isotopic Composition Characteristics of the Nanyuan Formation,South China  

作　　者：WANG Dongsheng LI Jinwen SHE Hongquan WANG Kunming YANG Junzhi REN Chenghao 

机构地区：[1]MNR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences(CAGS),Beijing 100037,China [2]Forestry and Grassland Administration of Shanxi Province,Taiyuan 030021,China

出　　处：《Acta Geologica Sinica(English Edition)》2023年第2期449-468,共20页地质学报（英文版）

基　　金：supported by the Deep Resources Exploration and Mining Project(Grant No.2019YFC0605202);China Geological Survey Project(Grant Nos.DD20221684,DD20221795,DD20201173)。

摘　　要：The Nanyuan Formation contains information related to the Mesozoic tectonic transformation.In this study,three representative profiles were surveyed from the Nanyuan Formation,and multiple analyses were conducted.Zircon U-Pb dating yielded their ages as approximately 158–146 Ma.The volcanic rocks are enriched in Rb,Th,U,K,and Pb and depleted in Nb,Ta,P,and Ti,implying their affinity for I-type granites.TheεNd(t)values(-8.3 to-6.0),^(87)Sr/^(86)Sr)i values(0.7077–0.7094)of the volcanic rock,andεHf(t)values(-8.71 to 0.12)of the Mesozoic zircons suggest that the Nanyuan Formation magma originated in the lower crust with the involvement of depleted mantle materials.The parent rocks of the rhyolitic and dacitic volcanic rocks formed by partial melting of basement rocks in South China and the andesitic volcanic rocks were derived from partial melting of the metasomatites generated by slab-mantle interaction.The fractional crystallization also played an important role in later stage.Discrimination diagrams of the volcanic rocks indicated that they formed in a volcanic arc environment.Combined with previous data,the Nanyuan Formation recorded subduction of the Paleo-Pacific Plate before regional tectonic transformation.The compressive stress field endured until the end of the Late Jurassic.

关 键 词：Late Jurassic Nanyuan Formation volcanic rocks volcanic arc geochemistry PETROGENESIS Pinghe 

分 类 号：P534.52[天文地球—古生物学与地层学] P588.14[天文地球—地质学]