Geochemistry of the Paleocene Clastic Rocks in Lishui Sag, East China Sea Shelf Basin： Implications for Tectonic Background and Provenance

作     者：LI Deyong JIANG Xiaodian XU Fa LIU Jinshui HOU Guowei 

作者机构：College of Marine GeosciencesOcean University of ChinaQingdao 266100ShandongChina Key Lab of Submarine Geosciences and Prospecting TechniquesMinistry of EducationQingdao 266100ShandongChina Shanghai BranchChina National Offshore Oil Co.Ltd.Shanghai 200030China 

出 版 物：《Acta Geologica Sinica(English Edition)》 (地质学报（英文版）)

年 卷 期：2016年第90卷第1期

页      面：166-181页

核心收录：

学科分类：070704[理学-海洋地质] 0709[理学-地质学] 0819[工学-矿业工程] 07[理学] 0707[理学-海洋科学] 0818[工学-地质资源与地质工程] 0708[理学-地球物理学] 0816[工学-测绘科学与技术] 

基　　金：supported by the Fundamental Research Funds for the Central Universities of Ocean University of China(201413005) a China National Science and Technology Major Project(2011ZX05023003) Shanghai Branch,China National Offshore Oil Co.,Ltd.(CNOOC) 

主　　题：geochemistry Paleocene tectonic background provenance Lishui sag 

摘      要：The Lishui Sag, in the East China Sea Shelf Basin, is rich in hydrocarbons, with the major hydrocarbon-bearing layers being the Paleocene Mingyuefeng clastic rocks. Analysis of the implicit geologic background information of these Paleocene clastic rocks using petrological and geochemical methods has significant practical importance. These Paleocene sandstones are mainly lithic arenite, lithic arkose and greywacke, composed of K-feldspar, plagioclase, authigenic clays, silica and carbonates. As continental deposits, Yueguifeng clastic rocks have high aluminosilicate and mafic detritus contents, while the Lingfeng and Mingyuefeng Formations are rich in silica due to an oscillating coastal marine depositional environment. The major element contents of these Paleocene sandstones are low and have a concentrated distribution, indicating that the geochemical composition is non-epigenetic, transformed by sedimentary processes and diagenesis. The Yueguifeng detritus comprises recycled sediments, controlled by moderate weathering and erosion, while the Lingfeng and Mingyuefeng detritus is interpreted as primarily first-cycle materials due to low chemical weathering. In the Late Cretaceous to Early Paleocene, the Pacific Plate began subducting under the Eurasian Plate, causing an orogeny by plate collision and magma eruption due to the melting of subducted oceanic crust. This resulted in the dual tectonic settings of ＂active margin＂ and ＂continental island arc＂ in the East China Sea Shelf Basin. During the Late Paleocene, the Pacific Plate margin migrated eastward along with development of the Philippine Ocean Plate, and the tectonic setting of the Lishui Sag gradually turned into a passive continental margin. Detrital sources included both orogenic continental blocks and continental island arcs, and the parent rocks are primarily felsic volcanic rocks and granites.