黄河口凹陷南斜坡古近系沙一段古气候、物源及源区构造背景  

Paleoclimate,provenance,and tectonic setting of the First Member of the Paleogene Shahejie Formation in the southern slope of Huanghekou Sag

作　　者：王萍 王飞龙 陈容涛 WANG Ping;WANG Feilong;CHEN Rongtao(CNOOC Experimental Center,CNOOC EnerTech-Drilling&Production Co.,Tianjin 300452,China;Tianjin Branch of CNOOC(China)Ltd.,Tianjin 300452,China)

机构地区：[1]中海油能源发展股份有限公司工程技术分公司中海油实验中心,天津300452 [2]中海石油(中国)有限公司天津分公司,天津300452

出　　处：《海洋地质前沿》2023年第11期63-75,共13页Marine Geology Frontiers

基　　金：中海油“十三五”油气资源评价项目(yxky-2018-kt-01)。

摘　　要：碎屑沉积岩的主微量元素记录了丰富的地球化学信息,可用于古气候、物源及构造背景的恢复。通过对黄河口凹陷南斜坡古近系沙河街组一段(沙一段,E_(1)s^(1))碎屑沉积岩元素地球化学分析,探讨了沙一段沉积时期古气候、物源及构造背景。Th/Sc-Zr/Sc图解和成分变异指数(ICV)表明,研究区沙一段物源为母岩风化后的首次沉积,成分成熟度较高;校正后的化学蚀变指数(CIA_(corr))和钾长石蚀变指数(PIA)表明沙一段物源经历了中等程度的风化作用,沙一段沉积时期气候温暖湿润;主、微量和稀土元素显示,沙一段物源主要表现为上地壳来源长英质火成岩的特征,具有明显的负Eu异常,主要来源于前寒武纪花岗岩类岩石和少量中基性混合物源;物源区具有活动大陆边缘和大陆岛弧的构造背景,较为复杂的构造背景与西太平洋板块向东亚大陆俯冲有关。The major and trace elements in clastic sedimentary rocks record abundant geochemical information,and can be used to reconstruct paleoclimate,provenance,and tectonic setting.Geochemical analysis of inorganic element in clastic sedimentary rocks of the first member of the Paleogene Shahejie Formation(E_(1)s^(1))in the southern slope of Huanghekou Sag was conducted,and the paleoclimate,provenance and tectonic setting of the Es^(1) were discussed.Th/Sc-Zr/Sc diagram and index of compositional variability(ICV)indicate that the source of the Es^(1) in the study area was the first deposition unit after weathering of the parent rocks,and the compositional maturity was relatively high.The corrected chemical index of alteration(CIAcorr)and plagioclase index of alteration(PIA)indicate that the source of the Es^(1) underwent moderate weathering,and the sedimentary period was warm and humid paleoclimatic conditions.Major,trace,and rare earth elements show that the provenance of Es^(1) is characterized by upper crust derived felsic igneous rocks,featuring obvious negative Eu anomaly,and the materials of provenance was mainly derived from Precambrian granitoids and some intermediate-basic mixture sources.The tectonic background of the provenance area was active continental margin and continental island arc.The complex tectonic background was related to the subduction of the Western Pacific plate to the East Asian continent.

关 键 词：物源 古气候 构造背景 沙一段 黄河口凹陷 

分 类 号：P736[天文地球—海洋地质]