珠三坳陷文昌B凹陷古近系文昌组——恩平组古气候特征  

Paleoclimate characteristics of the Paleogene Wenchang-Enping Formation in Wenchang B Sag,Zhusan Depression

作　　者：马大钧 程斌[1] 付大巍 陈丽君 孟祥雨[1] 刘华[1] MA Dajun;CHENG Bin;FU Dawei;CHEN Lijun;MENG Xiangyu;LIU Hua(National Key Laboratory of Deep Oil and Gas,China University of Petroleum(East China),Qingdao 266580,Shandong,China;Zhanjiang Branch of China National Offshore Oil Corporation Ltd.,Zhanjiang 266510,Guangdong,China)

机构地区：[1]中国石油大学(华东)深层油气全国重点实验室,山东青岛266580 [2]中海石油(中国)有限公司湛江分公司,广东湛江266510

出　　处：《矿产勘查》2024年第6期946-955,共10页Mineral Exploration

基　　金：山东省自然科学基金(ZR2023MD107)资助。

摘　　要：古气候对有机质的生产和保存具有重要的作用,对烃源岩的发育至关重要,而温暖湿润的古气候条件通常被认为有利于优质烃源岩的形成。古近系文昌组及恩平组是珠三坳陷文昌B凹陷内最重要的烃源岩发育层段,恢复其沉积时期的古气候对凹陷内烃源岩优选有着至关重要的作用。本文选取文昌B凹陷WB-1、WB-2井泥、页岩样品,通过分析孢粉组合与主微量元素数据以得到沉积时期的古气候特征。孢粉组合特征表明凹陷内文昌组—恩平组烃源岩沉积时期气候整体为热—亚热带,湿润—半湿润;主微量元素证据中,古气候敏感性元素Sr/Cu及CIA指标进一步证实了这一时期气候温暖湿润的特性,特别是Mn/Mg及Rb/Sr比值强调了文二段沉积时期气候条件最为温暖湿润。因此,文二段沉积时期被认为是文昌B凹陷优质烃源岩发展的最佳时期。Paleoclimate plays an important role in the production and preservation of organic matter and is crucial for the development of source rocks,while warm and humid paleoclimate conditions are generally considered to be conducive to the formation of high-quality source rocks.The Paleogene E2w and E2e are the most important source rock development intervals in Wenchang B Sag,Zhusan Depression,and the restoration of paleoclimate during their sedimentary period plays a crucial role in the selection of source rocks in the sag.In this paper,the paleoclimate characteristics of the sedimentary period are obtained by analyzing the palynological assemblage and the data of main and trace elements from well WB-1 and WB-2 mud and shale samples from Wenchang B sag.The characteristics of palynological assemblages indicate that the climate of source rocks from E2w-E2e formation in the depression was tropical-subtropical and semi-humid.Among the main trace elements,the paleoclimate sensitive elements Sr/Cu and CIA further confirmed the characteristics of warm and humid climate in this period.In particular,the Mn/Mg and Rb/Sr ratios emphasized that the climate conditions in the deposition period of the second member of the E2w2 were the most warm and humid.Therefore,the deposition period of the second member of the E2w2 is considered to be the best period for the development of high-quality source rocks in Wenchang B Sag.

关 键 词：珠三坳陷 文昌B凹陷 古近纪 古气候 优质烃源岩 

分 类 号：P533[天文地球—古生物学与地层学]