摘要
为系统认识珠江口盆地白云凹陷超深水区层序界面识别和沉积环境演变,笔者采用白云凹陷已钻A1井晚渐新统珠海组—早中新统珠江组碳酸盐岩层段微量元素和常量元素数据开展综合分析,研究表明:①通过Pb、Zn、Rb、Al2O3、Fe2O3、Th/U比值等参数的变化特征识别了 SB24.80、SB23.03和SB21.00共3个三级层序界面;②利用Sr/Ba、V/Ni、Sr/Cu、Al2O3/MgO、MgO/CaO比值的变化证实样品段以干热气候、海平面相对上升的沉积环境为主;③通过V/Cr、Ni/Co、V/(V+Ni)等比值表明,A1井碳酸盐岩主要发育在氧化环境的古海洋水体中,水体较浅,晚期水位上升趋向于贫氧环境,直至"淹死"终止碳酸盐岩发育.
Abstract
To systematically understand the sequence boundary identification and sedimentary environment evolution in the ultra-deep water area of the Baiyun Sag,Pearl River Mouth Basin,the authors conducted a compre-hensive analysis using trace and major element data from the carbonate rock section of the Late Oligocene Zhuhai Formation to Early Miocene Zhujiang Formation of the drilled Well A1 in Baiyun Sag.The results show:①Three third-order sequence boundaries of SB24.80,SB23.03 and SB21.00 were identified through the variation charac-teristics of parameters such as concentrations of Pb,Zn,Rb,Al2O3,Fe2O3,and Th/U ratio.②Based on the var-iability of Sr/Ba,V/Ni,Sr/Cu,Al2O3/MgO,and MgO/CaO ratios,it is confirmed that the sample section deposi-ted mainly in a sedimentary environment characterized by arid climate and relative sea-level rise.③Ratios of V/Cr,Ni/Co,V/(V+Ni)suggest that the carbonate rocks in Well A1 are mainly developed in ancient marine wa-ter bodies of oxidizing environments,with shallow water bodies.In the later stage,the water level tended to rise to-wards hypoxic conditions,and the development of carbonate rocks was terminated by"drowning".
基金项目
中国海洋石油有限公司"十四五"重大科技项目(KJGG2022-010)
维普
万方数据