东海盆地长江坳陷美人峰组烃源岩沉积环境与生烃潜力评价  

Sedimentary Environment and Hydrocarbon Generation Potential of Source Rocks from the Meirenfeng Formation in the Changjiang Depression,East China Sea Basin

作　　者：袁灵聪 朱晓军[1,2] 蔡进功 钟锴[1,2] YUAN LingCong;ZHU XiaoJun;CAI JinGong;ZHONG Kai(State Key Laboratory of Marine Geology,Tongji University,Shanghai 200092,China;Research Center for Marine Resources,Tongji University,Shanghai 200092,China)

机构地区：[1]同济大学海洋地质国家重点实验室,上海200092 [2]同济大学海洋资源研究中心,上海200092

出　　处：《沉积学报》2021年第2期506-514,共9页Acta Sedimentologica Sinica

基　　金：国家科技重大专项(2016ZX05027-001-008)。

摘　　要：利用东海盆地长江坳陷古新统美人峰组烃源岩的元素、热解、干酪根δ^(13)C、镜质体反射率、岩石薄片、X射线衍射等资料,对长江坳陷美人峰组不同层段烃源岩进行沉积环境分析及生烃潜力评价。研究结果表明:美人峰组烃源岩的沉积环境整体表现为温暖潮湿的弱氧化淡水环境,古盐度和古气候是控制美人峰组烃源岩发育的主要环境因素。美人峰组第一段和第二段沉积时期,气候温暖潮湿,有大量陆源有机质输入,水体盐度相对较高,有机质保存条件较好,有机质丰度高,有机质类型以Ⅲ型为主,含少量II型,有机质已进入低成熟—成熟演化阶段,是美人峰组最具生烃潜力的层段;第三段和第四段沉积时期,气候相对干热,陆源碎屑及有机质输入少于第一段和第二段,水体盐度较低,不利于有机质保存,有机质丰度较低,有机质类型以Ⅲ型为主,有机质以低成熟演化阶段为主,生烃潜力不大;第五段和第六段沉积时期,气候恢复为温湿状态,有机质丰度较第三段和第四段高,有机质类型为Ⅲ型,但有机质热演化程度低,处于未熟状态,为无效烃源岩。随着埋深增加,美人峰组烃源岩的有机质成熟度变高,具有更大的生烃潜力。Trace element content,pyrolysis,kerogenδ^(13)C,vitrinite reflectance,thin-sections and X-ray diffraction images were examined to determine the sedimentary environment and hydrocarbon generation potential of source rocks in the different layers making up the Meirenfeng Formation in the Changjiang Depression,East China Sea Basin.These revealed a suboxic freshwater sedimentary environment in a warm,humid climate.Paleosalinity and paleoclimate were the main environmental factors in source rock development.During deposition of the first and second members,the climate was warm and humid.There was a large amount of terrestrial organic matter(OM)input and the salinity was relatively high,which has benefited OM preservation.The OM is highly abundant and is mainly typeⅢ,with a small amount of typeⅡmaturity is mainly in the low-mature to mature stage,indicating that these members have the greatest hydrocarbon generation potential.During deposition of the thirdand fourth members,the climate was relatively dry and hot and input of terrigenous minerals and OM was reduced,and the salinity was lower than for the firstand second members.The OM has low abundance and is mainly typeⅢ,with mainly low-maturity,suggesting a low hydrocarbon generation potential.Deposition of the fifth and sixth members saw the climate again become warm and humid.The OM is more abundant than in the thirdand fourth members,but is typeⅢand mainly at the immature stage,which indicates no exploration potential.The fact that the maturity of the Meirenfeng Formation source rocks was found to increase with greater burial depth suggests that the potential for hydrocarbon generation is better in the deeper rock.

关 键 词：烃源岩 沉积环境 生烃潜力 美人峰组 长江坳陷 

分 类 号：P618.13[天文地球—矿床学]