沉积历史对大陆坡甲烷水合物成藏的影响  

The influence of sedimentary history on the formation of methane hydrate reservoir at continental slopes

作　　者：郑子涵 曹运诚[2] 杨胜雄 陈多福[1,2] ZHENG Zihan;CAO Yuncheng;YANG Shengxiong;CHEN Duofu(State Key Laboratory of Isotope Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;Shanghai Engineering Research Center of Hadal Science and Technology,College of Marine Sciences,Shanghai Ocean University,Shanghai 201306,China;University of Chinese Academy of Sciences,Beijing 100049,China;Southern Marine Science and Engineering Guangdong Laboratory,Guangzhou 511458,Guangdong,China)

机构地区：[1]中国科学院广州地球化学研究所,同位素地球化学国家重点实验室,广东广州510640 [2]上海海洋大学海洋科学学院,上海深渊科学工程技术研究中心,上海201306 [3]中国科学院大学,北京100049 [4]南方海洋科学与工程广东省实验室,广东广州511458

出　　处：《地球化学》2022年第4期462-471,共10页Geochimica

基　　金：国家自然科学基金项目(41730528、41776050、91858208);中国地质调查项目(DD20190230);南方海洋科学与工程广东省实验室(广州)人才科研启动项目(GML2020GD0802)联合资助。

摘　　要：天然气水合物主要发育于大陆边缘陆坡区,该区快速变化的沉积速率会影响天然气水合物成藏。本文以水合物系统甲烷质量守恒为基础,建立沉积速率对甲烷水合物成藏控制的数值模型,分析美国东海岸布莱克海台ODP 164航次994站位沉积速率变化对水合物形成与分解过程的影响,探索水合物成藏的历史。研究结果显示:ODP994站位的甲烷水合物在高速沉积时期以分解为主,在低速沉积时期以生成为主,目前水合物藏的甲烷资源量为5.15×10^(4) mol/m^(2),计算的稳定带底界甲烷水合物饱和度为6%,该值与钻探岩心获得的沉积物孔隙水盐度异常确定的值一致。因此,大陆坡沉积速率是甲烷水合物饱和度及资源量的重要影响因素。Sedimentation and burial rate vary considerably at continental slopes, which could impact the formation of methane hydrate reservoirs. In this study, we established a methane hydrate accumulation model with variable sedimentation rates at continental slopes by considering the mass conservation of methane. We evaluated the effects of varied sedimentation rates on hydrate formation or decomposition at the hydrate system of Site 994 of the ODP Leg 164 at Blake Ridge. During hydrate system evolution, the accumulation of methane hydrate was dominant during low sedimentation rates, but the dissociation of methane hydrate dominated during high sedimentation rates. The methane hydrate resource reached 5.15×10^(4) mol/m^(2) and the hydrate saturation at the base of hydrate stability zone peaked at 6%, which is in good agreement with the estimations based on the drilling data.Therefore, the continental slopes where the sedimentation rate changes had a significant effect on methane hydrate saturation and resources.

关 键 词：沉积历史 甲烷水合物 水合物形成与分解 布莱克脊ODP 994站位 

分 类 号：P67[天文地球—海洋地质]