局限环境下水体深度对有机质富集的控制作用  

The control of water depth on organic matter enrichment in confined environment

作　　者：毛小平[1,2] 陈修蓉 李书现 杨帆 李振[1] 李学慧 杨岳兴 MAO Xiaoping;CHEN Xiurong;LI Shuxian;YANG Fan;LI Zhen;LI Xuehui;YANG Yuexing(School of Energy and Resources,China University of Geosciences,Beijing 100083,China;State Energy Key Laboratory for Carbonate Oil and Gas,Beijing 102206,China;Reception Center of Tsinghua University,Beijing 100084)

机构地区：[1]中国地质大学(北京)能源学院,北京100083 [2]国家能源碳酸盐岩油气重点实验室,北京102206 [3]清华大学接待中心,北京100084

出　　处：《地质学报》2025年第4期1353-1368,共16页Acta Geologica Sinica

基　　金：国家能源碳酸盐岩油气重点实验室开放基金(编号33550000-24-ZC0613-0105)和贵州省战略矿产智慧勘查重点实验室联合资助的成果。

摘　　要：一般提到富有机质页岩的发育,就会关联到较深水缺氧环境,认为盆地沉积沉降中心深湖—半深湖水体较深处为缺氧还原环境,更易发育优质烃源岩。然而,现代水体中的有机质富集特征与这一观点恰恰相反,因此有必要深入剖析二者的关系。为此,本文利用环境学和生态学中关于水体溶解氧分布及现代湖泊表层沉积物中有机质含量等信息,研究了局限环境下水体不同深度有机质的富集特征。研究结果表明,水体溶解氧浓度随着水深的增加而增加;湖泊底部和海底在多数情况下为富氧环境;较深水体的初级生产力较低,不一定是低能环境和缺氧环境,这不利于有机质的保存;而潟湖、海湾及湖湾等相对封闭的局限环境可作为较好的有机质、矿物质和火山灰等的聚集场所。本文认为在面积较小的封闭—半封闭水体中,深度越浅越有利于有机质的富集;外源有机质的贡献不可忽视;开阔水体如深水陆棚、面积较大的深湖—半深湖等环境不具备发育优质烃源岩的条件。The prevailing paradigm in organic-rich shale development posits a strong association with deep anoxic environments.This view suggests that the deeper parts of deep-to-semi-deep lakes,located in the basin's sedimentary subsidence centers,provide the anoxic reducing conditions conducive to the formation of highquality source rocks.However,observations of organic matter enrichment in modern water bodies challenge this established notion,underscoring the need for a comprehensive examination of the relationship between water depth and organic matter accumulation.To address this,the present study integrates data on dissolved oxygen distribution in water bodies and organic matter content in surface sediments of modern lakes,drawing from environmental and ecological sciences,to investigate the enrichment characteristics of organic matter at different depths in enclosed water bodies.The results demonstrate that dissolved oxygen concentrations in water bodies increase with depth,indicating that the bottom layers of lakes and seas are,in most cases,oxygen-rich environments.Deeper water bodies exhibit lower primary productivity and are not necessarily characterized by low-energy or anoxic conditions,which are less conducive to the preservation of organic matter.In contrast,relatively enclosed environments,such as lagoons,bays,and lake bays,serve as more effective depositional settings for the accumulation of organic matter,minerals,volcanic ash,and other materials.This study concludes that in smaller enclosed to semi-enclosed water bodies,shallower depths are more favorable for the enrichment of organic matter.Furthermore,the contribution of exogenous organic matter cannot be ignored,as it plays a significant role in the overall enrichment process.Conversely,open water bodies,such as deep continental shelves and larger deep-to-semi-deep lakes,lack the necessary conditions for the development of high-quality source rocks.

关 键 词：溶解氧 页岩 氧化还原条件 大洋缺氧事件 沉积环境 

分 类 号：P618.13[天文地球—矿床学]