冀北-辽西地区洪水庄期海洋氧化还原环境的不均一性  

HETEROGENEITY OF MARINE REDOX ENVIRONMENT DURING THE SEDIMENTARY PERIOD OF HONGSHUIZHUANG FORMATION IN NORTHERN HEBEI-WESTERN LIAONING

作　　者：张涛[1,2,3] 李永飞 孙守亮[3] 宗文明[3] 孙求实[3] 石蕾[3] ZHANG Tao;LI Yong-fei;SUN Shou-liang;ZONG Wen-ming;SUN Qiu-shi;SHI Lei(Guangzhou Institute of Geochemistry,CAS,Guangzhou 510640,China;University of Chinese Academy of Sciences,Beijing 100049,China;Shenyang Center of China Geological Survey,Shenyang 110034,China)

机构地区：[1]中国科学院广州地球化学研究所,广东广州510640 [2]中国科学院大学,北京100049 [3]中国地质调查局沈阳地质调查中心,辽宁沈阳110034

出　　处：《地质与资源》2021年第3期257-264,共8页Geology and Resources

基　　金：中国地质调查局项目“冀北-辽西中新元古界油气地质调查”(编号DD20190098).

摘　　要：洪水庄组沉积时期的海洋氧化还原条件及其对有机质保存的影响目前仍有较大的争议.通过对辽西地区洪水庄组页岩的稀土和微量元素进行分析,探究了该时期海洋氧化还原条件.研究区稀土元素丰度较高,分布范围为167.57×10^(-6)~316.95×10^(-6).稀土元素分布具有典型的海水特征,轻稀土较为亏损而重稀土相对富集.Ce负异常较为明显,基本不具有Eu异常,Y/Ho比值较低.微量元素(V、Cr、Ni、Co、Th和U)及其比值基本分布在一个较宽的范围内,说明该时期海洋具有不均一氧化的特征.稀土和微量元素指标均指示该时期海洋部分氧化和部分还原的特征,且部分地区属于硫化环境.综合华北北部其他地区洪水庄组氧化还原指标表明,该时期的海洋含氧量在空间上具有明显的不均一性,还原性较强的环境基本处于TOC较高的区域,与该区域的高生产力和丰富的营养元素有较好的关联性.The marine redox conditions during the sedimentary period of Hongshuizhuang Formation and its effects on the preservation of organic matter are still controversial at present.Through analysis of trace elements and REEs in the shale of Hongshuizhuang Formation in western Liaoning,the paper studies the marine redox conditions during this period.The abundance of REEs in the study area is high(167.57×10^(-6)-316.95×10^(-6)),and the distribution has typical seawater features,characterized by depleted LREEs and enriched HREEs,obvious negative Ce anomaly,no Eu anomaly and low Y/Ho ratio.The contents of trace elements(V,Cr,Ni,Co,Th and U)are distributed in wide range,indicating that the ocean was under heterogeneous oxidation.Both the indexes of trace elements and REEs reveal the ocean was under partial oxidation and partial reduction condition,and some areas under sulfidic condition.Combined with the redox indexes of Hongshuizhuang Formation in other areas of North China,it is considered that the oxygen content of ocean then had obvious spatial heterogeneity,and the region with high TOC was basically in strongly reduced environment,which has a good correlation with high productivity and rich nutrient elements in the region.

关 键 词：中元古代 氧化还原条件 洪水庄组 微量元素 冀北-辽西 

分 类 号：P595[天文地球—地球化学] P534.3[天文地球—地质学]