Role of carbonaceous matter for redox systems in sediments and its geoscientific significance for diagenesis

本研究的目的是阐明碳质物质在沉积物中孔隙水的氧化还原电位（氧化还原电位）中的作用，以进行初始沉积和岩化。在与氧化锰有关的泥炭沼泽、洪水面、三角洲表面、珊瑚礁、石灰岩洞穴和温泉等选定的领域中，测量了沉积物中孔隙水的氧化还原、pH和电导率等水化学特性。采用透射光、反射光、x射线衍射仪、CN仪和CHN分析仪测定各寄主沉积物中的有机碳和无机碳。泥炭沼泽环境样品的氧化还原范围为10 ~ l2mV，洪水面和三角洲环境样品的氧化还原范围为120 ~ 210mV，珊瑚礁环境样品的氧化还原范围为97 ~ 118mV，石灰岩洞穴环境样品的氧化还原范围为290 ~ 334mV，温泉环境样品的氧化还原范围为150 ~ 314mV。泥炭沉积物的总碳含量最高可达86wt%，洪泛面和三角洲沉积物最高可达10wt%，珊瑚礁沉积物最高可达10wt%，石灰岩洞穴沉积物最高可达45wt%，温泉沉积物最高可达0.0wt%。一般观察到，碳质物质强烈影响沉积物的氧化还原系统，但石灰岩洞穴样品除外。在某些沉积环境中有机碳含量与无机碳含量呈反比，表明有机碳向无机碳转化。本研究已经确定了沉积环境中氧化还原与碳含量之间的关系，根据年代学或古生物学证据，持续时间对地球化学反应的影响需要进一步详细研究。

The purpose of this study is to elucidate the role of carbonaceous matter for oxidation-reduction potential (redox) of pore water in sediments for initial deposition and lithification.Water chemistry such as redox, pH and electrical conductivity of pore water in sediments was measured in the selected fields of peat swamps, flood planes, delta surfaces, coral reefs, limestone caves and hot springs associated with manganese oxide. The organic and inorganic carbon in each host sediment was determined by using transmitted and reflected light, X-ray diffractometer, CN corder and CHN analyzer.Redox ranges of 10 to l2mV were obtained for samples from peat swamp environments, 120 to 210mV for flood plane and delta, 97 to 118mV for coral reef, 290 to 334mV for limestone cave and 150 to 314mV for hot spring environments. Total carbon content ranges up to 86wt% for peat sediments, up to 10wt% for flood plane and delta sediments, up to 10wt% for coral reef sediments, up to 45wt% for limestone cave sediments, and 0.0wt% for hot spring sediments were recorded. It is generally observed that carbonaceous matter strongly affects redox systems of sediments except for samples fromlimestone caves. The content of organic carbon in some sedimentary environments appears to be inversely proportional to that of inorganic carbon, which suggests transformation of organic carbon to inorganic carbon.A relationship between redox and carbon content from selected sedimentary environments has been identified in this study and the effect of duration for geochemical reactions on the basis of geochronological or paleontological evidence requires further detailed study.