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

为阐明含碳物质对沉积物孔隙水氧化还原电位的影响，在泥炭沼泽、洪水面、三角洲表面、珊瑚礁、石灰岩洞穴和与氧化锰有关的温泉中测定了沉积物孔隙水的氧化还原电位、pH值和电导率等水化学参数。用透射光、反射光、X射线衍射仪、CN记录仪和CHN分析仪测定了各主体沉积物中的有机碳和无机碳，得到泥炭沼泽环境样品的氧化还原范围为10 ~ 12 mV，洪泛面和三角洲为120 ~ 210 mV，珊瑚礁为97 ~ 118 mV，溶洞环境为290 ~ 334 mV，温泉环境为150 ~ 314 mV。泥炭沉积物的总碳含量高达86wt%，洪泛面和三角洲沉积物高达10wt%，珊瑚礁沉积物高达10wt%，石灰岩洞穴沉积物高达45wt%，温泉沉积物为0.0wt%。除石灰岩洞穴样品外，沉积物中的碳质物质对氧化还原体系有强烈的影响。在某些沉积环境中，有机碳含量与无机碳含量成反比，表明有机碳向无机碳转化，氧化还原与碳含量之间存在一定的关系，而地球化学反应持续时间的影响还有待于进一步研究。

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.