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寒武纪早期及以前的地球海洋(>520 Ma;以下简称为“早期地球海洋”)具有广泛缺氧分层和有限氧化剂供应等特点,其化学特征可与现代海洋陆架区沉积物孔隙水类比.依据相似的地球化学原理和对于早期地球海洋化学形成机制的理解,本文提出早期地球海洋在陆架-斜坡浅水-中等水深区域在理想化条件下可能存在多个由不同氧化还原过程控制的动态化学分带,从近岸浅水到远洋深水依次发育:氧化带、NO3?-NO2?富集带、Mn2+-Fe2+富集带、硫化带、CH4富集带和深水Fe2+区.它们是大气自由氧对表层海水的氧化、化学跃变层之下反硝化作用、近岸区域锰铁氧化物还原作用、硫酸盐还原作用、产甲烷作用和深水热液Fe2+输入动态平衡后的结果.该化学分带模型细化了目前已有的古海洋水化学状态分类,对现有的古海洋“硫化楔”模型进行了扩展和补充,并较好解释了早期地球海洋不寻常的Mo-S-C同位素地球化学记录.该化学分带模型对未来早期地球海洋化学演化及元素生物地球化学循环研究具有指导意义.
The characteristics of the Early Cambrian and former Earth Seas (> 520 Ma; hereinafter referred to as “Early Earth Oceans”) with extensive anoxic delamination and limited oxidant supply can be compared with the sediment porosity of modern marine shelf areas Based on the similar geochemical principles and the understanding of the formation mechanism of early marine ocean chemistry, this paper proposes that there may be multiple under the idealized conditions for the early Earth oceans to be under the control of different redox processes in the shelf-slope shallow water-mid-water depth region Dynamic chemical zonation, followed by shallow water from the nearshore to the deep ocean in the following order: oxidation zone, NO3? -NO2? Enrichment zone, Mn2 + -Fe2 + enrichment zone, sulfide zone, CH4 enrichment zone and deep water Fe2 + Oxidation of surface seawater, denitrification below the chemical transition layer, manganese-iron oxide reduction in the inshore area, sulfate reduction, methane production and dynamic equilibrium of Fe2 + input to deep hydrothermal fluids. The model has refined the existing classification of paleoceanic water chemistry and expanded and supplemented the existing paleoceanic / wedged wedge model, and better explained the characteristics of the early Earth Oceans Unusual Mo-S-C Isotope Geochemical Records The chemical zoning model is instructive for the study of the early evolution of marine ocean chemistry and elemental biogeochemical cycles.