Geochemical and Stable Isotopic Study of the Corg-S-Fe-Mn inAnoxic Paleoenvironments

碳、硫、铁的早期成岩再分配， 锰在贫氧至缺氧海洋沉积物中， 使用新的地球化学和稳定同位素数据研究了 中新世蒙特利组和白垩纪中期Greenhorn 阵 我们的目标是：1）解释相互关系- Corg-S-Fe-Mn体系中的沉积作用， 早期成岩条件; 2）重建通道 用于从溶解和固体无机硫中转移硫 沥青和干酪根中的有机硫化合物。 有机和无机硫物质将使用 一个逐步的程序，将产生七个硫馏分 （硫酸盐，元素，沥青，酸挥发性，二硫化物，重晶石， 和油母质）。 黄铁矿形成的深度和时间 硫与有机物的结合可以从 不同硫组分的同位素组成 与铁和锰的分布有关。 的 蒙特利和格林霍恩都含有夹层层状和 生物扰动岩相，使我们能够采样广泛的 一系列的古环境和早期成岩背景。 有机和无机硫数据与锰的整合 铁的数据将为解释古代 缺氧盆地。 地质单位 选择这项研究将允许比较沉积 现代和中新世海岸隆起和现代 海洋和白垩纪陆缘环境。

Early diagenetic repartitioning of carbon, sulfur, iron, and manganese in poorly oxygenated to anoxic marine deposits will be studied using new geochemical and stable isotopic data on the Miocene Monterey Formation and the mid-Cretaceous Greenhorn Formation. Our objectives will be 1) to interpret interrela- tionships in the Corg-S-Fe-Mn system in terms of depositional and early diagenetic conditions and 2) to reconstruct the pathways for transfer of sulfur from dissolved and solid inorganic-sulfur species to organic-sulfur compounds in bitumen and kerogen. Organic and inorganic sulfur species will be isolated using a step-wise procedure that will yield seven sulfur fractions (sulphate, elemental, bitumen, acid-volatile, disulfide, barite, and kerogen). Depth and timing of pyrite formation relative to incorporation of sulfur into organic matter will be inferred from the isotopic compositions of the various sulfur fractions in conjunction with the distribution of iron and manganese. The Monterey and Greenhorn both contain interbedded laminated and bioturbated lithofacies that will enable us to sample a wide range of paleoenvironmental and early diagenetic settings. Integration of organic and inorganic sulfur data with manganese and iron data will provide a new basis for interpreting ancient poorly oxygenated to anoxic basins. The geological units selected for this study will permit comparison of sedimentary strata in modern and Miocene coastal upwellings and in modern oceanic and Cretaceous epicontinental settings.