POWRE: Carbon-13 Heterogeneity in Devonian-Mississippian Marine Shales: Integration of Density-Gradient Centrifugation (DGC) and Organic Petrography into Isotopic Studies

0074840 Rimmer有机岩相学可以识别和量化沉积岩中的有机组分（显微组分），因此可以指示盆地中陆地和海洋输入的不同水平和类型。 了解泥盆纪和密西西比纪有机组分的碳同位素组成是了解肯塔基州中部富含有机物的页岩单元的旋回性的关键，这些页岩单元显示出dm、一到两米和更大尺度的变化。 在将C-13值的变化归因于全球CO2变化、氧化还原条件变化或有机生产力水平变化之前，必须评估海洋和陆地有机输入的不同数量和类型的影响。 这项研究将解决这些问题，因为它们涉及到上泥盆统/下密西西比有机丰富的页岩阿巴拉契亚盆地。 这些岩石由II型干酪根组成，含有海洋和陆地组分（显微组分）的混合物，而不是纯粹的海洋有机物质。 具体而言，碳同位素分析将与这些页岩的富碳和贫碳间隔的干酪根浓缩物的全岩和密度梯度部分的岩相分析相结合。 这项工作的关键是密度梯度离心分离干酪根成其组分显微组分的能力。 这些页岩中的干酪根至少含有两种海相组分（藻质组和沥青组）和两种陆源组分（镜质组和惰质组）。 PI将确定存在于这些岩石中的显微组分类型及其各自的碳同位素组成的数量和变化。 这些数据将用于进一步阐明在这些沉积物中观察到的周期性变化。 这项工作也有重要的影响，解释在古生代的有机质的稳定碳同位素组成的长期变化，和推论，可能是相对于大气中的CO2。 此时来自POWRE计划的资金将允许该研究者重振其研究计划，并在延长的管理时间（7年）后建立/重新建立研究合作。 它也代表了研究人员研究到一个新领域（稳定碳同位素）的自然进展和增长。 该研究也将在稳定碳同位素研究领域做出重要贡献。

0074840RimmerOrganic petrography allows the identification and quantification of organic components (macerals) in sedimentary rocks, and as such can indicate varying levels and types of terrestrial and marine inputs to basins. Understanding the carbon isotopic composition of Devonian-and Mississippian-age organic components is key to understanding cyclicity in the organic-rich shales units of central Kentucky that show variations on the order of dm, one-to-two-meter, and larger scales. Before arguments can be made to attribute variations in delta C-13 values to global changes in CO2, to changing redox conditions, or to variations in organic productivity levels, the impact of varying amounts and types of marine and terrestrial organic input must be evaluated. The research will address these issues as they relate to Upper Devonian/Lower Mississippian organic-rich shales of the Appalachian Basin. Consisting of Type II kerogen, these rocks contain a mixture of marine and terrestrial components (macerals), rather than purely marine organic matter. Specifically, carbon isotope analysis will be combined with petrographic analysis of both whole-rock and density-gradient fractions of kerogen concentrates for carbon-rich and carbon-poor intervals of these shales. Key to this work is the ability of density-gradient centrifugation to segregate kerogen into its component macerals. Kerogen in these shales contains at least two marine components (alginite and bituminite) and two terrestrial components (vitrinite and inertinite). The PI will identify amounts and variations in the type of macerals that exist in these rocks and their respective carbon isotopic compositions. Such data will be used to further elucidate cyclical changes observed in these sediments. This work also has important implications regarding the interpretation of long-term variations in the stable carbon isotope composition of organic matter in the Paleozoic, and inferences that may be made relative to CO2 in the atmosphere. Funding at this time from the POWRE program will allow this investigator to reinvigorate her research program, and establish/re-establish research collaborations after an extended time in administration (7 years). It also represents a natural progression and growth of the investigator's research into a new area (that of stable carbon isotopes). The research will also make an important contribution in the field of stable carbon isotope research.