Comparative Diagenetic Analysis of Cambrian and Ordovician Sequences: Understanding Controls on the Pathway of Diagenesis Within Sequence-Stratigraphic Framework

研究了田纳西州东部两个大型层序的成岩作用：1)在中晚寒武世文石/高镁方解石促进作用时期沉积在斜坡环境中，2)在中奥陶世低镁方解石促进作用时期沉积在边缘台地上。对成岩历史与层序地层格架之间关系的理解将通过以下方式得到发展：1)进一步比较两个层序(例如；(2)对一个或另一个层序的独特岩性进行成岩研究(例如：寒武纪潮下“平卵石”砾岩)，以及3)通过测量两个层序的剖面分析成岩历史。薄片岩石学（偏振光和阴极发光），结合分析，以及微样品（0.3-0.6 mg）的成岩相和其他岩石成分的同位素分析将用于研究的各个部分。地球化学数据将用于模拟化学成分的传质，以帮助理解成岩过程中的流体流动。长期目标是建立一个与古环境和层序地层格架相媲美的成岩格架（地层+成岩过程+时间），并确定大尺度层序的成岩历史如何随环境和地质时代的不同而不同。

Diagenesis will be examined for two large scale sequences in eastern Tennessee: 1) one deposited in a ramp setting during a time of aragonite/high-magnesian-calcite facilitation in the Middle to Late Cambrian, and 2) one deposited on a rimmed platform during a time of low-magnesian calcite facilitation in Middle Ordovician. An understanding of the relationship between diagenetic history and sequence-stratigraphic framework will be developed by: 1) further comparison of similar lithologies occurring in both sequences (eg. oolite), 2) diagenetic studies of lithologies unique to one or the other sequence (eg. subtidal "flat-pebble" conglomerates of the Cambrian), and 3) analyses of diagenetic history through measured sections of both sequences. Thin-section petrography (polarized light and cathodoluminescent), coupled with analyses, as well as isotopic analysis of microsamples (0.3-0.6 mg) of diagenetic phases and other rock components will be used in all parts of the research. The geochemical data will be used to model mass transfer of chemical components to aid in understanding fluid flow during diagenesis. The long-term objective is to establish a diagenetic framework (stratigraphy + diagenetic processes + time) comparable in detail to the paleoenvironmental and sequence-stratigraphic framework previously developed, and to determine how the diagenetic history of large scale sequences differ depending on setting and geologic age.