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

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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.