Paper No. 21
Presentation Time: 8:00 AM-5:00 PM
MICROBIALITES AS POST-PERMIAN EXTINCTION DISASTER FORMS: DETERMINING BIOGENICITY IN THE EARLY TRIASSIC DINWOODY FORMATION OF THE WESTERN UNITED STATES
Establishing standardized criteria from microbialite identification and classification is problematic and as of yet lacks scientific consensus. A highly diverse presence in the fossil record since the Archean, susceptibility to diagenesis, equivocal similarities to abiogenic structures, and the sheer volume of organisms and processes that can create them (many lacking modern analogs), all pose great uncertainties in interpreting them. Following the end-Permian extinction, microbialites propagated to dominate shallow marine environments as disaster formations in the ecological void following the end-Permian extinction. Globally, they share similar traits that suggest ubiquitous paleoceanic conditions and aids in their interpretation. The Dinwoody Formation will be evaluated a disaster formation containing microbialites with limited macrofossils. Microbial, inorganic, and/or diagenetic intervals will be delineated as clearly as possible, with an emphasis on linking process to potential reservoir quality. Field work will establish the presence of stromatolitic/thrombolitic macrostructures and ensure that samples reflect formation heterogeneity. Samples will undergo x-ray diffraction, scanning electron microscopy, and optical microscopy to detect microfossils, microfabrics, and bulk mineralogy. The low-energy shallow ramp on which the Dinwoody was deposited is consistent with microbialite occurrences in the Early Triassic. The recent discovery of hydrocarbons in microbialite reservoirs off the coast of Brazil emphasizes the economic importance of understanding these deposits. Characterizing related groups of ancient microbialites will illuminate a standardized workflow that allows for their accurate classification and identification in terms of implications on reservoir quality.