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Detrital Zircon Geochronology of Basal Cambrian Arenites in Middle Tennessee: Implications for Grenvillian Sedimentation and Recycling in Eastern Midcontinental USA

Session: Advances and Applications in Geochronology for Interpreting Stratigraphic and Basin Records (Posters)

Presenting Author:

Krista Risner

Authors:

Risner, Marie¹, Clay, Dr. John Mitchell²

(1) Earth and Environmental Sciences, Austin Peay State University, Clarksville, Tennessee, USA, (2) Department of Life, Earth, and Environmental Sciences, West Texas A&M University, Canyon, Texas, USA,

Abstract:

Neoproterozoic-Cambrian rifting followed by Cambrian transgression formed the Great Unconformity in eastern Laurentia. This must have involved the recycling of sediment produced during the Grenville Orogeny. The goal of studying basal Cambrian sandstones is to determine whether the Cambrian transgression reworked Neoproterozoic Grenvillian sediment, or if new sediment was generated from underlying Precambrian basement. Crustal elements within the basement of the region include (1) the ~1.1 Ga East Continent Rift (ECR); (2) the ~0.98 Ga Grenville Frontal Thrust Fault that separates 1.4 Ga Granite-Rhyolite crust in the footwall from 1.3 – 1.0 Ga Grenvillian orogenic crust in the hanging wall; and (3) the Early Cambrian Rome Trough, a failed rift that overlies the ECR and Grenville Front. Recent interpretation of the basal Cambrian in KY determined that the sandstone is a product of erosion of the underlying basement: the Grenville and Granite-Rhyolite Provinces. The basal Cambrian between the Appalachians and US Midcontinent are available from sparse outcrops and rare drill cores. The Johnsonville Site Study Well (JSSW) drilled in Waverly, TN during the early 1990s purportedly recovered rock core that contains the basal Cambrian sandstone, which has yet to be observed in the Middle Tennessee subsurface. U-Pb detrital zircon geochronological analyses have been carried out on samples of this core to determine sedimentary provenance of the basal Cambrian sandstone in Middle Tennessee. The results of this study show that basal Cambrian sandstones in the Middle Tennessee region of the US Midcontinent consist, in part, of Granite-Rhyolite Province magmatic rocks that were reworked during late Grenvillian orogenesis, similar to findings in eastern Tennessee, central and eastern Kentucky, and southern Ohio.