256-3 A Revised Richmondian Sequence Stratigraphic Framework for Central and Southern Tennessee

Session: Life and Environments Through Time and Space: Multi-Record Approaches to Stratigraphic Paleobiology, Part I

Presenting Author:

Authors:

Abstract:

The  Richmondian strata (Late Ordovician, Katian) of central Tennessee were divided into two third order sequences in the 1990s. However, these strata have received little attention over the following decades and refinement of the stratigraphic framework is overdue. To refine the stratigraphic framework for the region, we extend the sequence stratigraphic framework of Brett et al. (2020) from the Jessamine Dome into Tennessee.

            Analysis of Richmondian strata in central Tennessee indicates that all five third order sequences (C4-C8) of the Brett et al. (2020) framework as well as many of the fourth order sequences, can be recognized in the Nashville Dome. Preliminary work in the Sequatchie Valley and Valley and Ridge province indicates that many of these sequences can be recognized in the Appalachian basin as well. In the Nashville Dome, all but one of the recognized sequences (C8) demonstrate clear regional truncation from north to south. The majority of the identified sequences consist of a compact shell rich, typically phosphatic transgressive systems tract and a somewhat thicker more siliciclastic rich highstand systems tract, with the lowstand and falling stage removed. However, the C5 sequence does locally preserve the falling stage systems tract. These sequences lack a distinct maximum flooding surface and instead have a maximum flooding zone above the more prominent maximum starvation surface (MSS). Maximum starvation surfaces are commonly iron stained, coated in phosphate, and contain rip up clasts. The iron and phosphate which are concentrated in TSTs, and particularly at MSSs, were perhaps brought onto the platform via upwelling of nutrient rich dysoxic waters from the remnant Sebree trough to the west during transgressions.

Refining the Richmondian sequence stratigraphic framework for Tennessee will provide an improved temporal framework for studies of paleoecology, evolutionary change, far field tectonics, and mineral resource distribution. To this end, we extend the high resolution Richmondian sequence stratigraphic framework of Brett et al. (2020), developed for the Jessamine Dome, into the Nashville Dome and Appalachian Basin. The correlation of sequences from the Nashville platform northward into the Jessamine Dome and eastward into the foreland basin strongly supports an allocyclic origin and demonstrates an intimate link between climatic change, sea level fluctuations, and biotic events.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-6826

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