108-8 Salvage sedimentology and petrography across the K-Pg boundary at ephemeral exposures of the Owl Creek and Clayton formations associated with highway construction in northern Mississippi, USA
Session: The Cretaceous-Paleogene (K-Pg) Boundary Interval: From Large-Scale Geological Events to Mass Extinction Mechanisms (Posters)
Poster Booth No.: 212
Presenting Author:
Brian PlattAuthors:
Platt, Brian F.1, Retrum, Julie B.2, Pizarro, Maxwell G.3(1) Geology and Geological Engineering, University of Mississippi, University, MS, USA, (2) Geology and Geological Engineering, University of Mississippi, University, MS, USA, (3) Geology and Geological Engineering, University of Mississippi, University, MS, USA,
Abstract:
The K-Pg boundary has received much study along the eastern arm of the Mississippi Embayment, where the structural expression of associated strata is well characterized. The highly erosive nature of the strata and the humid subtropical climate in the region, however, result in high weathering rates, very limited exposures, and few opportunities to study the interval. An ongoing state-supported construction project to widen the north-south oriented Mississippi (MS) State Highway 15 in Union and Tippah counties, MS, promises to expose much of the K-Pg boundary nearly along strike. This will provide a rare opportunity to investigate laterally extensive sedimentological and paleontological patterns throughout the lifetime of the work. Preliminary fieldwork involved measuring stratigraphic sections and collecting samples spanning the boundary at sites in southernmost Union County. There, the Owl Creek is fossiliferous, glauconitic muddy micrite to micritic sandstone and the Clayton Formation is sparry calcite-cemented fine-medium sand. Both units contain high opacity, spherical, coated grains, but these are much more common in the Clayton. The origin of these coasted grains is currently under investigation and planned x-ray diffraction will confirm their mineralogical composition to help interpret their origin, which does not appear to be consistent with a typical carbonate ooid shoal. The Clayton Formation contains sparry calcite-filled pores and pores surrounded by high sphericity, thin, clay walls, which we interpret as altered glass spherules associated with the Chicxulub impact. Some of these spherules are abraded, suggesting reworking, but additional research is needed to determine whether basal Clayton strata represent a tsunami deposit, seismically induced mass movements, or reworked material deposited upon a disconformable surface. The preliminary sites are no longer accessible because grading there is complete.
Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025
doi: 10.1130/abs/2025AM-11213
© Copyright 2025 The Geological Society of America (GSA), all rights reserved.
Salvage sedimentology and petrography across the K-Pg boundary at ephemeral exposures of the Owl Creek and Clayton formations associated with highway construction in northern Mississippi, USA
Category
Topical Sessions
Description
Session Format: Poster
Presentation Date: 10/20/2025
Presentation Room: HBGCC, Hall 1
Poster Booth No.: 212
Author Availability: 9:00–11:00 a.m.
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