108 The Cretaceous-Paleogene (K-Pg) Boundary Interval: From Large-Scale Geological Events to Mass Extinction Mechanisms (Posters)

The Cretaceous-Paleogene boundary interval witnessed extreme geological events: the Chicxulub impact and Deccan Traps volcanism, and a biological catastrophe. New proxy-records, coupled with numerical modelling, unravel the mechanisms driving the environmental change and mass extinction.

Monday, 20 October 2025
8:00 AM - 5:30 PM
HBGCC, Hall 1

Sedimentological and Paleontological Analysis of a New Cretaceous- Paleogene (K-Pg) Section Near Cotton Plant, Union County, Mississippi, USA.

Paper number: 108-3
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

One of the most continuous sections of K-Pg boundary sequence is exposed along a creek near Cotton Plant, Union county Mississippi. It represents one of the most fossiliferous K-Pg sequences in the Gulf Coastal Plain including abundant Eubaculites carinatus, E. latecarinaus, Discoscaphites iris and less common D. minardi and D. spheroidalis. The lower 1.6 m of the sequence is represented by the marly Owl Creek Formation where ammonites are extremely abundant as well as bivalves and gastropods. This is overlain by a sharp contact with the basal Clayton Formation showing evidence of soft sediment deformation. At the base is a 10cm – 20cm coarse sand with abundant impact spherules (these range in size from .5mm to 2mm) and reworked Cretaceous fossils including Eubaculites, Scaphites, Crassetella and Turritelids. Overlying this is a massive sand 40cm – 60cm thick with occasional laminations present including possible hummocky cross laminations and sparse fossils and impact spherules. There are burrows sporadically occurring in the top 30cm of this unit. The next unit is defined by abundant thin beds to laminations of lignitic material averaging 10 -15cm in thickness with some variability in places.  Above this is a 30cm heavily bioturbated fine quartz rich sand with broken oyster shell material, with increasing abundance at the top of the unit. The sequence is topped by an undulating unconformable contact with a shell hash unit comprised of small oysters, mostly Ostrea vomer. The units in the sequence can help us interpret the events before the Chicxulub Impact ( abundant ammonites, high biodiversity), evidence of the impact (impact spherules, high energy event such a tsunami including direct evidence of backwash from abundant lignite), to post impact recovery community (lower biodiversity ecosystem dominated by small oysters).

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

doi: 10.1130/abs/2025AM-414921

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