High-Resolution Event Stratigraphy of Ostracods in the Ozan Formation of Texas and Arkansas
type: CreativeWork
description: This study focuses on the high-resolution event stratigraphic framework of the lower Campanian Ozan Formation in Northeast (NE) Texas and Southwest AR which is richly fossiliferous in ostracods. Little research has been published on the Ozan Formation and even less dealing with Ozan ostracods. Additionally, correlation of Upper Cretaceous units between Texas and AR is controversial due to the general lack of good exposures in both regions and extensive faulting in Northeast Texas despite similar depositional environment across the region. This study calibrates the ranges of ostracods and creates an event stratigraphic composite that is orders of magnitude higher in resolution than existing taxon range zones for the region. Information from the samples collected in this study and information from Ph.D. dissertations and M.Sc. theses were combined to create the most parsimonious correlation of the sections. A heuristic program, Constrained Optimization (CONOP), was used for correlation by creating an ordinal scale of all input events representing the optimized ranges of the taxa. Twenty-four samples were collected within the study region, totaling 134 events, from 64 species of ostracoda. The resulting composite plots within the expected published sequence, though the results presented here are at a much higher resolution than published taxon range zones due to the inclusion of all taxon events; the resolution achieved here was approximately 7500 years/event. The results from this analysis can be integrated into other stratigraphic analyses in the region to help constrain the sequence of events.
abstract: This study focuses on the high-resolution event stratigraphic framework of the lower Campanian Ozan Formation in Northeast (NE) Texas and Southwest AR which is richly fossiliferous in ostracods. Little research has been published on the Ozan Formation and even less dealing with Ozan ostracods. Additionally, correlation of Upper Cretaceous units between Texas and AR is controversial due to the general lack of good exposures in both regions and extensive faulting in Northeast Texas despite similar depositional environment across the region. This study calibrates the ranges of ostracods and creates an event stratigraphic composite that is orders of magnitude higher in resolution than existing taxon range zones for the region. Information from the samples collected in this study and information from Ph.D. dissertations and M.Sc. theses were combined to create the most parsimonious correlation of the sections. A heuristic program, Constrained Optimization (CONOP), was used for correlation by creating an ordinal scale of all input events representing the optimized ranges of the taxa. Twenty-four samples were collected within the study region, totaling 134 events, from 64 species of ostracoda. The resulting composite plots within the expected published sequence, though the results presented here are at a much higher resolution than published taxon range zones due to the inclusion of all taxon events; the resolution achieved here was approximately 7500 years/event. The results from this analysis can be integrated into other stratigraphic analyses in the region to help constrain the sequence of events.
author: John, Denali L
keywords: Cretaceous, ostracods, WIS, CONOP, Stratigraphy, Correlation, Geology, Paleontology
date published: 2025-08-01T07:00:00Z
date modified: 2026-07-24T05:45:47Z
provider: University of Southern Mississippi
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Southern Mississippi