141 New Advances in Geobiology
This session will focus on new research at the intersection between geologic and biologic processes with special emphasis on novel materials and methods, new field sites, and advances at the intersections of scientific fields.
Monday, 20 October 2025
1:30 PM - 5:30 PM
HBGCC, 305
High-Resolution Event Stratigraphy as a Tool for Studying Evolution: An Example from the Upper Cretaceous of the Mississippi Embayment
Paper number: 141-14
Program: Technical Sessions
Time: 5:00 PM – 5:15 PM
Authors
Abstract
High-resolution event stratigraphy combines data such as event beds and the first and last occurrences of taxa from multiple measured sections or wells to construct a single composite section. This ordinal composite provides a framework for examining the relationship between basin stratigraphy and the evolutionary patterns of their faunal constituents. In this study, data from 108 measured sections, three pseudosections, eight discrete events, 268 taxa of ostracods and planktonic foraminifera, and 353 samples from Santonian-Maastrichtian deposits on the eastern flank of the Mississippi Embayment (USA) into a single event composite using the heuristic software CONOP (Constrained Optimization). Two preparatory strategies were used prior to running the analyses: the construction of composite reference sections and integration of sequence boundaries. These methods yielded 544 events over a ∼20-million-year interval, averaging of one event approximately every 36,764 years. Diachroneity of the lithostratigraphic units also provides insight into the sluggishness of relative sea level change during the Late Cretaceous.
Patterns in ostracod diversity, evolutionary appearances, and extinction rates reveal three community stasis intervals, each separated by periods of elevated evolutionary turnover: the Lower Campanian, the Upper Campanian, and the uppermost Campanian-Maastrichtian. In the older two turnover intervals, spikes in evolutionary appearances preceded spikes in extinctions, resulting in temporary peaks in diversity followed by subsequent declines. Ostracod diversity reaches a maximum of more than 90 species during the mid-Campanian, coinciding with the maximum flooding surface of the deepest Cretaceous sequence in the region. No Cretaceous ostracod species survived the Cretaceous-Paleogene (K-Pg) boundary event.
Geological Society of America Abstracts with Programs. Vol. 57, No. 6
doi: 10.1130/abs/2025AM-414501
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