69-3 Post-PETM Shelf Dynamics and Diagenesis of the Piney Point Formation, Virginia Coastal Plain: Insights from Major and Trace Element Geochemistry

Session: Joint SGD-SEPM-IAS Focus on the Sedimentary Record of Climate Change (Posters)

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The Piney Point Formation, a glauconite-bearing, fossiliferous marl unit of post-Eocene age, provides a unique window into paleoenvironmental conditions following the Paleocene-Eocene Thermal Maximum (PETM). This study integrates geochemical and mineralogical analyses of 44 sediment samples from the USGS Banbury core (depths 250–299 ft), encompassing the Calvert, Old Church, Piney Point, and Nanjemoy Formations. Emphasis is placed on the Piney Point interval, where major oxide normalization, SEDNORM-derived normative mineralogy, and redox/salinity proxies (e.g., V/Cr, Ni/Co, Sr/Ba) were used to reconstruct depositional settings and evaluate diagenetic alteration.

Geochemical signatures from the Piney Point suggest deposition under suboxic, moderately restricted marine conditions with elevated salinity—conditions supported by high CaO, low TOC/TC ratios, and the abundance of authigenic glauconite. Compared to the underlying Nanjemoy and overlying Old Church and Calvert formations, the Piney Point reflects a distinct paleoenvironmental regime influenced by slowed sedimentation and early cementation processes. The data indicate significant post-depositional overprinting by carbonate recrystallization, limiting organic preservation.

These findings highlight the Piney Point Formation as a critical record of post-PETM environmental restructuring on the Atlantic Coastal Plain. Ongoing work aims to link these geochemical transitions to regional sea-level fluctuations and basin circulation patterns during early Paleogene recovery.

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

doi: 10.1130/abs/2025AM-8590

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