AN ORBITALLY PACED, NEAR-COMPLETE RECORD OF CAMPANIAN CLIMATE AND SEDIMENTATION IN THE MISSISSIPPI EMBAYMENT, USA

The Campanian (83.6–72.1 Ma) marked the transition from the ‘hot greenhouse’ of the mid-Cretaceous to the ‘cool greenhouse’ of the Maastrichtian. Despite being the longest stage of the Late Cretaceous, the Campanian is poorly understood and represents a “gap” in the astronomically tuned time scale. Few records are described outside of Europe, and only a limited portion of the sediments preserved show an imprint of orbitally driven changes in insolation. Independent age constraints are limited, and the seeming absence of major climatic events hampers correlation.

Here we present a high-resolution lithological and elemental record from the Shuqualak–Evans Borehole (Mississippi, USA), which intersects a sequence of hemipelagic marls and chalks deposited at ~35°N. This core shows prominent rhythmicity, reflecting variations in land–sea interaction in the Gulf Coast region. This ~10 Myr-long record of Campanian climate reveals a hierarchy of cycles, corresponding to the periodicities of eccentricity-modulated precession, and with a surprisingly pervasive imprint of obliquity forcing. Additionally, the identification of 2.4 Myr minima may allow anchoring of the Shuqualak sequence to the absolute time-scale. The new cyclostratigraphic framework is in good agreement with available δ¹³C data and biostratigraphic information. Re-interpreted carbon-isotope excursions in the Shuqualak record correspond well with events identified and dated in the European chalk sea, including the Campanian–Maastrichtian Boundary Event (CMBE), the Late Campanian Event (LCE), and potentially the Mid-Campanian Event (MCaE). The new age model developed in this study confirms that the Shuqualak core encompasses almost the entire Campanian and may represent the most complete record of this time-interval outside Europe. The new data from the Mississippi Embayment give a unique glimpse into Campanian climate dynamics and provide a framework for future palaeoclimate studies.