Abstract
The Late Cretaceous ‘greenhouse’ world witnessed a transition from one of the warmest climates of the past 140 million years to cooler conditions, yet still without significant continental ice. Low-latitude sea surface temperature (SST) records are a vital piece of evidence required to unravel the cause of Late Cretaceous cooling, but high-quality data remain illusive. Here, using an organic geochemical palaeothermometer (TEX86), we present a record of SSTs for the Campanian–Maastrichtian interval (~83–66 Ma) from hemipelagic sediments deposited on the western North Atlantic shelf. Our record reveals that the North Atlantic at 35 °N was relatively warm in the earliest Campanian, with maximum SSTs of ~35 °C, but experienced significant cooling (~7 °C) after this to <~28 °C during the Maastrichtian. The overall stratigraphic trend is remarkably similar to records of high-latitude SSTs and bottom-water temperatures, suggesting that the cooling pattern was global rather than regional and, therefore, driven predominantly by declining atmospheric pCO2 levels.
Highlights
The Late Cretaceous ‘greenhouse’ world witnessed a transition from one of the warmest climates of the past 140 million years to cooler conditions, yet still without significant continental ice
The maximum TEX8H6-based sea surface temperature (SST) estimates of 28–35 °C from the Shuqualak–Evans borehole suggest that Late Cretaceous climate was consistently warmer at B35 °N than at present, and this conclusion is broadly true even using the TEX8L6 calibration (Supplementary Fig. 2)
These estimates of low-latitude SST are consistent with recently published TEX86 data from Israel[22], which suggest a range of SSTs from B23 to 33 °C during the Campanian–Maastrichtian at a palaeolatitude of 5° to 15 °N
Summary
The Late Cretaceous ‘greenhouse’ world witnessed a transition from one of the warmest climates of the past 140 million years to cooler conditions, yet still without significant continental ice. TEX8H6 has been widely viewed as the most appropriate calibration for past greenhouse climates and is used here for discussion of our estimates of Cretaceous SSTs, as our measured values of TEX86 are high and the study site is a low-latitude setting[14,21].
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