Continuous Sediment Sourcing and Changes in Weathering During the PETM in the Salisbury Embayment

Abstract The Paleocene‐Eocene Thermal Maximum, or PETM, a period of extreme warming (ca. 56 Mya), was accompanied by changes to regional climates including warming and dramatic changes in precipitation patterns. In particular, marginal marine sediments record a marked increase in kaolinite content, often viewed as evidence of increased chemical weathering attributed to climate‐driven shifts in the intensity and latitude of precipitation. It remains unclear whether this kaolinite formed during the PETM, or was reworked from older deposits, thus representing a shift in physical transport, with differing interpretations existing both between and within sections. Here, we attempt to resolve this debate within the Mid‐Atlantic Coast. We utilize lithium isotopes in a mid‐Atlantic margin shallow marine section, South Dover Bridge, to characterize changes in weathering congruency, as well as strontium and lead isotopes to constrain changes in provenance. Lithium isotope ratios decrease by ∼3‰ which is interpreted as a decrease in water‐rock interaction time, and while there is variation in the radiogenic isotopes, they are largely within the bounds of the proposed kaolinite source, the late Cretaceous Raritan formation, not only during the PETM, but during the late Paleocene and the recovery as well. We compare these results to high‐resolution climate model output of the study site and find an increase in the intensity of precipitation extremes at the onset of the PETM. These results are interpreted as an increase in both physical weathering and chemical alteration taking place during the PETM, driven by increased temperatures and hydrologic activity, with a relatively constant sediment sourcing.