Tracing Ancient Warmth: Stable Isotope and Sedimentological Insights into the PETM of the Muthaymimah Formation, United Arab Emirates

Abstract

The Paleocene-Eocene Thermal Maximum (PETM) represents a short (ca.100 - 200 k years) but intense warming episode that resulted in a significant perturbation in the Earth’s climate and carbon cycle 56 million years ago.The Arabian Platform occupies an important low latitude site for recording this episode, however, there are limited geochemical and sedimentological records of the PETM from this region. High-resolution sampling and integrated approaches are necessary to understand how low latitude, shallow marine deposits respond to abrupt climate change such as the PETM. To address this gap in the records, we integrate sedimentological and stable isotope data with global stratigraphic models to document the depositional and sedimentological changes across the Paleocene-Eocene interval within the Muthaymimah Formation (UAE) and establish the first high-resolution chemostratigraphic record of the PETM from the Arabian PlatformWe focus on two chronologically well-constrained stratigraphic sections, the Qarn El Barr outcrop in the central region of Sharjah Emirate and the Mundassah outcrop southeast of Al Ain city, Abu Dhabi Emirate. The Paleocene/Eocene boundary is located between the biozones NP 9a and NP 9b using the Calcareous nannoplankton biozonation scheme.We examined 49 samples from Qarn El Barr stratigraphic section and 495 samples from the Mundassah stratigraphic section. This data has enabled us to more accurately identify the Paleocene-Eocene transition in the UAE.We performed stable Carbon (δ13C) and Oxygen (δ18O) isotope analysis on bulk carbonate across both sections. The timing and position of the PETM in both sections was established by preliminary stable isotope analysis of the sediments. Subsequent high-resolution stable isotope analysis confirms this signal, documenting the first record of the PETM in the UAE. Our δ13C stratigraphy reveals a 2.5‰ negative excursion, consistent with the published negative carbon excursions for the PETM in shallow marine environments elsewhere. We further explore temperature changes and faunal turnover within this interval.Interestingly, field observations do not show any dramatic changes in the sedimentological characteristics: At the Qarn El Barr outcrop the PETM is located near the top of the thin-bedded grey marls, just below the transition to a yellow marly unit, while in Mundassah section, the PETM is located at a thin-bedded wackestone interval above a calciturbidite horizon and thin-bedded mudstone. We integrate our nannoplankton and geochemical records with these sedimentological observations to shed new light on the PETM environments in the UAE.