New Insights into the Paleocene-Eocene Thermal Maximum (PETM) in the UAE: Geological and Paleoclimatic findings from the Muthaymimah Formation

The Paleocene/Eocene Thermal Maximum (PETM) marks a short but intense climate warming that occurred 56 million years ago and lasted for about ca.100 - 200 k years. It represents a significant change in the carbon cycle and Earth’s climate.

PETM sites from the Arabian Platform occupy an important low latitude site for recording this excursion. However, to date, specific information about the PETM event in the region is relatively rare as the previous studies have mostly focused on hydrocarbon production and related investigative approaches to biostratigraphy, diagenesis, mineralogy, and geochemistry. High-resolution and integrated approaches are necessary to understand how the low latitude and shallow marine deposits respond to abrupt climatic changes such as the PETM, and therefore to tie regional stratigraphy to the global stratigraphic models and correlate the shallow marine to different depositional environments.

The objective of the study is to use a multidisciplinary approach and integration of field observations, sedimentology, paleontology and stable isotopes analyses to record the depositional and sedimentological changes of the Paleocene-Eocene interval within the Muthaymimah Formation in the UAE, for the first time. In this study four stratigraphic sections of Muthaymimah Formation have been analysed, Qarn El Barr, Malieha & Thanyes outcrops in the central region of Sharjah Emirate and Mundassah section, southeast of Al Ain city, Abu Dhabi Emirate.

We examined sedimentological changes across the Muthaymimah Formation using field observations and stratigraphic logging. Initially 64 samples were analyzed for their calcareous nanoplanktons content to determine calcareous nanoplankton assemblages and the age of each stratigraphic section and in order to identify a biozonation and to locate the Palaeocene/Eocene boundary. According to previously published work in the region, the Paleocene/Eocene boundary is located between biozones NP9b and NP10. Our preliminary investigation showed that biozones NP7/8, NP9a and NP10 are represented in Mundassah section, bracketing the PETM. Biozones NP3 and NP7/8 are described in the lower part of the Malieha section. Biozone NP10 was located at Qarn El Barr, while Paleocene sediments have been tentatively identified above the well-defined late Cretaceous sediments at Thanyes.

Based on the findings of this lower resolution preliminary data set, we carried out a further detailed investigation to better constrain the Paleocene/Eocene boundary in the studied sections. A total of 213 samples from four logged sections are used to produce a high-resolution biozonation of the calcareous nannoplankton analyses for Muthaymimah Formation. In addition, we constructed the first chemostratigraphic sections using Carbon and Oxygen stable isotope ratio analysis of the Muthaymimah Formation in the UAE. A total of 534 further samples have been collected from the key four outcrops in November 2024. We focused on the Mundassah stratigraphic section, where the PETM has already been bracketed by our lower resolution analysis, collecting 403 samples. In addition, 51 samples from the Qarn El Barr stratigraphic section, 23 from the Malieha stratigraphic section, and 57 samples from Thanyes stratigraphic section were collected.

Based on these analyses, we establish the first detailed record of the PETM from the field outcrops in the UAE.