215 / 2025-04-15 10:14:46

Shallow-Water Carbonate Response to the Paleocene–Eocene Thermal Maximum in the Eastern Tethys: Insights from the Lower Indus Basin, Pakistan

carbonate,Carbon isotope excursion,Indus Basin,Paleocene Eocene Thermal Maximum,Tethys

Theme 3: Earth-Life Co-evolution Through Time > Session 3e: Mass extinctions and lesser calamities in the marine realm

Abstract

The Paleocene-Eocene Thermal Maximum (PETM) occurring approximately 56 million years ago was a global warming event characterized by substantial increases in mean surface temperatures leaving an indelible mark on the Earth. This event had significant biotic impacts including a major extinction in marine ecosystems and a notable turnover in larger benthic foraminifera (LBF). Although the PETM is extensively studied as a model for future climate change but considerable gaps remain in our understanding of its impact particularly in shallow marine environments within the Indus Basin. To address this gap, we conducted a study of the late Paleocene to early Eocene Dungan Formation exposed at Zaranda area, Pakistan. The PETM is identified along with its biogeochemical impacts, in the shallow marine carbonate ramp deposits of Dungan Formation from the eastern Tethys, Lower Indus Basin of Pakistan. A sudden drop in bulk carbon isotope values marks the onset of the PETM. At 23 meters a prominent shift in δ¹³C is observed from +4.09‰ to +2.71‰ which is interpreted as the onset of the PETM carbon isotope excursion (CIE). The bulk δ¹⁸O profile exhibits a broad range of values spanning from -3.62‰ to -10.09‰ a pronounced negative spike in δ¹⁸O values coincides with the onset of the negative carbon isotope excursion (CIE) indicating a significant warming event associated with the PETM. The Carbon Isotope Excursion (CIE) is linked to a significant turnover in larger benthic foraminifera (LBF) marked by the emergence of species such as Alveolina ellipsoidalis, Glomalveolina minutula, Assilina dandotica, and Ranikothalia sidenesis. Concurrently, this period saw the disappearance of species including Glomalveolina levis, Miscellanea juliettae, Azzarolina daviesi, Karsella hottinger, Kathina prenavuti, and Kathina selveri. Our study indicates that the Paleocene-Eocene Thermal Maximum (PETM) had a significant effect on shallow marine benthic foraminifera on the western side of the central eastern Tethys.