Spatial change in carbonate precipitation and weathering in response to the Paleocene-Eocene Thermal Maximum warming from northern Iraq

Abstract

This study is a maiden attempt to investigate paleoenvironmental changes in northern Iraq at the time of the Paleocene-Eocene Thermal Maximum (PETM), focusing on carbonate precipitation and continental weathering dynamics. Two outcrop sections were analyzed; the Sinjar Formation at Dokan (northeastern Iraq) and the Aaliji Formation at Sinjar (northwestern Iraq). X-ray diffraction supplemented by scanning electron microscopy, major oxide geochemistry and carbonate stable isotopic data reveal an overall increase in carbonate precipitation during the PETM, with localized variations in dolomite indicating evaporative conditions shaped by paleogeographic and depositional settings. The high kaolinite-to-smectite and Sr/Ca elemental ratios suggest that humid conditions persisted during the recovery phase of the PETM, implying a shift into a more stable, humid climatic state following the hyperthermal event. Additionally, the PETM onset is marked by the emergence of kaolinite and a gradual rise in Chemical Index of Alteration (CIA) values indicating increased continental weathering and pedogenesis brought on by a warmer, wetter climate which may link to influence of both chemical weathering and physical (erosion). These findings provide new insights into how hyperthermal events could influence regional weathering, carbon cycling, and climate systems along the Tethyan margin.