Acta Petrologica et Mineralogica

The Paleocene to Early Eocene was an important climate transition period in the Cenozoic Era, with multiple extreme heat events leading to a weakening of the earth's surface carbon sink capacity and fluctuations in sea levels. Since the Eocene epoch, marine sediment has been recorded in only three areas in China, and the Karatal Formation in southwest Tarim retains a complete record of marine transgression during this period, making it an important stratum for studying the Cenozoic paleoclimate and the evolution of the paleo-Tethys Ocean. This article focuses on the study of extreme climate sedimentary characteristics recorded by the Karatal Formation. The results show that: ① the Karatal Formation records a reliable astronomical cycle, with a depositional duration of 6.6 Ma, consistent with the Lutetai Stage; ② Five components of the storm sequence, namely grain sequence bedding, parallel bedding, mound cross bedding, wavy bedding and massive mudstone, observed in the Kalatal Formation, indicating that the Tarim Basin was in the tropical-subtropical low-latitude area where storms frequently occurred during the sedimentary period; ③ Affected by differences in sedimentary facies and hydrodynamics, 10 types of ooids have developed, including radial ooid, concentric ooid, superficial ooid, complex ooid, elliptical ooid, and eccentric ooid of primary sedimentary origin, as well as micritic ooid, deformed ooid, negative ooid, and dolomitized ooid of secondary alteration origin. In the middle Eocene, abnormal climate events pushed up sea level and seawater entered the Tarim Basin, which lasted until the end of the Lutetai Stage. During the sedimentation period, under the control of greenhouse effect, storms occurred frequently, CO₂ concentration increased, seawater evaporation increased, and continental weathering intensified. The long-term deterioration of the environment resulted in opportunistic selection characteristics of biological fossils. This article supplements the research on abnormal climate in the Cenozoic era in China with evidence from marine profiles.

Tarim Basin; Karatal Formation; storm action; ooid; extreme heat events