Terrestrial responses of low-latitude Asia to the Eocene–Oligocene climate transition revealed by integrated chronostratigraphy
- 1State Key Laboratory for Mineral Deposits Research, Key Laboratory of Surficial Geochemistry, Ministry of Education, School of Earth Sciences and Engineering, 210046 Nanjing, China
- 2Department of Earth Sciences, The University of Hong Kong, Hong Kong, China
- 3State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, 510275 Guangzhou, China
- 4College of Earth Sciences, Jilin University, 130061 Changchun, China
- 5Department of Earth Sciences, Zhejiang University, Hangzhou, China
- 6Research Center of Paleontology and Stratigraphy, Jilin University, 130026 Changchun, China
Abstract. The Paleogene sedimentary records from southern China hold important clues to the impacts of the Cenozoic climate changes on low latitudes. However, although there are extensive Paleogene terrestrial archives and some contain abundant fossils in this region, few are accurately dated or have a temporal resolution adequate to decipher climate changes. Here, we present a detailed stratigraphic and paleomagnetic study of a fossiliferous late Paleogene succession in the Maoming Basin, Guangdong Province. The succession consists of oil shale of the Youganwo Formation (Fm) in the lower part and the overlying sandstone-dominated Huangniuling Fm in the upper part. Fossil records indicate that the age of the succession possibly spans the late Eocene to the Oligocene. Both the Youganwo Fm and the overlying Huangniuling Fm exhibit striking sedimentary rhythms, and spectral analysis of the depth series of magnetic susceptibility of the Youganwo Fm reveals dominant sedimentary cycles at orbital frequency bands. The transition from the Youganwo oil shale to the overlying Huangniuling sandstones is conformable and represents a major depositional environmental change from a lacustrine to a deltaic environment. Integrating the magnetostratigraphic, lithologic, and fossil data allows establishing a substantially refined chronostratigraphic framework that places the major depositional environmental change at 33.88 Ma, coinciding with the Eocene–Oligocene climate transition (EOT) at ∼ 33.7 to ∼ 33.9 Ma. We suggest that the transition from a lacustrine to deltaic environment in the Maoming Basin represents terrestrial responses to the EOT and indicates prevailing drying conditions in low-latitude regions during the global cooling at EOT.