Tectonic and climatic controls on sediment transport to the Southeast Indian Ocean during the Eocene: New insights from IODP Site U1514

• Published in: Global and Planetary Change
• Main Authors: Wang, Wei, Colin, Christophe, Xu, Zhaokai, Lim, Dhongil, Wan, Shiming, Li, Tiegang
• Other Authors: Géosciences Paris Saclay (GEOPS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2022
• Subjects: Eocene; Paleoclimate; Southern mid-high latitudes; Sr and Nd isotopes; Clay minerals; Provenance; [SDU]Sciences of the Universe [physics]; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Indian; Southern Ocean; Antarc*; Antarctica
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-03846935; https://doi.org/10.1016/j.gloplacha.2022.103956

International audience The Eocene was a critical period of global plate reorganization and it also saw the Earth's climate transition from the warmhouse state to the coolhouse state. Reconstructing the Eocene sedimentary history in the climate-sensitive Southern Ocean is important for understanding paleoenvironmental changes in response to the accelerated Australia/Antarctica separation and global cooling throughout the middle and late Eocene. Here, we present the first detailed multiproxy record of a continuous sequence from International Ocean Discovery Program (IODP) Site U1514 in the Mentelle Basin off southwestern Australia. Our aim is to reconstruct the sediment provenances and paleoenvironmental evolution in response to the abovementioned climatic and tectonic changes in the mid-high southern latitudes during the Eocene. Provenance analyses based on Sr-Nd isotopes, trace elements, and clay mineral assemblages suggest that Eocene sediments at Site U1514 predominantly originated from the southwestern Australian continent and the Naturaliste Plateau. Sediment provenance variations during the middle Eocene indicate that the onset of fast separation between Australia and Antarctica at 43 Ma caused an increased supply of volcanic materials from the Naturaliste Plateau between 43 and 38 Ma. Terrigenous inputs to the Mentelle Basin during the middle Eocene were primarily controlled by paleoclimate changes rather than tectonic processes because coeval clay mineralogical changes (higher kaolinite/smectite ratio and MAR kaolinite ) indicate a period of stronger physical erosion and chemical weathering on the western Australian continent that resulted in increased terrigenous materials delivered to the Mentelle Basin. Our results reveal a 5 Myr-long (43-38 Ma) warming reversal in the southern mid-high latitudes, providing an exception to the generally short-lived (10-100 kyr-long) hyperthermals that interrupted the long-term global cooling throughout the middle to late Eocene. As for the late Eocene (38-37 Ma), ...