Linking changes in Indonesian throughflow dynamics with the Middle Pleistocene transition

Author(s): Petrick, Bernard; Auer, Gerald; Christensen, Beth Anne; De Vleeschouwer, David; Reuning, Lars; Martinez-Garcia, Alfredo; Haug, Gerald H.; Gallagher, Stephen J.; Fulthorpe, Craig; Bogus, Kara
Author Affiliation(s): Primary:
Max Planck Institute for Chemistry, Mainz, Germany
Other:
University of Graz, Austria
Adelphi University, United States
University of Bremen, Germany
RWTH Aachen University, Germany
Swiss Federal Institute of Technology, Switzerland
University of Melbourne, Australia
University of Texas at Austin, United States
International Ocean Discovery Program, United States
Volume Title: AGU 2016 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2016; American Geophysical Union 2016 fall meeting, San Francisco, CA, Dec. 12-16, 2016. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: The Mid-Pleistocene Transition (MPT; ∼1.4-0.4 Ma) represents a fundamental shift in the Earth's climate state. While there is high-resolution data covering the MPT from globally distributed archives, only sparse evidence exists on changes in the heat exchange between the Pacific and Indian Oceans, representing a crucial part of the global thermohaline circulation. Deciphering the influence of this heat exchange via the Indonesian Throughflow (ITF) is an important step in understanding the causes of the MPT. The Leeuwin Current off Western Australia is directly influenced by the ITF and can be used to reconstruct ITF variability during the MPT. Today, the Leeuwin Current is the only southward flowing eastern boundary current in the southern hemisphere. The onset of the current is unknown, but is proposed to have occurred ∼1 Ma and was likely related to significant changes in ITF dynamics during the MPT. Here we present the first continuous reconstruction of changes in the Leeuwin Current during the MPT using data from IODP Expedition 356 Site U1460. The site is located at 29°S in the path of the current. We reconstruct paleoenvironmental variability by combining XRF, organic geochemistry, ICP-MS, and XRD data with shipboard results, to reconstruct Leeuwin Current and ITF variability. High sedimentation rates (∼30 cm/ka) at Site U1460 provide the opportunity for high-resolution reconstruction of ITF variability during the MPT. Initial analyses show clear indications that upwelling off Western Australia intensified during the MPT, indicated by increased primary productivity related to increased nutrient levels, from 900-600 ka. Stronger upwelling in turn indicates a reduction in ITF, and thus implies that the heat transport from the Pacific to the Indian Ocean significantly diminished during the MPT. Our results suggest, that reduced heat exchange via the ITF played a major role in forcing the climatic shift towards the 100-kyr icehouse world of the Pleistocene.
Year of Publication: 2016
Research Program: IODP Integrated Ocean Drilling Program
IODP2 International Ocean Discovery Program
Key Words: 24 Surficial Geology, Quaternary Geology; Cenozoic; Climate change; Expedition 356; Holocene; IODP Site U1460; International Ocean Discovery Program; Middle Pleistocene; Paleoclimatology; Pleistocene; Quaternary
Record ID: 2017051570
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data supplied by, and/or abstract, Copyright, American Geophysical Union, Washington, DC, United States

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