Indonesian throughflow drove Australian climate from humid Pliocene to arid Pleistocene

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Author(s): Christensen, Beth Anne; Renema, Willem; Henderiks, Jorijntje; De Vleeschouwer, David; Groeneveld, Jeroen; Castañeda, Isla S.; Reuning, Lars; Bogus, Kara; Auer, Gerald; Ishiwa, Takeshige; McHugh, Cecilia; Gallagher, Stephen J.; Fulthorpe, Craig S.
Integrated Ocean Drilling Program, Expedition 356 Scientists, College Station, TX
Author Affiliation(s): Primary:
Adelphi University, Garden City, NY, United States
Naturalis Biodiversity Center, Netherlands
Uppsala University, Sweden
University of Bremen, Germany
University of Massachusetts Amherst, United States
RWTH Aachen University, Germany
Integrated Ocean Drilling Program, United States
University of Graz, Austria
University of Tokyo, Japan
Lamont-Doherty Earth Observatory, United States
University of Melbourne, Australia
University of Texas at Austin, 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: Our understanding of the onset of aridity in Australia and associated mechanisms is limited by the availability of long, continuous climate archives, particularly for the NW shelf in the Pliocene. Five sites were cored and logged on IODP Expedition 356, western Australian margin. Analysis of the natural gamma ray (NGR) suite of downhole logs, provide insights to the timing and rate of climate change. NGR data provide an outstanding tool to assess continental humidity (K%) and aridity (Th/K, Uppm); interpretations are supported with clay mineral data. We show progressive constriction of the Indonesian Throughflow (ITF) and the emerging Maritime Continent drove Australian climate to become drier and more variable. We identify 3 intervals of latest Miocene through early Pleistocene change: sudden onset of humidity at ∼5.5 Ma (Humid Interval), followed by decreased humidity (Transition Interval) and establishment of the NW dust pathway (Arid Interval) at ∼2.3 Ma. The Humid Interval is associated with the Western Pacific Warm Pool (WPWP) expansion west to the South China Sea and higher Indian Ocean SSTs. Our study of the NW region confirms wetter climates ringed the arid center during the early Pliocene. Reduced moisture availability began at ∼3.3 Ma, coincident with cooling in the WPWP and elsewhere, global atmospheric circulation constriction and Indian Ocean subsurface freshening and cooling, a direct response to ITF constriction. Greatest aridity and the onset of the modern dust pathway, documented in Th/K and Uppm logs beginning ∼2.3 Ma, is coincident with orbitally-controlled climatic change, and reorganization of Indian Ocean circulation. Our data indicate Australian climate is driven by tectonic and oceanographic changes in the ITF. Such changes altered regional atmospheric moisture transport and Indian Ocean circulation patterns and led to a shift from Pacific to Indian Ocean influence on the NW Australian climate, well after the intensification of northern hemisphere glaciation. We conclude that the Maritime Continent is the switchboard modulating teleconnections between monsoonal and glacial climate systems.
Year of Publication: 2016
Research Program: IODP2 International Ocean Discovery Program
Key Words: 24 Surficial Geology, Quaternary Geology; Asia; Cenozoic; Core; Expedition 356; Far East; Indian Ocean; Indonesia; International Ocean Discovery Program; Marine sediments; Neogene; Pacific Ocean; Paleoclimatology; Pleistocene; Pliocene; Quaternary; Sediments; Tertiary
Record ID: 2017062450
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by, and/or abstract, Copyright, American Geophysical Union, Washington, DC, United States

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