Miocene wet and extreme arid climatic conditions in the Southeast Indian Ocean off Western Australia revealed by the lithology of Roebuck and Perth basins

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Author(s): McHugh, Cecilia M.; Groeneveld, Jeroen; Henderiks, Jorijntje; Renema, Willem; De Vleeschouwer, David; Christensen, Beth Anne; Potts, Donald Cameron; Fulthorpe, Craig; Bogus, Kara; Gallagher, Stephen J.
International Ocean Discovery Program, Expedition 356 Scientists
Author Affiliation(s): Primary:
CUNY, Queens College, Flushing, NY, United States
University of Bremen, Germany
Uppsala University, Sweden
Naturalis Biodiversity Center, Netherlands
Adelphi University, United States
University of California-Santa Cruz, United States
University of Texas at Austin, United States
University of Melbourne, Australia
Texas A&M University College Station, 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: Little is known about Miocene climate in the southeast Indian Ocean, off Western Australia. International Ocean Discovery Program (IODP) Expedition 356: Indonesian Throughflow drilled a latitudinal transect of sites along the modern shelf to investigate paleoclimatic and paleoceanographic conditions. We present lithologic evidence for aridity and changes in precipitation during the middle to late Miocene based on petrography and bulk mineralogy coupled to downhole wireline logs and chronology developed from biostratigraphy. Extreme arid conditions and sabhka facies similar to those occurring in the Red Sea today were present at northernmost Site U1464 (264 m water depth) during the middle Miocene (∼14-11.6 Ma). The sabhka to shallow subtidal facies is 100 m thick and occurs in dolomitic limestone. Evaporative conditions are manifested by anhydrite nodules with chicken wire texture, gypsum nodules, dissolution features and tidal structures such as load casts, ball and pillow structures and parallel laminae. At least two intervals, a few cm thick, of black, organic-rich, carbonate-poor dolostones suggest extreme evaporation and possible subaerial exposure in lagoonal settings. In contrast, at southernmost Site U1459 (192 m water depth) there is evidence of fluvial discharge related to wet climatic conditions that become more pronounced from the middle to the late Miocene (∼13-6 Ma). The section is 120 m thick and the main lithology is dolomite but siliciclastic minerals (quartz, k-feldspar) increase up-section. Intervals of quartz sandstone and glauconite deposition are interbedded in the dolomite. These results support increased fluvial discharge and likely a proximal shoreline. Large-scale climatic changes in Antarctica that occurred since the Middle Miocene Climatic Optimum, including its glaciation, and changes in global circulation are being investigated as possible triggers for the aridity and wet conditions in Western Australia.
Year of Publication: 2016
Research Program: IODP Integrated Ocean Drilling Program
IODP2 International Ocean Discovery Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Cenozoic; Climate change; Expedition 356; IODP Site U1459; IODP Site U1464; Indian Ocean; International Ocean Discovery Program; Miocene; Neogene; Paleoclimatology; Perth Basin; Roebuck Basin; Tertiary
Record ID: 2017051541
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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