Climate variability and siliciclastic deposition on a carbonate margin; Neogene of the northwest shelf of Australia

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Author(s): Tagliaro, Gabriel; Fulthorpe, C.; Gallagher, S. J.; McHugh, C.; Kominz, M. A.; Lavier, L.
Author Affiliation(s): Primary:
University of Texas at Austin, Austin, TX, United States
University of Melbourne, Melbourne, Victoria, Australia
CUNY Queens College, Flushing, NY, United States
Western Michigan University, Kalamazoo, MI, United States
Volume Title: AGU 2017 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2017; American Geophysical Union 2017 fall meeting, New Orleans, LA, Dec. 11-15, 2017. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: The Bare Formation represents a unique episode of Neogene siliciclastic deposition on the carbonate-dominated Australian Northwest Shelf (NWS). International Ocean Discovery Program (IODP) Expedition 356 drilling results, coupled with interpretation of 3D seismic data, allow us to constrain the timing of siliciclastic deposition and the associated sedimentary processes. IODP Sites U1462, U1463 and U1464 provide age control that reveals the relationship of the Bare Fm. to the adjacent carbonate sediments. The Bare Fm. is preceded by middle to late Miocene shelf exposure and karstification. Elongate beach barrier deposits with small lobate deltas to the NE developed during the late Miocene. However, fluvial deposition increased markedly in the Zanclean, resulting in development of a large tide-and-wave-influenced delta, with evidence of tidal channels, comprising the thickest component of the Bare Fm. Siliciclastic input decreased in the Piacenzian, leading to margin retreat and final termination near the Plio-Pleistocene boundary. The results correlate with regional climate and sedimentary records derived from Sites U1459, U1463 and U1464, that indicate an arid middle to late Miocene, followed by a humid interval in the Zanclean and a return to arid conditions during the Piacenzian. Therefore, we suggest that fluctuation of surface runoff patterns in the continental hinterlands is the primary control of Bare Fm. evolution. Hence, Neogene siliciclastic distribution is a result of regional climate variability on the NWS. Up to 40 km of shoreline advance is verified in the Late Miocene and Pliocene, an example of climate-driven modification of a continental margin. Additionally, longshore transport intensifies during the Pliocene humid interval, causing NE migration of the deltaic system. Sedimentary and climate transitions are linked to reorganization of Indian Ocean paleoceanography, accompanying northward migration of the Australian continent and progressive restriction of the Indonesian Throughflow.
Year of Publication: 2017
Research Program: IODP Integrated Ocean Drilling Program
IODP2 International Ocean Discovery Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Bare Formation; Carbonates; Cenozoic; Climate change; Expedition 356; Global change; IODP Site U1462; IODP Site U1463; IODP Site U1464; International Ocean Discovery Program; Neogene; Paleoclimatology; Siliciclastics; Tertiary
Record ID: 2018074823
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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