Middle-late Miocene siliciclastic influx on the Australian northwest shelf; origins and potential links to global events

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http://abstractsearch.agu.org/meetings/2016/FM/PP42A-02.html
Author(s): Tagliaro, Gabriel; Fulthorpe, Craig; Lavier, Luc L.; Gallagher, Stephen J.
International Ocean Discovery Program, Expedition 356 Scientists
Author Affiliation(s): Primary:
University of Texas, Institute for Geophysics, Austin, TX, United States
Other:
University of Melbourne, Australia
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 Bare Formation in the Northern Carnarvon Basin represents a unique episode of siliciclastic deposition within a carbonate-dominated system. Recent drilling by International Ocean Discovery Program (IODP) Expedition 356, coupled with interpretation of 3D seismic data, provide an opportunity to constrain the sedimentary processes involved in the deposition of these siliciclastics. Two interpretations of the depositional processes responsible for the Bare Fm. have been proposed: 1) shelf and shelf-edge deltas associated with the advance of a fluvial system across the shelf, and 2) a beach barrier system, involving reworking of sediment on the paleo-shelf. We reinterpret the stratigraphy, depositional system, and timing of the Bare Fm. Seismic data are tied to IODP Site U1462, which provides age control and illustrates the relationship of the Bare Fm. to the adjacent carbonate sediments. The Bare Fm. was initiated in the middle Miocene and Expedition 356 results do not refine that age because of absence of diagnostic microfossils. However, seismic geomorphology enables us to redefine the Bare Fm. top as Messinian, younger than the Tortonian age previously assigned. By 5.59 Ma, siliciclastic deposition had transitioned to a mixed siliciclastic-carbonate system, with a continuous decrease in siliciclastic content toward the top of Pliocene. The Bare Fm. comprises at least two successive northeastward-migrating lobate mounds. Benthic foraminiferal biofacies indicate an outer shelf/upper bathyal depositional environment, suggesting that seismic signatures basinward of the siliciclastics, previously interpreted as karst, have other causes (possibly pockmarks). The middle to late Miocene was a period when anomalous tectonic and climatic activity led to an abrupt increase in continental-margin sedimentation worldwide. Recovery of anhydrite coeval with active Bare Fm. deposition indicates that it was deposited during a period of regional aridity and low relative sea level.
Year of Publication: 2016
Research Program: IODP Integrated Ocean Drilling Program
IODP2 International Ocean Discovery Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Bare Formation; Cenozoic; Expedition 356; IODP Site U1462; Indian Ocean; International Ocean Discovery Program; Middle Miocene; Miocene; Neogene; Tertiary; Upper Miocene
Record ID: 2017051539
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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