Authors / CoAuthors
Moss, G.D. | Cathro, D.L. | Austin, J.A., Jr.
Abstract
Sequence biostratigraphic analyses from five industry wells in the Northern Carnarvon Basin (NCB) are tied to seismic stratigraphic interpretations from an exceptional set of 3D and 2D seismic data. We document distribution patterns of ~286 benthic and 73 planktonic foraminiferal taxa in sidewall cores and ditch cuttings from Eocene to Pliocene intervals and supplement this with observations of other fossil groups, e.g., ostracods, bryozoa, coral and mollusc fragments, and lithological components, such as, authigenic calcite and quartz sands. Preservation of foraminiferal assemblages is extremely variable in Oligocene to latest Miocene stratigraphy, depending upon location of wells and interval investigated. Nonetheless, consistent, detectable faunal signals correlate between wells, and with prominent seismic horizons and sequences. The late Oligocene to middle Miocene is characterized by deeper-water benthic assemblages dominated by infaunal taxa and higher planktonic to benthic ratios. A cluster of stratigraphic events in the middle Miocene, including turnover in benthic foraminifera, is interpreted to record a regional flooding event (equivalent to TB2.3) at the beginning of the mid Miocene climatic optimum (~16-14.5 Ma). Following this event, seismically-defined geomorphic features include intensive karstification and incision on the clinoform front. All wells show a major transition to shallow-water, warm conditions on the shelf in the middle and late Miocene, with benthic assemblages dominated by larger foraminifera. This transition occurs progressively later in more basinward wells and appears to be a result of progradation. Geomorphic features in the late middle Miocene (~12 Ma), identified from 3D seismic analyses, show an intensification of earlier gully formation, resulting in submarine canyons. Detailed analyses of faunal patterns also provide evidence of higher-frequency sea-level fluctuations (0.5-3 Ma), not detected in seismic stratigraphic patterns.
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nonGeographicDataset
eCat Id
41196
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Keywords
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- External PublicationScientific Journal Paper
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- bathymetry
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- sequence stratigraphy
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- palaeontology
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- stratigraphy
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- marine
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- AU-WA
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
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2002-09-30T00:00:00
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[-22.0, -18.0, 113.0, 119.0]
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