Authors / CoAuthors
Shafik, S.
Abstract
The nannostratigraphy of material dredged from the Fremantle Canyon, west of Perth (Western Australia), indicates that the Maastrichtian-Miocene section in the South Perth Basin is more complete than contemporaneous sections in the Perth Abyssal Plain and on the Naturaliste Plateau. The data point to a possible continuous sequence through most of the Paleocene and the entire Eocene in the Fremantle Canyon. In addition to the five rock units previously known to form the Maastrichtian-Miocene succession of the Perth Basin, two (or possibly three) new units have been discovered. The new units, yet to be named, are of Early Eocene and mid Oligocene age; in addition a previously unreported Lower Paleocene sequence could be the lower extension of the Kings Park Formation offshore. The unnamed new Lower Eocene unit fills the stratigraphic gap between the (mainly) Upper Paleocene Kings Park Formation and the Middle Eocene Porpoise Bay Formation. The unnamed new mid (upper Lower) Oligocene unit fits between the Upper Eocene Challenger Formation and the Lower-Middle Miocene Stark Bay Formation, still leaving a large stratigraphic gap between these two formations. The lithological evidence, supported by nannofossil data, indicates that the Porpoise Bay and Challenger Formations merge into a single unit along the canyon walls. This unit is similar to the Lower Eocene and Paleocene carbonates there. A widespread Late Maastrichtian transgression over the Carnarvon and Perth Basins, reaching the Great Australian Bight Basin as an ingression, is seen in the Fremantle Canyon as occurrences of nannofossil association characteristic of the Upper Maastrichtian Breton Marl onshore. Several lines of evidence are discussed to suggest that the onshore Kings Park Formation represents a rapid sea level rise and culmination of the Paleocene transgression over the Perth Basin. Indications of a previously reported significant Middle Eocene reworking episode are recorded at the right level in the Fremantle Canyon succession. Middle Eocene microplanktic components found in the newly reported mid Oligocene of the canyon are thought to have been derived from the Naturaliste Plateau during a major Oligocene erosional event, whose effects have been recorded previously in several DSDP sites in the Southwest Pacific region.
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document
eCat Id
81284
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Keywords
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- GA PublicationJournal
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- WA
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_External
Publication Date
1991-01-01T00:00:00
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geoscientificInformation
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BMR Journal of Australian Geology and Geophysics 12:1:65-91
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