Product catalogue
Leg 189 Synthesis: Cretaceous-Holocene History of the Tasmanian Gateway
Ocean Drilling Program (ODP) Leg 189 drilled five sites in bathyal depths on submerged continental blocks in the Tasmanian Gateway, to help refine the hypothesis that its opening near the Eocene/Oligocene boundary led to formation of the Antarctic Circumpolar Current (ACC), progressive thermal isolation of Antarctica, climatic cooling, and development of an Antarctic ice sheet. In all, 4539 m of marine and largely continuous upper Maastrichtian to Holocene core were recovered, with a recovery rate of 89%. The sedimentary sequence broadly consists of shallow marine mudstones until the late Eocene, glauconitic siltstones during the late Eocene, and pelagic carbonates thereafter. The microfossils in the mudstones and siltstones are largely palynomorphs and diatoms, and those in the carbonates are largely nannofossils and foraminifers.
During the Late Cretaceous, northward movement of Australia away from Antarctica commenced, forming the Australo-Antarctic Gulf (AAG). However, a Tasmanian land bridge at 70?-65?S almost completely blocked the eastern end of the widening AAG until the late Eocene, there being no evidence of extensive current circulation across the ridge until the earliest Oligocene. Prior to the Oligocene, muddy marine siliciclastic sediments were deposited in temperate seas. During the late Eocene, the northeastern AAG was warmer and less ventilated than the gradually widening southwest sector of the Pacific Ocean, which was affected by a cool, northwesterly flowing boundary current ? a difference that may have existed since the Maastrichtian. In the late Eocene (~37 Ma), the Tasmanian land bridge and its broad shelves began to subside, currents swept the still-shallow offshore areas, and condensed glauconitic siltstones were deposited. Palynological and diatom evidence suggest a general cooling. The southwestern South Tasman Rise finally separated from Antarctica at the time of the Eocene/Oligocene boundary (~33.5 Ma), the rise subsided, and the continental margin of Tasmania collapsed. The Tasmanian Gateway opened to deep water, disrupting oceanic circulation at high southern latitudes, and leading to one of the major climatic shifts of the Cenozoic.
Thereafter, a marked reduction in siliciclastic supply, and the flow of warm currents from northern latitudes, favored the deposition of carbonate. At the eastern sites, deposition of Oligocene bathyal carbonates directly followed an unconformity caused by the onset of the ACC, but change was more gradual in the west. In contrast, siliceous biogenic sediments typified the Antarctic margin, now isolated from warm water by the ACC. Steady northward movement kept the Tasmanian region north of the Polar Front throughout the Neogene, and pelagic carbonates accumulated.
Simple
Identification info
- Date (Publication)
- 2004-01-01T00:00:00
- Citation identifier
- Geoscience Australia Persistent Identifier/https://pid.geoscience.gov.au/dataset/ga/61623
- Cited responsible party
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Role Organisation / Individual Name Details Author Exon, N.F.
1 Author Kennett, J.P.
2 Author Malone, M.J.
3
- Point of contact
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Role Organisation / Individual Name Details Custodian ED
Owner Commonwealth of Australia (Geoscience Australia)
Custodian Commonwealth of Australia (Geoscience Australia)
Voice
- Topic category
-
- Geoscientific information
Extent
))
- Maintenance and update frequency
- Unknown
- Keywords
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External Publication
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Scientific Journal Paper
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- Theme
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marine
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- Keywords
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AU-TAS
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- Australian and New Zealand Standard Research Classification (ANZSRC)
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Earth Sciences
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- Keywords
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Published_External
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Resource constraints
- Title
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Creative Commons Attribution 4.0 International Licence
- Alternate title
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CC-BY
- Edition
-
4.0
- Access constraints
- License
- Use constraints
- License
Resource constraints
- Title
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Australian Government Security ClassificationSystem
- Edition date
- 2018-11-01T00:00:00
- Classification
- Unclassified
- Language
- English
- Character encoding
- UTF8
Distribution Information
- Distributor contact
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Role Organisation / Individual Name Details Distributor Commonwealth of Australia (Geoscience Australia)
Voice
- OnLine resource
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View the article in Scientific Results, Vol. 189, September 2004
View the article in Scientific Results, Vol. 189, September 2004
- Distribution format
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html
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Resource lineage
- Statement
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Unknown
- Hierarchy level
- Non geographic dataset
- Other
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External Publication
- Description
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Source data not available.
Metadata constraints
- Title
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Australian Government Security ClassificationSystem
- Edition date
- 2018-11-01T00:00:00
- Classification
- Unclassified
Metadata
- Metadata identifier
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urn:uuid/a05f7892-c32f-7506-e044-00144fdd4fa6
- Title
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GeoNetwork UUID
- Language
- English
- Character encoding
- UTF8
- Contact
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Role Organisation / Individual Name Details Point of contact Commonwealth of Australia (Geoscience Australia)
Voice
Type of resource
- Resource scope
- Non geographic dataset
- Name
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nonGeographicDataset
Alternative metadata reference
- Title
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Geoscience Australia - short identifier for metadata record with
uuid
- Citation identifier
- eCatId/61623
- Date info (Revision)
- 2018-04-22T08:24:05
- Date info (Creation)
- 2004-09-17T00:00:00
Metadata standard
- Title
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AU/NZS ISO 19115-1:2014
Metadata standard
- Title
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ISO 19115-1:2014
Metadata standard
- Title
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ISO 19115-3
- Title
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Geoscience Australia Community Metadata Profile of ISO 19115-1:2014
- Edition
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Version 2.0, September 2018
- Citation identifier
- https://pid.geoscience.gov.au/dataset/ga/122551