Middle and Late Eocene Great Australian Bight lithobiostratigraphy and stepwise evolution of the southern Australian continental margin
Middle to Upper Eocene carbonates recovered at ODP Leg 182 sites from the Great Australian Bight comprise three packages: (i) a 43-40 Ma quartzose limestone and packstone package; (ii) a 39-37 Ma wackestone package with ooze; and (iii) an Upper Eocene fine-grained wackestone package mainly 36.5-35 M...
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Language: | English |
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Online Access: | http://hdl.handle.net/2440/1681 https://doi.org/10.1046/j.1440-0952.2003.00978.x |
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ftunivadelaidedl:oai:digital.library.adelaide.edu.au:2440/1681 2023-05-15T13:45:29+02:00 Middle and Late Eocene Great Australian Bight lithobiostratigraphy and stepwise evolution of the southern Australian continental margin Li, Q. James, N. McGowran, B. 2003 http://hdl.handle.net/2440/1681 https://doi.org/10.1046/j.1440-0952.2003.00978.x en eng Taylor & Francis Ltd. Australian Journal of Earth Sciences, 2003; 50(1):113-128 0812-0099 1440-0952 http://hdl.handle.net/2440/1681 doi:10.1046/j.1440-0952.2003.00978.x Journal article 2003 ftunivadelaidedl https://doi.org/10.1046/j.1440-0952.2003.00978.x 2023-02-05T19:12:21Z Middle to Upper Eocene carbonates recovered at ODP Leg 182 sites from the Great Australian Bight comprise three packages: (i) a 43-40 Ma quartzose limestone and packstone package; (ii) a 39-37 Ma wackestone package with ooze; and (iii) an Upper Eocene fine-grained wackestone package mainly 36.5-35 Ma in age. Bounding these sediment packages are unconformities inferred to have occurred at ca 43, ca 39, ca 37 and ca 34 Ma, coinciding with four major third-order sequence boundaries. Rapid changes in sea-floor spreading probably caused these unconformities, while a stable high sea-level between spreading pulses led to sediment packaging from offshore to coastal basins. The regional sea-level changes in these Middle to Late Eocene times, when glacioeustatic influence was minimal, were mainly driven by plate tectonics. Biofacies indicate a rapid subsidence, faster offshore than nearshore, during the first phase of accelerated sea-floor spreading between Australia and Antarctica around 43 Ma. Most significant environmental changes affecting sedimentation along the southern Australian margin at that time were the influx of warm waters from the Indian Ocean and the initial development of a stratified water mass in the deepening and widening Australo-Antarctic Gulf. The warm (surface) water supported plankton from the subtropics and migratory and endemic larger benthos including foraminifers, while the fertile deeper waters were sites of chert accumulation. The bloom of carbonate-generating bryozoans contributed to widespread carbonate sedimentation that progressed towards the southeastern margin ∼4 million years later. Subsequent carbonate packaging and unconformities, reflecting a stepwise accelerated sea-floor spreading pattern, persisted into the terminal Eocene before the onset of global glaciation. Article in Journal/Newspaper Antarc* Antarctic Antarctica The University of Adelaide: Digital Library Antarctic Indian Australian Journal of Earth Sciences 50 1 113 128 |
institution |
Open Polar |
collection |
The University of Adelaide: Digital Library |
op_collection_id |
ftunivadelaidedl |
language |
English |
description |
Middle to Upper Eocene carbonates recovered at ODP Leg 182 sites from the Great Australian Bight comprise three packages: (i) a 43-40 Ma quartzose limestone and packstone package; (ii) a 39-37 Ma wackestone package with ooze; and (iii) an Upper Eocene fine-grained wackestone package mainly 36.5-35 Ma in age. Bounding these sediment packages are unconformities inferred to have occurred at ca 43, ca 39, ca 37 and ca 34 Ma, coinciding with four major third-order sequence boundaries. Rapid changes in sea-floor spreading probably caused these unconformities, while a stable high sea-level between spreading pulses led to sediment packaging from offshore to coastal basins. The regional sea-level changes in these Middle to Late Eocene times, when glacioeustatic influence was minimal, were mainly driven by plate tectonics. Biofacies indicate a rapid subsidence, faster offshore than nearshore, during the first phase of accelerated sea-floor spreading between Australia and Antarctica around 43 Ma. Most significant environmental changes affecting sedimentation along the southern Australian margin at that time were the influx of warm waters from the Indian Ocean and the initial development of a stratified water mass in the deepening and widening Australo-Antarctic Gulf. The warm (surface) water supported plankton from the subtropics and migratory and endemic larger benthos including foraminifers, while the fertile deeper waters were sites of chert accumulation. The bloom of carbonate-generating bryozoans contributed to widespread carbonate sedimentation that progressed towards the southeastern margin ∼4 million years later. Subsequent carbonate packaging and unconformities, reflecting a stepwise accelerated sea-floor spreading pattern, persisted into the terminal Eocene before the onset of global glaciation. |
format |
Article in Journal/Newspaper |
author |
Li, Q. James, N. McGowran, B. |
spellingShingle |
Li, Q. James, N. McGowran, B. Middle and Late Eocene Great Australian Bight lithobiostratigraphy and stepwise evolution of the southern Australian continental margin |
author_facet |
Li, Q. James, N. McGowran, B. |
author_sort |
Li, Q. |
title |
Middle and Late Eocene Great Australian Bight lithobiostratigraphy and stepwise evolution of the southern Australian continental margin |
title_short |
Middle and Late Eocene Great Australian Bight lithobiostratigraphy and stepwise evolution of the southern Australian continental margin |
title_full |
Middle and Late Eocene Great Australian Bight lithobiostratigraphy and stepwise evolution of the southern Australian continental margin |
title_fullStr |
Middle and Late Eocene Great Australian Bight lithobiostratigraphy and stepwise evolution of the southern Australian continental margin |
title_full_unstemmed |
Middle and Late Eocene Great Australian Bight lithobiostratigraphy and stepwise evolution of the southern Australian continental margin |
title_sort |
middle and late eocene great australian bight lithobiostratigraphy and stepwise evolution of the southern australian continental margin |
publisher |
Taylor & Francis Ltd. |
publishDate |
2003 |
url |
http://hdl.handle.net/2440/1681 https://doi.org/10.1046/j.1440-0952.2003.00978.x |
geographic |
Antarctic Indian |
geographic_facet |
Antarctic Indian |
genre |
Antarc* Antarctic Antarctica |
genre_facet |
Antarc* Antarctic Antarctica |
op_relation |
Australian Journal of Earth Sciences, 2003; 50(1):113-128 0812-0099 1440-0952 http://hdl.handle.net/2440/1681 doi:10.1046/j.1440-0952.2003.00978.x |
op_doi |
https://doi.org/10.1046/j.1440-0952.2003.00978.x |
container_title |
Australian Journal of Earth Sciences |
container_volume |
50 |
container_issue |
1 |
container_start_page |
113 |
op_container_end_page |
128 |
_version_ |
1766225023001952256 |