Late Eocene–early Miocene evolution of the southern Australian subtropical front: a marine palynological approach
mprovements in our capability to reconstruct ancient surface-ocean conditions based on organic-walled dinoflagellate cyst (dinocyst) assemblages from the Southern Ocean provide an opportunity to better establish past position, strength and oceanography of the subtropical front (STF). Here, we aim to...
Published in: | Journal of Micropalaeontology |
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Language: | English |
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2021
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Online Access: | https://www.vliz.be/imisdocs/publications/26/369126.pdf |
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ftnioz:oai:imis.nioz.nl:347205 2023-05-15T13:47:57+02:00 Late Eocene–early Miocene evolution of the southern Australian subtropical front: a marine palynological approach Hoem, F.S. Sauermilch, I. Hou, S. Brinkhuis, H. Sangiorgi, F. Bijl, P.K. 2021 application/pdf https://www.vliz.be/imisdocs/publications/26/369126.pdf en eng info:eu-repo/semantics/altIdentifier/wos/000714348100001 info:eu-repo/semantics/altIdentifier/doi/doi.org/10.5194/jm-40-175-2021 https://www.vliz.be/imisdocs/publications/26/369126.pdf info:eu-repo/semantics/openAccess %3Ci%3EJ.+Micropalaeontol.+40%282%29%3C%2Fi%3E%3A+175-193.+%3Ca+href%3D%22https%3A%2F%2Fdx.doi.org%2F10.5194%2Fjm-40-175-2021%22+target%3D%22_blank%22%3Ehttps%3A%2F%2Fdx.doi.org%2F10.5194%2Fjm-40-175-2021%3C%2Fa%3E info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 2021 ftnioz https://doi.org/10.5194/jm-40-175-2021 2022-05-01T14:15:45Z mprovements in our capability to reconstruct ancient surface-ocean conditions based on organic-walled dinoflagellate cyst (dinocyst) assemblages from the Southern Ocean provide an opportunity to better establish past position, strength and oceanography of the subtropical front (STF). Here, we aim to reconstruct the late Eocene to early Miocene (37–20 Ma) depositional and palaeoceanographic history of the STF in the context of the evolving Tasmanian Gateway as well as the potential influence of Antarctic circumpolar flow and intense waxing and waning of ice. We approach this by combining information from seismic lines (revisiting existing data and generating new marine palynological data from Ocean Drilling Program (ODP) Hole 1168A) in the western Tasmanian continental slope. We apply improved taxonomic insights and palaeoecological models to reconstruct the sea surface palaeoenvironmental evolution. Late Eocene–early Oligocene (37–30.5 Ma) assemblages show a progressive transition from dominant terrestrial palynomorphs and inner-neritic dinocyst taxa as well as cysts produced by heterotrophic dinoflagellates to predominantly outer-neritic/oceanic autotrophic taxa. This transition reflects the progressive deepening of the western Tasmanian continental margin, an interpretation supported by our new seismic investigations. The dominance of autotrophic species like Spiniferites spp. and Operculodinium spp. reflects relatively oligotrophic conditions, like those of regions north of the modern-day STF. The increased abundance in the earliest Miocene of Nematosphaeropsis labyrinthus , typical for modern subantarctic zone (frontal) conditions, indicates a cooling and/or closer proximity of the STF to the site . The absence of major shifts in dinocyst assemblages contrasts with other records in the region and suggests that small changes in surface oceanographic conditions occurred during the Oligocene. Despite the relatively southerly (63–55∘ S) location of Site 1168, the rather stable oceanographic conditions reflect the continued influence of the proto-Leeuwin Current along the southern Australian coast as Australia continued to drift northward. The relatively “warm” dinocyst assemblages at ODP Site 1168, compared with the cold assemblages at Antarctic Integrated Ocean Drilling Program (IODP) Site U1356, testify to the establishment of a pronounced latitudinal temperature gradient in the Oligocene Southern Ocean. Article in Journal/Newspaper Antarc* Antarctic Southern Ocean NIOZ Repository (Royal Netherlands Institute for Sea Research) Antarctic Southern Ocean Journal of Micropalaeontology 40 2 175 193 |
institution |
Open Polar |
collection |
NIOZ Repository (Royal Netherlands Institute for Sea Research) |
op_collection_id |
ftnioz |
language |
English |
description |
mprovements in our capability to reconstruct ancient surface-ocean conditions based on organic-walled dinoflagellate cyst (dinocyst) assemblages from the Southern Ocean provide an opportunity to better establish past position, strength and oceanography of the subtropical front (STF). Here, we aim to reconstruct the late Eocene to early Miocene (37–20 Ma) depositional and palaeoceanographic history of the STF in the context of the evolving Tasmanian Gateway as well as the potential influence of Antarctic circumpolar flow and intense waxing and waning of ice. We approach this by combining information from seismic lines (revisiting existing data and generating new marine palynological data from Ocean Drilling Program (ODP) Hole 1168A) in the western Tasmanian continental slope. We apply improved taxonomic insights and palaeoecological models to reconstruct the sea surface palaeoenvironmental evolution. Late Eocene–early Oligocene (37–30.5 Ma) assemblages show a progressive transition from dominant terrestrial palynomorphs and inner-neritic dinocyst taxa as well as cysts produced by heterotrophic dinoflagellates to predominantly outer-neritic/oceanic autotrophic taxa. This transition reflects the progressive deepening of the western Tasmanian continental margin, an interpretation supported by our new seismic investigations. The dominance of autotrophic species like Spiniferites spp. and Operculodinium spp. reflects relatively oligotrophic conditions, like those of regions north of the modern-day STF. The increased abundance in the earliest Miocene of Nematosphaeropsis labyrinthus , typical for modern subantarctic zone (frontal) conditions, indicates a cooling and/or closer proximity of the STF to the site . The absence of major shifts in dinocyst assemblages contrasts with other records in the region and suggests that small changes in surface oceanographic conditions occurred during the Oligocene. Despite the relatively southerly (63–55∘ S) location of Site 1168, the rather stable oceanographic conditions reflect the continued influence of the proto-Leeuwin Current along the southern Australian coast as Australia continued to drift northward. The relatively “warm” dinocyst assemblages at ODP Site 1168, compared with the cold assemblages at Antarctic Integrated Ocean Drilling Program (IODP) Site U1356, testify to the establishment of a pronounced latitudinal temperature gradient in the Oligocene Southern Ocean. |
format |
Article in Journal/Newspaper |
author |
Hoem, F.S. Sauermilch, I. Hou, S. Brinkhuis, H. Sangiorgi, F. Bijl, P.K. |
spellingShingle |
Hoem, F.S. Sauermilch, I. Hou, S. Brinkhuis, H. Sangiorgi, F. Bijl, P.K. Late Eocene–early Miocene evolution of the southern Australian subtropical front: a marine palynological approach |
author_facet |
Hoem, F.S. Sauermilch, I. Hou, S. Brinkhuis, H. Sangiorgi, F. Bijl, P.K. |
author_sort |
Hoem, F.S. |
title |
Late Eocene–early Miocene evolution of the southern Australian subtropical front: a marine palynological approach |
title_short |
Late Eocene–early Miocene evolution of the southern Australian subtropical front: a marine palynological approach |
title_full |
Late Eocene–early Miocene evolution of the southern Australian subtropical front: a marine palynological approach |
title_fullStr |
Late Eocene–early Miocene evolution of the southern Australian subtropical front: a marine palynological approach |
title_full_unstemmed |
Late Eocene–early Miocene evolution of the southern Australian subtropical front: a marine palynological approach |
title_sort |
late eocene–early miocene evolution of the southern australian subtropical front: a marine palynological approach |
publishDate |
2021 |
url |
https://www.vliz.be/imisdocs/publications/26/369126.pdf |
geographic |
Antarctic Southern Ocean |
geographic_facet |
Antarctic Southern Ocean |
genre |
Antarc* Antarctic Southern Ocean |
genre_facet |
Antarc* Antarctic Southern Ocean |
op_source |
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op_relation |
info:eu-repo/semantics/altIdentifier/wos/000714348100001 info:eu-repo/semantics/altIdentifier/doi/doi.org/10.5194/jm-40-175-2021 https://www.vliz.be/imisdocs/publications/26/369126.pdf |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/jm-40-175-2021 |
container_title |
Journal of Micropalaeontology |
container_volume |
40 |
container_issue |
2 |
container_start_page |
175 |
op_container_end_page |
193 |
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1766248061356474368 |