Expansion and diversification of high-latitude radiolarian assemblages in the late Eocene linked to a cooling event in the southwest Pacific
The long-term cooling trend from middle to late Eocene was punctuated by several large-scale climate perturbations that culminated in a shift to "icehouse" climates at the Eocene–Oligocene transition. We present radiolarian micro-fossil assemblage and foraminiferal oxygen and carbon stable...
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00014602 2023-05-15T13:41:02+02:00 Expansion and diversification of high-latitude radiolarian assemblages in the late Eocene linked to a cooling event in the southwest Pacific Pascher, K. M. Hollis, C. J. Bohaty, S. M. Cortese, G. McKay, R. M. Seebeck, H. Suzuki, N. Chiba, K. 2015-12 electronic https://doi.org/10.5194/cp-11-1599-2015 https://noa.gwlb.de/receive/cop_mods_00014602 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00014557/cp-11-1599-2015.pdf https://cp.copernicus.org/articles/11/1599/2015/cp-11-1599-2015.pdf eng eng Copernicus Publications Climate of the Past -- http://www.copernicus.org/EGU/cp/cp/published_papers.html -- http://www.bibliothek.uni-regensburg.de/ezeit/?2217985 -- 1814-9332 https://doi.org/10.5194/cp-11-1599-2015 https://noa.gwlb.de/receive/cop_mods_00014602 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00014557/cp-11-1599-2015.pdf https://cp.copernicus.org/articles/11/1599/2015/cp-11-1599-2015.pdf uneingeschränkt info:eu-repo/semantics/openAccess article Verlagsveröffentlichung article Text doc-type:article 2015 ftnonlinearchiv https://doi.org/10.5194/cp-11-1599-2015 2022-02-08T22:55:00Z The long-term cooling trend from middle to late Eocene was punctuated by several large-scale climate perturbations that culminated in a shift to "icehouse" climates at the Eocene–Oligocene transition. We present radiolarian micro-fossil assemblage and foraminiferal oxygen and carbon stable isotope data from Deep Sea Drilling Project (DSDP) sites 277, 280, 281, and 283 and Ocean Drilling Project (ODP) Site 1172 to identify significant oceanographic changes in the southwest Pacific through this climate transition (~ 40–30 Ma). We find that the Middle Eocene Climatic Optimum at ~ 40 Ma, which is truncated but identified by a negative shift in foraminiferal δ18O values at Site 277, is associated with a small increase in radiolarian taxa with low-latitude affinities (5 % of total fauna). In the early late Eocene at ~ 37 Ma, a positive oxygen isotope shift at Site 277 is correlated with the Priabonian Oxygen Isotope Maximum (PrOM). Radiolarian abundance, diversity, and preservation increase within this cooling event at Site 277 at the same time as diatom abundance. A negative δ18O excursion above the PrOM is correlated with a late Eocene warming event (~ 36.4 Ma). Radiolarian abundance and diversity decline within this event and taxa with low-latitude affinities reappear. Apart from this short-lived warming event, the PrOM and latest Eocene radiolarian assemblages are characterised by abundant high-latitude taxa. High-latitude taxa are also abundant during the late Eocene and early Oligocene (~ 38–30 Ma) at DSDP sites 280, 281, 283 and 1172 and are associated with very high diatom abundance. We therefore infer a northward expansion of high-latitude radiolarian taxa onto the Campbell Plateau in the latest Eocene. In the early Oligocene there is an overall decrease in radiolarian abundance and diversity at Site 277, and diatoms are scarce. These data indicate that, once the Antarctic Circumpolar Current was established in the early Oligocene (~ 30 Ma), a frontal system similar to present day developed, with nutrient-depleted Subantarctic waters bathing the area around DSDP Site 277, resulting in a more restricted siliceous plankton assemblage. Article in Journal/Newspaper Antarc* Antarctic Niedersächsisches Online-Archiv NOA Antarctic Campbell Plateau ENVELOPE(171.000,171.000,-50.667,-50.667) Pacific The Antarctic Climate of the Past 11 12 1599 1620 |
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Niedersächsisches Online-Archiv NOA |
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ftnonlinearchiv |
language |
English |
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article Verlagsveröffentlichung |
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article Verlagsveröffentlichung Pascher, K. M. Hollis, C. J. Bohaty, S. M. Cortese, G. McKay, R. M. Seebeck, H. Suzuki, N. Chiba, K. Expansion and diversification of high-latitude radiolarian assemblages in the late Eocene linked to a cooling event in the southwest Pacific |
topic_facet |
article Verlagsveröffentlichung |
description |
The long-term cooling trend from middle to late Eocene was punctuated by several large-scale climate perturbations that culminated in a shift to "icehouse" climates at the Eocene–Oligocene transition. We present radiolarian micro-fossil assemblage and foraminiferal oxygen and carbon stable isotope data from Deep Sea Drilling Project (DSDP) sites 277, 280, 281, and 283 and Ocean Drilling Project (ODP) Site 1172 to identify significant oceanographic changes in the southwest Pacific through this climate transition (~ 40–30 Ma). We find that the Middle Eocene Climatic Optimum at ~ 40 Ma, which is truncated but identified by a negative shift in foraminiferal δ18O values at Site 277, is associated with a small increase in radiolarian taxa with low-latitude affinities (5 % of total fauna). In the early late Eocene at ~ 37 Ma, a positive oxygen isotope shift at Site 277 is correlated with the Priabonian Oxygen Isotope Maximum (PrOM). Radiolarian abundance, diversity, and preservation increase within this cooling event at Site 277 at the same time as diatom abundance. A negative δ18O excursion above the PrOM is correlated with a late Eocene warming event (~ 36.4 Ma). Radiolarian abundance and diversity decline within this event and taxa with low-latitude affinities reappear. Apart from this short-lived warming event, the PrOM and latest Eocene radiolarian assemblages are characterised by abundant high-latitude taxa. High-latitude taxa are also abundant during the late Eocene and early Oligocene (~ 38–30 Ma) at DSDP sites 280, 281, 283 and 1172 and are associated with very high diatom abundance. We therefore infer a northward expansion of high-latitude radiolarian taxa onto the Campbell Plateau in the latest Eocene. In the early Oligocene there is an overall decrease in radiolarian abundance and diversity at Site 277, and diatoms are scarce. These data indicate that, once the Antarctic Circumpolar Current was established in the early Oligocene (~ 30 Ma), a frontal system similar to present day developed, with nutrient-depleted Subantarctic waters bathing the area around DSDP Site 277, resulting in a more restricted siliceous plankton assemblage. |
format |
Article in Journal/Newspaper |
author |
Pascher, K. M. Hollis, C. J. Bohaty, S. M. Cortese, G. McKay, R. M. Seebeck, H. Suzuki, N. Chiba, K. |
author_facet |
Pascher, K. M. Hollis, C. J. Bohaty, S. M. Cortese, G. McKay, R. M. Seebeck, H. Suzuki, N. Chiba, K. |
author_sort |
Pascher, K. M. |
title |
Expansion and diversification of high-latitude radiolarian assemblages in the late Eocene linked to a cooling event in the southwest Pacific |
title_short |
Expansion and diversification of high-latitude radiolarian assemblages in the late Eocene linked to a cooling event in the southwest Pacific |
title_full |
Expansion and diversification of high-latitude radiolarian assemblages in the late Eocene linked to a cooling event in the southwest Pacific |
title_fullStr |
Expansion and diversification of high-latitude radiolarian assemblages in the late Eocene linked to a cooling event in the southwest Pacific |
title_full_unstemmed |
Expansion and diversification of high-latitude radiolarian assemblages in the late Eocene linked to a cooling event in the southwest Pacific |
title_sort |
expansion and diversification of high-latitude radiolarian assemblages in the late eocene linked to a cooling event in the southwest pacific |
publisher |
Copernicus Publications |
publishDate |
2015 |
url |
https://doi.org/10.5194/cp-11-1599-2015 https://noa.gwlb.de/receive/cop_mods_00014602 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00014557/cp-11-1599-2015.pdf https://cp.copernicus.org/articles/11/1599/2015/cp-11-1599-2015.pdf |
long_lat |
ENVELOPE(171.000,171.000,-50.667,-50.667) |
geographic |
Antarctic Campbell Plateau Pacific The Antarctic |
geographic_facet |
Antarctic Campbell Plateau Pacific The Antarctic |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_relation |
Climate of the Past -- http://www.copernicus.org/EGU/cp/cp/published_papers.html -- http://www.bibliothek.uni-regensburg.de/ezeit/?2217985 -- 1814-9332 https://doi.org/10.5194/cp-11-1599-2015 https://noa.gwlb.de/receive/cop_mods_00014602 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00014557/cp-11-1599-2015.pdf https://cp.copernicus.org/articles/11/1599/2015/cp-11-1599-2015.pdf |
op_rights |
uneingeschränkt info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/cp-11-1599-2015 |
container_title |
Climate of the Past |
container_volume |
11 |
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12 |
container_start_page |
1599 |
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1620 |
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1766145048781520896 |