BIOTIC RESPONSE TO PALEOCEANOGRAPHIC CHANGES IN THE MIDDLE EOCENE OF BLAKE NOSE, WESTERN NORTH ATLANTIC
Geochemical proxy records of sea surface environmental conditions at Blake Nose indicate short-term high amplitude variations. In order to investigate the response of calcareous nannoplankton to these short-term sea-surface environmental changes, we developed a high-resolution Eocene planktonic fora...
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fttexasamuniv:oai:oaktrust.library.tamu.edu:1969.1/ETD-TAMU-2009-05-420 2023-07-16T03:59:58+02:00 BIOTIC RESPONSE TO PALEOCEANOGRAPHIC CHANGES IN THE MIDDLE EOCENE OF BLAKE NOSE, WESTERN NORTH ATLANTIC Okafor, Chioma U. Thomas, Deborah Firth, John Thomas, Olszewski Wade, Bridget Slowey, Niall May 2009 application/pdf https://hdl.handle.net/1969.1/ETD-TAMU-2009-05-420 eng eng https://hdl.handle.net/1969.1/ETD-TAMU-2009-05-420 Nannofossil abundance Book Thesis Electronic Dissertation text 2009 fttexasamuniv 2023-06-27T22:56:03Z Geochemical proxy records of sea surface environmental conditions at Blake Nose indicate short-term high amplitude variations. In order to investigate the response of calcareous nannoplankton to these short-term sea-surface environmental changes, we developed a high-resolution Eocene planktonic foraminifera Mg/Ca record and calcareous nannofossil absolute abundance record for ODP Site 1052 spanning the late middle Eocene (37.85 to 37.45 Ma). These data enable direct comparison of the absolute nannofossil abundance data to geochemical paleoenvironmental proxies (Mg/Ca, ?18O and ?13C) to determine the phytoplankton response to paleoenvironmental change and whether temperature or nutrient levels exerted primary control. The nannofossil absolute abundances were estimated using a combination of the random settling technique (RST) and spiking method (SM), which are two independent methods. Both methods yielded similar and reproducible results. The calculated Mg/Ca paleotemperature record indicates a decrease in SSTs from ~33 to 28�C, while the ?18Osw values calculated from the Mg/Ca paleotemperature also decreased from ~3? at 37.83 Ma to ~2? at 37.6 Ma. The combined trends of the SST and ?18Osw suggest that continental ice did not have a major influence on the climate during the study interval. Variations in the Gulf Stream (e.g. track of proto-Gulf stream, number and transit of eddies, and Gulf Stream related upwelling), may have contributed to the reconstructed sea surface hydrographical changes at Blake Nose. However, overall weakening of the hydrological cycle as global climate transitioned from a greenhouse to an icehouse could be the major factor controlling the hydrographical changes at Blake Nose. Approximately 48 nannofossil taxa were identified in this study. These taxa have been grouped into major, minor and rare taxa based on their abundance in any given sample. Results of the statistical analyses (canonical correspondence analysis CCA, Cluster analysis, and correspondence analysis CA) used to relate the ... Book North Atlantic Planktonic foraminifera Texas A&M University Digital Repository |
institution |
Open Polar |
collection |
Texas A&M University Digital Repository |
op_collection_id |
fttexasamuniv |
language |
English |
topic |
Nannofossil abundance |
spellingShingle |
Nannofossil abundance Okafor, Chioma U. BIOTIC RESPONSE TO PALEOCEANOGRAPHIC CHANGES IN THE MIDDLE EOCENE OF BLAKE NOSE, WESTERN NORTH ATLANTIC |
topic_facet |
Nannofossil abundance |
description |
Geochemical proxy records of sea surface environmental conditions at Blake Nose indicate short-term high amplitude variations. In order to investigate the response of calcareous nannoplankton to these short-term sea-surface environmental changes, we developed a high-resolution Eocene planktonic foraminifera Mg/Ca record and calcareous nannofossil absolute abundance record for ODP Site 1052 spanning the late middle Eocene (37.85 to 37.45 Ma). These data enable direct comparison of the absolute nannofossil abundance data to geochemical paleoenvironmental proxies (Mg/Ca, ?18O and ?13C) to determine the phytoplankton response to paleoenvironmental change and whether temperature or nutrient levels exerted primary control. The nannofossil absolute abundances were estimated using a combination of the random settling technique (RST) and spiking method (SM), which are two independent methods. Both methods yielded similar and reproducible results. The calculated Mg/Ca paleotemperature record indicates a decrease in SSTs from ~33 to 28�C, while the ?18Osw values calculated from the Mg/Ca paleotemperature also decreased from ~3? at 37.83 Ma to ~2? at 37.6 Ma. The combined trends of the SST and ?18Osw suggest that continental ice did not have a major influence on the climate during the study interval. Variations in the Gulf Stream (e.g. track of proto-Gulf stream, number and transit of eddies, and Gulf Stream related upwelling), may have contributed to the reconstructed sea surface hydrographical changes at Blake Nose. However, overall weakening of the hydrological cycle as global climate transitioned from a greenhouse to an icehouse could be the major factor controlling the hydrographical changes at Blake Nose. Approximately 48 nannofossil taxa were identified in this study. These taxa have been grouped into major, minor and rare taxa based on their abundance in any given sample. Results of the statistical analyses (canonical correspondence analysis CCA, Cluster analysis, and correspondence analysis CA) used to relate the ... |
author2 |
Thomas, Deborah Firth, John Thomas, Olszewski Wade, Bridget Slowey, Niall |
format |
Book |
author |
Okafor, Chioma U. |
author_facet |
Okafor, Chioma U. |
author_sort |
Okafor, Chioma U. |
title |
BIOTIC RESPONSE TO PALEOCEANOGRAPHIC CHANGES IN THE MIDDLE EOCENE OF BLAKE NOSE, WESTERN NORTH ATLANTIC |
title_short |
BIOTIC RESPONSE TO PALEOCEANOGRAPHIC CHANGES IN THE MIDDLE EOCENE OF BLAKE NOSE, WESTERN NORTH ATLANTIC |
title_full |
BIOTIC RESPONSE TO PALEOCEANOGRAPHIC CHANGES IN THE MIDDLE EOCENE OF BLAKE NOSE, WESTERN NORTH ATLANTIC |
title_fullStr |
BIOTIC RESPONSE TO PALEOCEANOGRAPHIC CHANGES IN THE MIDDLE EOCENE OF BLAKE NOSE, WESTERN NORTH ATLANTIC |
title_full_unstemmed |
BIOTIC RESPONSE TO PALEOCEANOGRAPHIC CHANGES IN THE MIDDLE EOCENE OF BLAKE NOSE, WESTERN NORTH ATLANTIC |
title_sort |
biotic response to paleoceanographic changes in the middle eocene of blake nose, western north atlantic |
publishDate |
2009 |
url |
https://hdl.handle.net/1969.1/ETD-TAMU-2009-05-420 |
genre |
North Atlantic Planktonic foraminifera |
genre_facet |
North Atlantic Planktonic foraminifera |
op_relation |
https://hdl.handle.net/1969.1/ETD-TAMU-2009-05-420 |
_version_ |
1771548376306810880 |