Deciphering the state of the late Miocene to early Pliocene equatorial Pacific
A.J. Drury was funded by a Janet Watson studentship from Imperial College London. The late Miocene-early Pliocene was a time of global cooling and the development of modern meridional thermal gradients. Equatorial Pacific sea surface conditions potentially played an important role in this global cli...
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ftstandrewserep:oai:research-repository.st-andrews.ac.uk:10023/16003 2024-09-15T17:48:37+00:00 Deciphering the state of the late Miocene to early Pliocene equatorial Pacific Drury, A. J. Lee, G. P. Gray, W. R. Lyle, M. Westerhold, T. Shevenell, A. E. John, C. M. University of St Andrews.School of Earth & Environmental Sciences 2018-09-11 18 4735802 application/pdf https://hdl.handle.net/10023/16003 https://doi.org/10.1002/2017PA003245 eng eng Paleoceanography and Paleoclimatology 252215512 d97e7c56-056c-40ba-b3ae-854b9c33faed 85045530262 000430991200001 Drury , A J , Lee , G P , Gray , W R , Lyle , M , Westerhold , T , Shevenell , A E & John , C M 2018 , ' Deciphering the state of the late Miocene to early Pliocene equatorial Pacific ' , Paleoceanography and Paleoclimatology , vol. Early View . https://doi.org/10.1002/2017PA003245 2572-4525 Bibtex: urn:ef60a55192d15391c70a6b26fa9b616b https://hdl.handle.net/10023/16003 doi:10.1002/2017PA003245 © 2018 American Geophysical Union. All Rights Reserved. This work is made available online in accordance with the publisher’s policies. This is the final published version of the work, which was originally published at: https://doi.org/10.1002/2017PA003245 Planktic foraminifera stable isotope records Late Miocene to early Pliocene Equatorial Pacific mean state Surface ocean conditions Biogenic bloom Mg/Ca sea surface temperature GE Environmental Sciences GC Oceanography DAS SDG 13 - Climate Action GE GC Journal article 2018 ftstandrewserep https://doi.org/10.1002/2017PA003245 2024-08-28T00:12:18Z A.J. Drury was funded by a Janet Watson studentship from Imperial College London. The late Miocene-early Pliocene was a time of global cooling and the development of modern meridional thermal gradients. Equatorial Pacific sea surface conditions potentially played an important role in this global climate transition, but their evolution is poorly understood. Here, we present the first continuous late Miocene-early Pliocene (8.0-4.4 Ma) planktic foraminiferal stable isotope records from eastern equatorial Pacific Integrated Ocean Drilling Program Site U1338, with a new astrochronology spanning 8.0-3.5 Ma. Mg/Ca analyses on surface dwelling foraminifera Trilobatus sacculifer from carefully selected samples suggest mean sea-surface-temperatures (SSTs) are ~27.8±1.1°C (1σ) between 6.4-5.5 Ma. The planktic foraminiferal δ18O record implies a 2°C cooling between 7.2-6.1 Ma and an up to 3°C warming between 6.1-4.4 Ma, consistent with observed tropical alkenone paleo-SSTs. Diverging fine-fraction-to-foraminiferal δ13C gradients likely suggest increased upwelling from 7.1-6.0 and 5.8-4.6 Ma, concurrent with the globally recognized late Miocene Biogenic Bloom. This study shows that both warm and asymmetric mean states occurred in the equatorial Pacific during the late Miocene-early Pliocene. Between 8.0-6.5 and 5.2-4.4 Ma, low east-west δ18O and SST gradients and generally warm conditions prevailed. However, an asymmetric mean climate state developed between 6.5-5.7 Ma, with larger east-west δ18O and SST gradients and eastern equatorial Pacific cooling. The asymmetric mean state suggests stronger trade winds developed, driven by increased meridional thermal gradients associated with global cooling and declining atmospheric pCO2 concentrations. These oscillations in equatorial Pacific mean state are reinforced by Antarctic cryosphere expansion and related changes in oceanic gateways (e.g., Central American Seaway/Indonesian Throughflow restriction). Peer reviewed Article in Journal/Newspaper Antarc* Antarctic University of St Andrews: Digital Research Repository Paleoceanography and Paleoclimatology 33 3 246 263 |
institution |
Open Polar |
collection |
University of St Andrews: Digital Research Repository |
op_collection_id |
ftstandrewserep |
language |
English |
topic |
Planktic foraminifera stable isotope records Late Miocene to early Pliocene Equatorial Pacific mean state Surface ocean conditions Biogenic bloom Mg/Ca sea surface temperature GE Environmental Sciences GC Oceanography DAS SDG 13 - Climate Action GE GC |
spellingShingle |
Planktic foraminifera stable isotope records Late Miocene to early Pliocene Equatorial Pacific mean state Surface ocean conditions Biogenic bloom Mg/Ca sea surface temperature GE Environmental Sciences GC Oceanography DAS SDG 13 - Climate Action GE GC Drury, A. J. Lee, G. P. Gray, W. R. Lyle, M. Westerhold, T. Shevenell, A. E. John, C. M. Deciphering the state of the late Miocene to early Pliocene equatorial Pacific |
topic_facet |
Planktic foraminifera stable isotope records Late Miocene to early Pliocene Equatorial Pacific mean state Surface ocean conditions Biogenic bloom Mg/Ca sea surface temperature GE Environmental Sciences GC Oceanography DAS SDG 13 - Climate Action GE GC |
description |
A.J. Drury was funded by a Janet Watson studentship from Imperial College London. The late Miocene-early Pliocene was a time of global cooling and the development of modern meridional thermal gradients. Equatorial Pacific sea surface conditions potentially played an important role in this global climate transition, but their evolution is poorly understood. Here, we present the first continuous late Miocene-early Pliocene (8.0-4.4 Ma) planktic foraminiferal stable isotope records from eastern equatorial Pacific Integrated Ocean Drilling Program Site U1338, with a new astrochronology spanning 8.0-3.5 Ma. Mg/Ca analyses on surface dwelling foraminifera Trilobatus sacculifer from carefully selected samples suggest mean sea-surface-temperatures (SSTs) are ~27.8±1.1°C (1σ) between 6.4-5.5 Ma. The planktic foraminiferal δ18O record implies a 2°C cooling between 7.2-6.1 Ma and an up to 3°C warming between 6.1-4.4 Ma, consistent with observed tropical alkenone paleo-SSTs. Diverging fine-fraction-to-foraminiferal δ13C gradients likely suggest increased upwelling from 7.1-6.0 and 5.8-4.6 Ma, concurrent with the globally recognized late Miocene Biogenic Bloom. This study shows that both warm and asymmetric mean states occurred in the equatorial Pacific during the late Miocene-early Pliocene. Between 8.0-6.5 and 5.2-4.4 Ma, low east-west δ18O and SST gradients and generally warm conditions prevailed. However, an asymmetric mean climate state developed between 6.5-5.7 Ma, with larger east-west δ18O and SST gradients and eastern equatorial Pacific cooling. The asymmetric mean state suggests stronger trade winds developed, driven by increased meridional thermal gradients associated with global cooling and declining atmospheric pCO2 concentrations. These oscillations in equatorial Pacific mean state are reinforced by Antarctic cryosphere expansion and related changes in oceanic gateways (e.g., Central American Seaway/Indonesian Throughflow restriction). Peer reviewed |
author2 |
University of St Andrews.School of Earth & Environmental Sciences |
format |
Article in Journal/Newspaper |
author |
Drury, A. J. Lee, G. P. Gray, W. R. Lyle, M. Westerhold, T. Shevenell, A. E. John, C. M. |
author_facet |
Drury, A. J. Lee, G. P. Gray, W. R. Lyle, M. Westerhold, T. Shevenell, A. E. John, C. M. |
author_sort |
Drury, A. J. |
title |
Deciphering the state of the late Miocene to early Pliocene equatorial Pacific |
title_short |
Deciphering the state of the late Miocene to early Pliocene equatorial Pacific |
title_full |
Deciphering the state of the late Miocene to early Pliocene equatorial Pacific |
title_fullStr |
Deciphering the state of the late Miocene to early Pliocene equatorial Pacific |
title_full_unstemmed |
Deciphering the state of the late Miocene to early Pliocene equatorial Pacific |
title_sort |
deciphering the state of the late miocene to early pliocene equatorial pacific |
publishDate |
2018 |
url |
https://hdl.handle.net/10023/16003 https://doi.org/10.1002/2017PA003245 |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_relation |
Paleoceanography and Paleoclimatology 252215512 d97e7c56-056c-40ba-b3ae-854b9c33faed 85045530262 000430991200001 Drury , A J , Lee , G P , Gray , W R , Lyle , M , Westerhold , T , Shevenell , A E & John , C M 2018 , ' Deciphering the state of the late Miocene to early Pliocene equatorial Pacific ' , Paleoceanography and Paleoclimatology , vol. Early View . https://doi.org/10.1002/2017PA003245 2572-4525 Bibtex: urn:ef60a55192d15391c70a6b26fa9b616b https://hdl.handle.net/10023/16003 doi:10.1002/2017PA003245 |
op_rights |
© 2018 American Geophysical Union. All Rights Reserved. This work is made available online in accordance with the publisher’s policies. This is the final published version of the work, which was originally published at: https://doi.org/10.1002/2017PA003245 |
op_doi |
https://doi.org/10.1002/2017PA003245 |
container_title |
Paleoceanography and Paleoclimatology |
container_volume |
33 |
container_issue |
3 |
container_start_page |
246 |
op_container_end_page |
263 |
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1810290062431092736 |