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dc.contributor.authorDrury, A. J.
dc.contributor.authorLee, G. P.
dc.contributor.authorGray, W. R.
dc.contributor.authorLyle, M.
dc.contributor.authorWesterhold, T.
dc.contributor.authorShevenell, A. E.
dc.contributor.authorJohn, C. M.
dc.identifier.citationDrury , 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 .
dc.identifier.otherPURE: 252215512
dc.identifier.otherPURE UUID: d97e7c56-056c-40ba-b3ae-854b9c33faed
dc.identifier.otherBibtex: urn:ef60a55192d15391c70a6b26fa9b616b
dc.identifier.otherScopus: 85045530262
dc.identifier.otherWOS: 000430991200001
dc.descriptionA.J. Drury was funded by a Janet Watson studentship from Imperial College London.en
dc.description.abstractThe 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).
dc.relation.ispartofPaleoceanography and Paleoclimatologyen
dc.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:
dc.subjectPlanktic foraminifera stable isotope recordsen
dc.subjectLate Miocene to early Plioceneen
dc.subjectEquatorial Pacific mean stateen
dc.subjectSurface ocean conditionsen
dc.subjectBiogenic bloomen
dc.subjectMg/Ca sea surface temperatureen
dc.subjectGE Environmental Sciencesen
dc.subjectGC Oceanographyen
dc.titleDeciphering the state of the late Miocene to early Pliocene equatorial Pacificen
dc.typeJournal articleen
dc.description.versionPublisher PDFen
dc.contributor.institutionUniversity of St Andrews.School of Earth & Environmental Sciencesen
dc.description.statusPeer revieweden

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