Evaluating climatic response to external radiative forcing during the late Miocene to early Pliocene: New perspectives from eastern equatorial Pacific (IODP U1338) and North Atlantic (ODP 982) locations

Drury, Anna Joy; John, Cédric M.; Shevenell, A.

doi:10.1002/2015pa002881

Cited by 44 publications

(109 citation statements)

References 92 publications

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“…We generated the first continuous T . sacculifer δ 18 O record spanning the late Miocene to early Pliocene and combined these records with published U k’ 37 and benthic δ 18 O records (Drury et al, ; Rousselle et al, ) to reconstruct the SST evolution in the eastern equatorial Pacific between 8.0 and 4.4 Ma. We then assessed eastern equatorial Pacific Ocean productivity and upwelling by comparing planktic and benthic foraminiferal, and fine fraction (<63 μm) δ 13 C records (Drury et al, ; Reghellin et al, ).…”

Section: Introductionmentioning

confidence: 99%

Deciphering the State of the Late Miocene to Early Pliocene Equatorial Pacific

Drury

Lee

Gray

et al. 2018

Paleoceanog and Paleoclimatol

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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 that mean sea surface temperatures (SSTs) are ~27.8 ± 1.1°C (1σ) between 6.4 and 5.5 Ma. The planktic foraminiferal δ18O record implies a 2°C cooling between 7.2 and 6.1 Ma and an up to 3°C warming between 6.1 and 4.4 Ma, consistent with observed tropical alkenone paleo‐SSTs. Diverging fine‐fraction‐to‐foraminiferal δ13C gradients likely suggest increased upwelling between 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 and 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).

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Section: Introductionmentioning

confidence: 99%

Deciphering the State of the Late Miocene to Early Pliocene Equatorial Pacific

Drury

Lee

Gray

et al. 2018

Paleoceanog and Paleoclimatol

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“…As such, it is frequently used as a North Atlantic end member to investigate past deep-sea circulation (Hodell et al, 2001;Bickert et 30 al., 2004;Hodell and Venz-Curtis, 2006;Khélifi et al, 2014;Drury et al, 2016). Additionally it reflects a crucial link to tie regional records of the enclosed Mediterranean basin, such as those from Ain el Beida and Salé Briqueterie to the global signal preserved more strongly in deep-sea sediments (Hodell et al, 1994;Hodell et al, 2001;van der Laan et al, 2005; cycles may be missing at this location.…”

Section: Integrating the Mediterranean And North Atlanticmentioning

confidence: 99%

“…New cycles were identified, which correlate well with isotope records from the Mediterranean and equatorial Atlantic. Past attempts have been made to extend the Marine Isotope Stage (MIS) identification scheme first developed by Shackleton et al (1995) into the late Miocene (van der Laan et al, 2005;Drury et al, 2016). The identification of the new cycles at Site 982 highlights the need for a redefinition of the current MIS scheme for this interval.…”

Section: Integrating the Mediterranean And North Atlanticmentioning

confidence: 99%

“…The identification of the new cycles at Site 982 highlights the need for a redefinition of the current MIS scheme for this interval. Considering the number of high-resolution, robust 10 benthic foraminiferal stratigraphies that now exist for the latest Miocene (Vidal et al, 2002;Bickert et al, 2004;Westerhold et al, 2005;Drury et al, 2016;Drury et al, 2017), a redefinition of late Miocene MIS should soon be attempted, following the global approach applied for the Pliocene by Lisiecki and Raymo (2005).…”

Section: Integrating the Mediterranean And North Atlanticmentioning

confidence: 99%

“…Palaeoclimate records generated at this location have been fundamental to improving our understanding of climate for the past 12 Ma (Venz et al, 1999;Hodell et al, 2001;Venz and Hodell, 2002;Lisiecki and Raymo, 2005;Hodell and Venz-5 Curtis, 2006;Lawrence et al, 2009;Bolton et al, 2011;Khélifi et al, 2014;Herbert et al, 2016). In particular, the late Miocene benthic stable isotope stratigraphy and astrochronology (Hodell et al, 2001) has been used as the basic stratigraphy and/or age model for a wide range of studies (Bickert et al, 2004;Hodell and Venz-Curtis, 2006;Drury et al, 2016;Herbert et al, 2016;Kontakiotis et al, 2016;De Vleeschouwer et al, 2017). However, there is an ongoing debate about the presence of potential stratigraphic issues in the Pliocene successions of Site 982 (Khelifi et al, 2012;Lawrence et al, 2013) and 10 concerns exist that individual cycles may be missing from the late Miocene isotope stratigraphy (Bickert et al, 2004;van der Laan et al, 2005;van der Laan et al, 2012); however, these concerns have not yet been resolved.…”

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confidence: 99%

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Reinforcing the North Atlantic backbone: revision and extension of the composite splice at ODP Site 982

Drury¹,

Westerhold²,

Hodell³

et al. 2017

Preprint

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Abstract. Ocean Drilling Programme (ODP) Site 982 represents a key location for understanding the evolution of climate in the North Atlantic over the past 12 Ma. However, concerns exist about the validity and robustness of the underlying stratigraphy and astrochronology, which currently limits the adequacy of this site for high-resolution climate studies. To resolve this uncertainty, we verify and extend the early Pliocene to late Miocene shipboard composite splice at Site 982 10 using high-resolution XRF core scanning data and establish a robust high-resolution stable isotope stratigraphy and astrochronology between 4.5 and 8.

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Exploring the potential of clumped isotope thermometry on coccolith‐rich sediments as a sea surface temperature proxy

Drury

John

2016

Geochem Geophys Geosyst

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Understanding past changes in sea surface temperatures (SSTs) is crucial; however, existing proxies for reconstructing past SSTs are hindered by unknown ancient seawater composition (foraminiferal Mg/Ca and d 18 O) or reflect subsurface temperatures (TEX 86 ) or have a limited applicable temperature range (U k' 37 ). We examine clumped isotope (D 47 ) thermometry to fossil coccolith-rich material as an SST proxy, as clumped isotopes are independent of original seawater composition and applicable to a wide temperature range and coccolithophores are widespread and dissolution resistant. The D 47 -derived temperatures from <63, <20, <10, and 2-5 lm size fractions of two equatorial Pacific late Miocene-early Pliocene sediment samples (c1; c2) range between $18 and 298C, with c1 temperatures consistently above c2. Removing the >63 lm fraction removes most nonmixed layer components; however, the D 47 -derived temperatures display an unexpected slight decreasing trend with decreasing size fraction. This unexpected trend could partly arise because larger coccoliths (5-12 lm) are removed during the size fraction separation process. The c1 and <63 lm c2 D 47 -derived temperatures are comparable to concurrent U k' 37 SSTs. The <20, <10, and 2-5 lm c2 D 47 -derived temperatures are consistently cooler than expected. The D 47 -U k' 37 temperature offset is probably caused by abiotic/diagenetic calcite present in the c2 2-5 lm fraction ($53% by area), which potentially precipitated at bottom water temperatures of $68C. Our results indicate that clumped isotopes on coccolith-rich sediment fractions have potential as an SST proxy, particularly in tropical regions, providing that careful investigation of the appropriate size fraction for the region and time scale is undertaken.

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Evaluating climatic response to external radiative forcing during the late Miocene to early Pliocene: New perspectives from eastern equatorial Pacific (IODP U1338) and North Atlantic (ODP 982) locations

Cited by 44 publications

References 92 publications

Deciphering the State of the Late Miocene to Early Pliocene Equatorial Pacific

Deciphering the State of the Late Miocene to Early Pliocene Equatorial Pacific

Reinforcing the North Atlantic backbone: revision and extension of the composite splice at ODP Site 982

Exploring the potential of clumped isotope thermometry on coccolith‐rich sediments as a sea surface temperature proxy

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