Antarctic glacio-eustatic contributions to late Miocene Mediterranean desiccation and reflooding

Ohneiser, Christian; Florindo, Fabio; Stocchi, Paolo; Roberts, Andrew P.; DeConto, Robert M.; Pollard, David

doi:10.1038/ncomms9765

Cited by 60 publications

(55 citation statements)

References 69 publications

(117 reference statements)

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“…The development of the asymmetric E-W gradient suggests that the EUC and PCC and the development of the (proto-)EECT first occurred by~6.5 Ma, which is earlier than previously suggested (4.8-4.0 Ma) (Rousselle et al, 2013). Although there is some coincident evidence for increased benthic δ 18 O and cryosphere expansion Ohneiser et al, 2015), our results strongly suggest that the late Miocene experienced significant reorganizations of ocean circulation and climate without large corresponding changes in polar ice sheets. A major reorganization without greatly increased polar ice sheets could indicate that the equatorial Pacific changes were also partly driven by extended sea ice conditions in the southern hemisphere, which models indicated could cause enhanced equatorial Pacific SST gradients during the Plio-Pleistocene (Lee & Poulsen, 2006).…”

Section: Equatorial Mean State and The Late Miocene Global Coolingmentioning

confidence: 65%

“…The asymmetric mean state (6.5 to ~5.7 Ma) may indicate further ITF restriction, coincident with increased benthic δ 18 O and Antarctic cryosphere expansion (Drury et al, , ; Nathan & Leckie, ; Ohneiser et al, ). The asymmetric mean state could also reflect shoaling of the CAS, which models have shown could result in a shallower eastern equatorial Pacific thermocline (Zhang et al, ).…”

Section: Discussionmentioning

confidence: 99%

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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: Equatorial Mean State and The Late Miocene Global Coolingmentioning

confidence: 65%

Section: Discussionmentioning

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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“…This timing is remarkably similar to the timing of the Messinian Salinity Crisis (MSC), in which the Mediterranean Sea shrank and ultimately dried up from 5.96 to 5.33 Ma (16). The cause of the MSC has also been the subject of much debate (17,18), but recent work argues it was triggered by glacio-eustatic sea-level fall in response to expansion of Antarctic ice sheets at ∼6 Ma (19) and that the period of maximum aridity (the "Messinian gap") corresponds to one or two glacial periods near 5.53 ± 0.06 Ma (16,20). These glacial periods are part of a long-recognized, but somewhat enigmatic, sequence of latest Miocene glacials between ∼6.2 and 5.5 Ma, which included up to 18 glacial-interglacial cycles on a Significance This paper identifies two periods of enhanced aridity that are synchronous with faunal turnovers in southern South America.…”

mentioning

confidence: 66%

Mio-Pliocene aridity in the south-central Andes associated with Southern Hemisphere cold periods

Amidon

Fisher

Burbank

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Although Earth’s climate history is best known through marine records, the corresponding continental climatic conditions drive the evolution of terrestrial life. Continental conditions during the latest Miocene are of particular interest because global faunal turnover is roughly synchronous with a period of global glaciation from ∼6.2–5.5 Ma and with the Messinian Salinity Crisis from ∼6.0–5.3 Ma. Despite the climatic and ecological significance of this period, the continental climatic conditions associated with it remain unclear. We address this question using erosion rates of ancient watersheds to constrain Mio-Pliocene climatic conditions in the south-central Andes near 30° S. Our results show two slowdowns in erosion rate, one from ∼6.1–5.2 Ma and another from 3.6 to 3.3 Ma, which we attribute to periods of continental aridity. This view is supported by synchrony with other regional proxies for aridity and with the timing of glacial ‟cold” periods as recorded by marine proxies, such as the M2 isotope excursion. We thus conclude that aridity in the south-central Andes is associated with cold periods at high southern latitudes, perhaps due to a northward migration of the Southern Hemisphere westerlies, which disrupted the South American Low Level Jet that delivers moisture to southeastern South America. Colder glacial periods, and possibly associated reductions in atmospheric CO2, thus seem to be an important driver of Mio-Pliocene ecological transitions in the central Andes. Finally, this study demonstrates that paleo-erosion rates can be a powerful proxy for ancient continental climates that lie beyond the reach of most lacustrine and glacial archives.

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“…Although ice expansion has traditionally been inferred in East Antarctica, Ross Sea seismic evidence also suggests West Antarctic Ice Sheet (WAIS) expansion during the MMCT (Bart, 2003). However, the timing of the Ross Sea event, WAIS development, and forcings and feedbacks involved in the MMCT remain enigmatic, as does the subsequent climate and ice sheet history of the relatively late Miocene (e.g., Kennett, 1977;De Santis et al, 1995;Zachos et al, 2001;Ohneiser et al, 2015;Herbert et al, 2016). During the mid-Pliocene, global sea levels are estimated to have been ~20 ± 10 m above present-day levels, indicating a reduction/collapse of both the Greenland Ice Sheet and the WAIS (Miller et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Ross Sea West Antarctic Ice Sheet History

McKay¹,

Santis²,

Kulhanek³

et al. 2019

Proceedings of the International Ocean Discovery Program

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The marine-based West Antarctic Ice Sheet (WAIS) is currently locally retreating because of shifting wind-driven oceanic currents that transport warm waters toward the ice margin, resulting in ice shelf thinning and accelerated mass loss. Previous results from geologic drilling on Antarctica's continental margins show significant variability in ice sheet extent during the late Neogene and Quaternary. Climate and ice sheet models indicate a fundamental role for oceanic heat in controlling ice sheet variability over at least the past 20 My. Although evidence for past ice sheet variability is available from ice-proximal marine settings, sedimentary sequences from the continental shelf and rise are required to evaluate the extent of past ice sheet variability and the associated forcings and feedbacks. International Ocean Discovery Program Expedition 374 drilled a latitudinal and depth transect of five sites from the outer continental shelf to rise in the central Ross Sea to resolve Neogene and Quaternary relationships between climatic and oceanic change and WAIS evolution. The Ross Sea was targeted because numerical ice sheet models indicate that this sector of Antarctica responds sensitively to changes in ocean heat flux. Expedition 374 was designed for optimal data-model integration to enable an improved understanding of Antarctic Ice Sheet (AIS) mass balance during warmer-than-present climates (e.g., the Pleistocene "super interglacials," the mid-Pliocene, and the Miocene Climatic Optimum). The principal goals of Expedition 374 were to • Evaluate the contribution of West Antarctica to far-field ice volume and sea level estimates;• Reconstruct ice-proximal oceanic and atmospheric temperatures to quantify past polar amplification; • Assess the role of oceanic forcing (e.g., temperature and sea level) on AIS variability; • Identify the sensitivity of the AIS to Earth's orbital configuration under a variety of climate boundary conditions; and • Reconstruct Ross Sea paleobathymetry to examine relationships between seafloor geometry, ice sheet variability, and global climate.To achieve these objectives, postcruise studies will• Use data and models to reconcile intervals of maximum Neogene and Quaternary ice advance and retreat with far-field records of eustatic sea level; • Reconstruct past changes in oceanic and atmospheric temperatures using a multiproxy approach; • Reconstruct Neogene and Quaternary sea ice margin fluctuations and correlate these records to existing inner continental shelf records; • Examine relationships among WAIS variability, Earth's orbital configuration, oceanic temperature and circulation, and atmospheric pCO 2 ; and • Constrain the timing of Ross Sea continental shelf overdeepening and assess its impact on Neogene and Quaternary ice dynamics.Expedition 374 departed from Lyttelton, New Zealand, in January 2018 and returned in March 2018. We recovered 1292.70 m of R.M. McKay et al. Expedition 374 summary IODP Proceedings 2 V o l u m e 3 7 4

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Antarctic glacio-eustatic contributions to late Miocene Mediterranean desiccation and reflooding

Cited by 60 publications

References 69 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

Mio-Pliocene aridity in the south-central Andes associated with Southern Hemisphere cold periods

Ross Sea West Antarctic Ice Sheet History

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