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Late Cretaceous-Neogene trends in deep ocean temperature and continental ice volume: Reconciling records of benthic foraminiferal geochemistry (δ18O and Mg/Ca) with sea level history

Cramer, B. S. ; Miller, K. G. ; Barrett, P. J. ; Wright, J. D.

Journal of Geophysical Research, 2011-12, Vol.116 (C12), p.n/a, Article C12023 [Periódico revisado por pares]

Washington: Blackwell Publishing Ltd

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  • Título:
    Late Cretaceous-Neogene trends in deep ocean temperature and continental ice volume: Reconciling records of benthic foraminiferal geochemistry (δ18O and Mg/Ca) with sea level history
  • Autor: Cramer, B. S. ; Miller, K. G. ; Barrett, P. J. ; Wright, J. D.
  • Assuntos: benthic foraminifera ; Chemical elements ; Climate change ; Earth ; Geobiology ; Geochemistry ; Geophysics ; ice volume ; Isotopes ; Mg/Ca ; Oceanography ; Oceans ; Paleoclimate science ; Paleontology ; sea level ; temperature ; Trace elements ; δ18O
  • É parte de: Journal of Geophysical Research, 2011-12, Vol.116 (C12), p.n/a, Article C12023
  • Notas: istex:6524F6E5605EF4A0CCA02151250FF2793748E1B3
    ark:/67375/WNG-W7NJQTFH-D
    National Science Foundation - No. OCE-0927663
    ArticleID:2011JC007255
  • Descrição: We reconstruct trends in ice volume and deep ocean temperature for the past 108 Myr, resolving variations on timescales of ∼2 Myr and longer. We use a sea level record as a proxy for ice volume, a benthic foraminiferal Mg/Cabf record as a proxy for temperature, and a benthic foraminiferal δ18Obf record as a proxy for both. This allows us to construct dual estimates of temperature and ice volume variations for the interval 10–60 Ma: extracting temperature from δ18Obf by using sea level as a proxy for ice volume to constrain the δ18Osw component, and extracting seawater δ18Osw (which reflects ice volume) from δ18Obf by using Mg/Cabf to constrain the temperature component. Each of these approaches requires numerous assumptions, but the range of plausible solutions are concordant on timescales >2 Myr and within an uncertainty of ±2°C temperature and ±0.4‰ δ18Osw. The agreement between the two approaches for the last 50 Myr provides empirical justification for the use of δ18Obf, Mg/Cabf, and sea level records as robust climate proxies. Our reconstructions indicate differences between deep ocean cooling and continental ice growth in the late Cenozoic: cooling occurred gradually in the middle–late Eocene and late Miocene–Pliocene while ice growth occurred rapidly in the earliest Oligocene, middle Miocene, and Plio‐Pleistocene. These differences are consistent with climate models that imply that temperatures, set by the long‐term CO2 equilibrium, should change only gradually on timescales >2 Myr, but growth of continental ice sheets may be rapid in response to climate thresholds due to feedbacks that are not yet fully understood. Key Points Records of d180, Mg/Ca, and sea level are reconcilable over the Cenozoic Mg/Ca_bf sensitivities to T and Mg/Ca_sw must either be both high or both low Ice volume and temperature variations are not tightly coupled in the Cenozoic
  • Editor: Washington: Blackwell Publishing Ltd
  • Idioma: Inglês
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