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Full-Text Articles in Life Sciences
Middle Miocene Ice Sheet Dynamics, Deep‐Sea Temperatures, And Carbon Cycling: A Southern Ocean Perspective, Amelia E. Shevenell, James P. Kennett, David W. Lea
Middle Miocene Ice Sheet Dynamics, Deep‐Sea Temperatures, And Carbon Cycling: A Southern Ocean Perspective, Amelia E. Shevenell, James P. Kennett, David W. Lea
Marine Science Faculty Publications
Relative contributions of ice volume and temperature change to the global ∼1‰ δ18O increase at ∼14 Ma are required for understanding feedbacks involved in this major Cenozoic climate transition. A 3‐ma benthic foraminifer Mg/Ca record of Southern Ocean temperatures across the middle Miocene climate transition reveals ∼2 ± 2°C cooling (14.2–13.8 Ma), indicating that ∼70% of the increase relates to ice growth. Seawater δ18O, calculated from Mg/Ca and δ18O, suggests that at ∼15 Ma Antarctica's cryosphere entered an interval of apparent eccentricity‐paced expansion. Glaciations increased in intensity, revealing a central role for internal climate …
Antarctic Sediment Chronology By Programmed-Temperature Pyrolysis: Methodology And Data Treatment, Brad E. Rosenheim, Mary Beth Day, Eugene Domack, Heather Schrum, Albert Benthien, John M. Hayes
Antarctic Sediment Chronology By Programmed-Temperature Pyrolysis: Methodology And Data Treatment, Brad E. Rosenheim, Mary Beth Day, Eugene Domack, Heather Schrum, Albert Benthien, John M. Hayes
Marine Science Faculty Publications
We report a detailed programmed-temperature pyrolysis/combustion methodology for radiocarbon (14C) dating of Antarctic sub-ice shelf sediments. The method targets the autochthonous organic component in sediments that contain a distribution of acid-insoluble organic components from several sources of different ages. The approach has improved sediment chronology in organic-rich sediments proximal to Antarctic ice shelves by yielding maximum age constraints significantly younger than bulk radiocarbon dates from the same sediment horizons. The method proves adequate in determining isotope ratios of the pre-aged carbon end-member; however, the isotopic compositions of the low-temperature measurements indicate that no samples completely avoided mixing with some proportion …