Antarctic ice-sheet dynamics of the early Miocene

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The principal objectives of the proposed project are to critically test available early Miocene sea-level/ice-volume reconstructions, to provide high-quality quantitative estimates of Antarctic ice-sheet fluctuations, and to obtain a mechanistic understanding of the processes that led to the ice-sheet dynamics observed for the early Miocene. Furthermore, it will be tested if the evolving Antarctic topography decreased the ability of the Antarctic continent to support a larger-than-today AIS in the early Miocene; leading to an even more dynamic AIS than compared to the late Oligocene. These objectives will be reached through the generation of paleoclimate proxy records for a specific time interval of the early Miocene (19.722-17.533 Ma). Proxy records to be generated are based on benthic foraminiferal geochemistry (Mg/Ca and stable isotopes) to reconstruct changes in seawater delta18O (delta18Osw) - a proxy for continental ice-volume. The proposed suborbital-resolution records will be generated from Expedition 342 Site U1406 (off Newfoundland, North Atlantic) and aim to document and understand the dynamics and evolution of obliquity-modulated Antarctic ice sheets. Providing this information will allow detailed insight into the evolution of the cryosphere for a critical interval of Cenozoic climate evolution (i.e., the dynamic climate of the early Miocene). Moreover, the data will allow a sophisticated comparison of the driving mechanisms behind glacial/interglacial cycles during two fundamentally different intervals of Earth’s history with respect to their climatic processes: the unipolar-glaciated early Miocene and the bipolar-glaciated Late Pleistocene. In short, the proposed project will address the following major research questions: (1) what was the rate of early Miocene ice-volume/sea-level variability? (2) does the evolving topography of the Antarctic continent lead to a more dynamic AIS? (3) is the amplitude of glacial/interglacial delta18Osw changes comparable between a unipolar vs. bipolar glaciated climate system? and (4) to what extent are early Miocene glacials comparable to those from the Pleistocene?