Project Details
Projekt
Antarctic ice-sheet dynamics during the Mid-Oligocene Glacial Interval (MOGI)
Applicant
Professor Dr. Oliver Friedrich
Subject Area
Geology
Term
since 2024
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 546930216
The Oligocene represents the transition from a world lacking large-scale continental ice sheets to one dominated by these factors and is therefore marked as “early coolhouse world” that exhibits an unipolar glaciated climate. While the long-term evolution of the Oligocene cryosphere is well known, the short-term dynamics of the Antarctic ice sheets are still enigmatic due to the lack of high-quality, high-resolution ice-volume reconstructions. Therefore, the principal objectives of the proposed project are to critically test the available early Oligocene ice-volume reconstructions and to provide high-quality quantitative estimates of Antarctic ice-sheet fluctuations for the initiation and ‘deglaciation’ phase of the so-called Mid-Oligocene Glacial Interval (MOGI) for the time interval 28.2–27.3 Ma. This will include a critical testing if the MOGI was indeed a time of increasing ice volume or if bottom-water cooling played a significant role, and to obtain a mechanistic understanding of the processes that led to the ice-sheet dynamics observed for the early Oligocene. Altogether, it will be tested how dynamic the AIS was under the unipolar, relatively cold climate conditions of the early Oligocene and how this dynamic compared to the warmer late Oligocene. These objectives will be reached through the generation of high-resolution (i.e., suborbital) paleoclimate proxy records for the initiation and ‘deglaciation’ phase of the early Oligocene MOGI interval. Proxy records to be generated are based on benthic foraminiferal geochemistry (Mg/Ca and stable isotopes) to reconstruct changes in seawater δ18O (δ18Osw) – a proxy for continental ice-volume. The proposed suborbital-resolution records (~1.5 kyr) will be generated from Expedition 378 Site U1553 (southern Campbell Plateau, southern Pacific Ocean). In short, the proposed project will address three major research questions which are (1) What was the rate of early Oligocene ice-volume variability during the MOGI?, (2) To what extent are early Oligocene glacials of the MOGI comparable to those from the late Oligocene warm interval and the Plio-/Pleistocene?, and (3) Does the evolving topography of the Antarctic continent led to a less dynamic Antarctic ice sheet during the early Oligocene?. IODP Site U1553, the site focused upon in the here proposed project, provides the opportunity to work at high temporal resolution using exquisitely preserved benthic foraminifera to answer these questions.
DFG Programme
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