ABSTRACT: The Oligocene-Miocene Transition (OMT) is an important interval in Earthâ€™s history, with substantial changes in Antarctic ice volume and mean temperature. The OMTis complicated in paleoclimatology, chronostratigraphy, and terminology, and there is a need for additional sites outside of the tropic/subtropics or Atlantic Basin to better understand the cause(s) and consequences of the OMT. Ocean Drilling Program Hole 744A sits on the southern edge of the Kerguelen Plateau, and is thus a sensitive recorder of changes on Antarctica and in the Indian Ocean sector of the Southern Ocean. Previous stratigraphic studies have concluded that the Oligocene/Miocene boundary is contained within a short coring gap (1 m) between Cores 744A-11 and 12. A new benthic foraminiferal stable isotope curve is at odds with the existing age model for the upper ~0.5mof Core 12. A number of different explanations for age models are discussed, and we find there is only one plausible explanation for the chronostratigraphy through Core 12. We suggest therewas a short (~150-200 kyr) hiatus, encompassing the peak Mi-1 excursion, based on interpreted magnetostratigraphy. This hiatus has no obvious lithologic expression.
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