The Oligocene–Miocene Boundary – Antarctic Climate Response to Orbital Forcing

Recent AU :2 high-resolution Oligocene–Miocene oxygen isotopic records revealed a relatively transient, ca. 2myr period, 1m amplitude cyclicity in isotopic values (Oi and Mi events, respectively). Intriguingly, it has been suggested that these isotopic excursions in oceanic dO were linked to ephemeral growth and decay in Antarctic ice sheets. A great deal of effort in the palaeoceanography community has been focused on developing techniques and gathering further records to determine if the Antarctic ice has behaved in such a transient manner in the past and indeed what factors might have led to the rapid growth and decay of ice sheets. Deciphering between temperature and ice-volume influences in the deep-sea isotopic record has proven somewhat difficult. Approaches have included the sampling of sediment from beneath different water masses, development of an independent palaeothermometer using magnesium/calcium ratios and improving the resolution and accuracy of coastal sea-level records. Despite these advances it 1 3 5