Neogene Record of Antarctic Peninsula Glaciation in Continental Rise Sediments: ODP Leg 178, Site 1095

Abstract

Site 1095 is the most distal of three continental rise sites drilled during Ocean Drilling Program Leg 178. A long (600 m), near-continuous section extends from the Holocene down to nearly 10-Ma sediments, comprising fine-grained turbidites, hemipelagites, and muddy contourites. Meter-scale lithologic cyclicity is seen in sediment facies, physical properties, composition, and grain size in the upper 300 m of the section, representing 0–7 Ma. The diatom content of the sediments suggests sea ice was a significant limitation on productivity only during the Pleistocene. Fine grain size implies that bottom currents were never significantly stronger that at present during the last 7 m.y. The presence of ice-rafted debris implies the Antarctic Peninsula was not deglaciated for any significant period during the “warm Pliocene” (3.2–4.5 Ma). Intermittent supply of fine terrigenous sediment to the rise is consistent with published depositional models showing the ice sheet grounded to the shelf edge during glacial periods. At some times, particularly during the late Miocene, processes related to submarine channel switching and lobe progradation may have masked climatic control on deposition at this site.