Mid-late Pleistocene glacimarine sedimentary processes of high-latitude, deep-sea sediment drift (Antarctic Peninsula Pacific Margin)

The effects of glaciation on sediment drifts is recognised from marked sedimentary facies variation in deep seacores taken from the continental rise of the Antarctic Peninsula Pacific margin. Nineteen sediment cores were visuallydescribed, logged for magnetic susceptibility, and X-radiographed. About 1000 analyses were performed for grain size,clay minerals and biostratigraphy (foraminifera, nannofossils and diatoms). Four sediment types associated withdistinct sedimentary processes are recognised based on textural/compositional analysis. (1) Hemipelagic mud formsthe bulk of the interglacial sediment, and accumulated from the pelagic settling of bioclasts and ice-rafted/windtransporteddetritus. (2) Terrigenous mud forms the bulk of the glacial sediment, and accumulated from acombination of sedimentary processes including turbidity currents, turbid plumes, and bottom current reworking ofnepheloid layers. (3) Silty deposits occurring as laminated layers and lenses, represent the lateral spillout of lowdensityturbidity currents. (4) Lastly, glacial/interglacial gravelly mud layers derive from settling of ice-rafted detritus.Five depositional settings are interpreted within sediment Drift 7, each characterised by the dominance/interaction ofone or several depositional processes. The repetitive succession of typical sedimentary facies is inferred to reflect asequence of four climatic stages (glaciation, glacial, deglaciation, and interglacial), each one characterised by adistinctive clay mineral assemblage and bioclastic content. Variations in clay mineral assemblage within interglacialstage 5 (core SED-06) suggest minor colder climatic fluctuations, possibly correlatable with substages 5a to5e.