Sedimentology of core PS1423-2

Investigations of the stratigraphy and facies within a 2.69m long gravity core (PS1423-2) from the southwestern Weddell Sea, Antarctica, indicate a significant change in the character of glaciomarine sedimentation since grounded ice withdrew from the continental shelf. Based On visual description, X-radiography, clast shape, particle-size analysis, physical properties and geochemical data, the core used in this analysis comprises five distinct units, from top to bottom: (i) massive diamicton, (ii) weakly to well-stratified diamicton, (iii) millimetre-scale laminated muds, with little or no coarse-clastic input, (iv) well- to weakly stratified diamicton, (V) massive diamicton. This succession is attributed to the variation in sedimentation associated with the recession of the grounding line of a previously advanced glacier. Grounded ice decoupled from the continental shelf to form an ice shelf, probably initiated by a rise in sea level in response to global climatic changes. Following disintegration of the ice shelf, sedimentation was influenced by marked variations in iceberg production. AMS derived 14C ages from the upper 46 cm of the core indicate that the succession has been deposited since the end of the most recent glacial maximum (late Plektocene), a conclusion supported by published data.