Holocene deglacial history of the northeast Antarctic Peninsula – A review and new chronological constraints

first_imgThe northeast Antarctic Peninsula (NEAP) region is currently showing signs of significant environmentalchange, evidenced by acceleration of glacial retreat and collapse of both Larsen-A and -B ice shelves withinthe past 15 years. However, data on the past extent of the eastern margin of the Antarctic Peninsula IceSheet (APIS) and its Holocene retreat history are sparse, and hence we cannot yet put the recent changesinto a long-term context. In order to investigate the timing of deglaciation, we present 16 new cosmogenic10Be surface exposure ages from sites on northern James Ross Island (Cape Lachman, Johnson Mesa andTerrapin Hill) and Seymour Island. The majority of the ages cluster around 6e10 ka, with three significantlyolder (25e31 ka). We combine these ages with existing terrestrial and marine radiocarbon deglaciationages, and a compilation of existing swath bathymetry data, to quantify the temporal and spatial characterof the regional glacial history. Ice had begun to retreat from the outer shelf by 18.3 ka, reaching SeymourIsland by w8 ka. Northern James Ross Island began to deglaciate around the time of the Early HoloceneClimatic Optimum (c. 11e9.5 ka). Deglaciation continued, and a transition from grounded to floating ice inPrince Gustav Channel occurred around 8 ka, separating the James Ross Island ice cap from the APIS. Thisoccurred shortly before Prince Gustav Channel ice shelf began to disintegrate at 6.2 ka. Our results suggestthere may be a bathymetric control on the spatial pattern of deglaciation in the NEAP.last_img read more