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

The northeast Antarctic Peninsula (NEAP) region is currently showing signs of significant environmental
change, evidenced by acceleration of glacial retreat and collapse of both Larsen-A and -B ice shelves within
the past 15 years. However, data on the past extent of the eastern margin of the Antarctic Peninsula Ice
Sheet (APIS) and its Holocene retreat history are sparse, and hence we cannot yet put the recent changes
into a long-term context. In order to investigate the timing of deglaciation, we present 16 new cosmogenic
10Be surface exposure ages from sites on northern James Ross Island (Cape Lachman, Johnson Mesa and
Terrapin Hill) and Seymour Island. The majority of the ages cluster around 6e10 ka, with three significantly
older (25e31 ka). We combine these ages with existing terrestrial and marine radiocarbon deglaciation
ages, and a compilation of existing swath bathymetry data, to quantify the temporal and spatial character
of the regional glacial history. Ice had begun to retreat from the outer shelf by 18.3 ka, reaching Seymour
Island by w8 ka. Northern James Ross Island began to deglaciate around the time of the Early Holocene
Climatic Optimum (c. 11e9.5 ka). Deglaciation continued, and a transition from grounded to floating ice in
Prince Gustav Channel occurred around 8 ka, separating the James Ross Island ice cap from the APIS. This
occurred shortly before Prince Gustav Channel ice shelf began to disintegrate at 6.2 ka. Our results suggest
there may be a bathymetric control on the spatial pattern of deglaciation in the NEAP.