HISTORY OF THE LAST GLACIAL MAXIMUM AND SUBSEQUENT RECESSION ALONGSIDE HATHERTON GLACIER, ANTARCTICA

Well-constrained glacial geologic data from the maximum and termination of the last ice age afford key insights into the behavior of the Antarctic Ice Sheet (AIS) under a rapidly changing climate and offer benchmarks for model simulations. Here, we present new data on the timing and style of the local last glacial maximum and subsequent deglaciation of Hatherton Glacier, an outlet of the AIS in the Ross Sea sector.

The current paradigm is that during the last glacial maximum (LGM), the expanded AIS grounded across what today is the Ross Sea. This grounded Ross Sea Ice Sheet caused inflowing ice from outlet glaciers and ice streams entering the embayment from East and West Antarctica, respectively, to thicken. Widespread deposits in the adjacent and now ice-free valleys provide evidence of these outlet glaciers achieving and then abandoning their LGM positions. However, previous chronologic information from Hatherton Glacier affords conflicting stories of the ice sheet’s LGM history, with one interpretation casting doubt on whether the outlet glacier thickened at all during the maximum of the last glaciation. We re-evaluated the LGM history of Hatherton Glacier by carrying out our own systematic radiocarbon dating study using more than 150 dates of subfossil algae from glacial deposits and from former ice-dammed ponds associated with the ice-margin. Our work shows that the last high-stand of Hatherton Glacier occurred approximately 10 ka and subsequent ice recession was gradual throughout the Holocene. This new chronology, constructed from three sites along the glacier, is consistent with evidence elsewhere in the Transantarctic Mountains that suggests maximum ice levels during the last ice age were reached during the termination of the global ice age, possibly as a result of increased precipitation.