DOI: 10.5285/8f275626-5f22-48df-95e5-cdc8f204a897
title: Beryllium-10 exposure ages for Pope Glacier from a scoria cone 1.5 km west of Mount Murphy in the Amundsen Sea Embayment

description: The dataset contains 12 new Be-10 cosmogenic nuclide surface exposure ages. The samples were collected from a scoria cone 1.5 km west of Mt. Murphy an exposed volcanic edifice adjacent to Pope Glacier in the Amundsen Sea Embayment, Antarctica. Samples of erratic cobbles which showed evidence of transport by ice were collected over the 2015-2016 AmuNdsen Sea Embayment Exposure Dating (ANISEED) Field Season, prepared at the CosmIC laboratory, Imperial College London and measured for Be-10 at the Australian Nuclear Science and Technology Organisation. Beryllium-10 concentrations were measured by Accelerated Mass Spectrometry (AMS). Samples were measured to determine timing of deglaciation of two rock outcrops to better constrain the ice sheet lowering history of Pope Glacier during the Holocene. Study forms part of the wider International Thwaites Glacier Collaboration Project (ITGC). Samples were collected by Dr. Joanne Johnson and Dr. Stephen Roberts (British Antarctic Survey), supported by field assistants Alistair Docherty and Iain Rudkin. Sample preparation for 10Be measurement was carried out by Jonathan Adams - PhD candidate affiliated with British Antarctic Survey/ Imperial College London under the supervision of Dr. Dylan Rood - Imperial College London. AMS measurements of Beryllium-10 concentrations were performed by Dr. Klaus Wilcken - Australia's Nuclear Science and Technology Organisation (ANSTO). National Science Foundation (NSF: Grant OPP-1738989) and Natural Environment Research Council (NERC: Grants NE/S006710/1, NE/S006753/1 and NE/K012088/1 and studentship to JRA). ITGC Contribution No. ITGC.
description: Quartz bearing erratic cobbles which showed evidence of transport by ice were collected at an exposed nunatak adjacent to Pope Glacier in the Amundsen Sea Embayment. Quartz mineral separation and Be-10 isotope dilution chemistry are largely based upon standard procedures (Kohl and Nishiizumi, 1992; Corbett, Bierman and Rood, 2016). The additional froth flotation step, used to separate feldspars from quartz was omitted as a precautionary measure (Nichols and Goehring, 2019). Once extracted from purified quartz, Be-10 AMS measurements were performed at the Australian Nuclear Science and Technology Organisation (ANSTO). Measurements were then normalized to the KN-5-3 standard with an assumed ratio of 6.320 x 10-12 (t1/2 = 1.36 Ma; Nishiizumi et al., 2007). Exposure ages were calculated via inputting Be-10 nuclide concentrations returned from AMS measurement using version 3 of the online calculators at hess.ess.washington.edu (Balco et al., 2008). The online calculators use the production rate scaling method for neutrons, protons and muons following Lifton et al., 2014 and summarised in Balco, 2017. Apparent exposure ages were reported assuming no erosion or snow cover and a material density of 2.7g cm-3
description: Sirius 6MV tandem accelerator (accelerated mass spectrometer) Version 3 of online calculator at hess.ess.washington.edu (formerly known as CRONUS Online calculator).
description: Be-10/Be-9 measurements are normalized to the KN-5-3 standard with an assumed ratio of 6.320 x 10^-12 (t1/2=1.36 Ma, Nishiizumi et al., 2007) Scoria cone (CIN) Be samples and process blanks BLK140920A/B were prepared for analysis at the CosmIC labs, Imperial College London. AMS analysis was performed at ANSTO, Australia