DOI: 10.5285/63bbaf4f-fe53-45a8-b2b5-d41adcf3d35f
title: 10Be surface exposure age data from Mt Murphy, Marie Byrd Land, Antarctica

description: This dataset comprises 52 cosmogenic 10Be surface exposure ages and associated analytical data from quartz-bearing rocks from Mount Murphy and surrounding nunataks in Marie Byrd Land, Antarctica. The samples - glacial erratics and bedrock - were collected between 2006 and 2016 by Joanne Johnson, Stephen Roberts and James Smith (British Antarctic Survey), in order to determine timing and duration of ice sheet thinning in the Amundsen Sea sector of the West Antarctic Ice Sheet, specifically thinning of Pope Glacier. The data are published and interpreted in the following paper: Johnson, J.S., Roberts, S.J., Rood, D.H., Pollard, D., Schaefer, J.M., Whitehouse, P.L., Ireland, L.C., Lamp, J.L., in review. Deglaciation of Pope Glacier implies widespread early Holocene ice sheet thinning in the Amundsen Sea sector of Antarctica. Earth & Planetary Science Letters. doi: xxxxx This data forms part of the ANiSEED project ('Amundsen Sea Embayment Exposure Dating'), funded by the Natural Environment Research Council (grants NE/K012088/1 and NE/K011278/1).
description: The dataset comprises 52 exposure ages from 3 sets of samples. 3 samples were collected in 2006 by Joanne Johnson (using helicopter support from RV Polarstern cruise ANT-XXXIII-4), and are published in Johnson et al., 2008. They have been recalculated here for consistency. The remaining 49 exposure ages are from samples collected in 2010 (by James Smith using helicopter support from RV Polarstern cruise ANT-XXVII-3) and in 2015-16 by Joanne Johnson and Stephen Roberts (supported by NERC grants NE/K012088/1 and NE/K011278/1). Samples from the surfaces of glacial erratics and bedrock were collected in the field using hand-held rock saw and chisel. These were then prepared at Lamont-Doherty Earth Observatory cosmogenic nuclide laboratory (USA) using procedures developed for high-sensitivity 10Be exposure dating. Analysis of 10Be/9Be ratios in each sample was undertaken by: PRIME lab, Purdue University, USA; the Center for Accelerator Mass Spectrometry (CAMS), Lawrence Livermore National Laboratory, USA; and Scottish Universities Environmental Research Centre (SUERC) AMS Laboratory. 10Be backgrounds were corrected with procedural blanks (a 9Be carrier-only sample that is processed alongside and identically to the samples), that ranged from &lt; 1,000 to ~150,000 total 10Be atoms. Corrections were between &lt;1 % to ~2.5 %. The 10Be exposure ages were then calculated using Version 3 of the online cosmogenic nuclide exposure age calculator hosted at https://hess.ess.washington.edu/. Topographic shielding was determined using the associated online geometric shielding calculator, v. 1.1. Zero erosion and a quartz density of 2.7 g cm-3 were assumed for all age calculations. The 10Be exposure ages in this dataset are reported using the LSDn scaling scheme of Lifton et al., 2014 (doi: 10.1016/j.epsl.2013.10.052), alongside the global 10Be production rate (PGLOBAL). More details on sample processing and exposure age calculations are provided in the referenced publications.
description: Software: Version 3 of the online cosmogenic nuclide exposure age calculator hosted at https://hess.ess.washington.edu/. Version 1.1. of the online geometric shielding calculator hosted at https://hess.ess.washington.edu/.