DOI: 10.5285/b73794b8-5874-4c51-a2f2-fa895553dfcb
title: Chronostratigraphic data constraining Holocene glacial readvance from the Fildes Peninsula, South Shetland Islands, northern Antarctic Peninsula.

description: The dataset comprises of chronostratigraphic data from the Fildes Peninsula, King George Island, South Shetland Islands. The data consists of Radiocarbon (C-14) ages, which were obtained by Accelerator Mass Spectrometry (AMS) dating of marine mollusc shells, terrestrial mosses and seaweed layers embedded in sediments, and Cosmogenic Helium-3 (He-3) nuclide surface exposure dating (CSED). The data have been used to constrain deglaciation and climate-glacier dynamics on the Fildes Peninsula. Data collected in this study were funded by: Centro de Investigaciones en Ciencias de la Tierra (CICTERRA), the Direccion Nacional del Antartico/Instituto Antartico Argentino (DNA/IAA) in the framework of the Project PICTA, 2011 - 0102, IAA 'Geomorfologia y Geologia Glaciar del Archipielago James Ross e Islas Shetland del Sur, Sector Norte de la Peninsula Antartica'; the Alfred Wegener Institute (AWI) research program Polar regions and Coasts in a changing Earth System (PACES II); IMCONet (FP7 IRSES, action no. 318718); the Natural Environment Research Council (NERC/BAS-CGS Grant no.81); the NERC/BAS science programmes CACHE-PEP: Natural climate variability - extending the Americas palaeoclimate transect through the Antarctic Peninsula to the pole and GRADES-QWAD: Quaternary West Antarctic Deglaciations. We thank the crews of the Argentine research station 'Carlini' and the adjoined German Dallmann-Labor (AWI) Laboratory, the Uruguayan research station 'Artigas', the Russian Bellingshausen Station, the Chinese Great Wall Station, Base Presidente Eduardo Frei Montalva, the Brazilian Navy Almirante Maximiano, the UK Navy HMS Endurance and NERC/BAS James Clark Ross for logistical support during the 2006, 2011, 2014 and 2015 field seasons.
description: Chronostratigraphic data Radiocarbon (C-14) dating: Moraines adjacent to the BIC were mapped and interpreted from field observations and satellite images (DigitalGlobe, Catalogue ID: 1030010020C0C900; Google Earth, 2006 and 2011). Contour lines are derived from the Antarctic Digital Database with elevation data (+/-5 m) obtained from the Instituto Antartico Uruguayo (1997). Radiocarbon ages from moraines and stratigraphic sections were obtained by Accelerator Mass Spectrometry (AMS) dating of marine mollusc shells, terrestrial mosses and seaweed layers embedded in sediments and represent maximum ages for BIC glacier readvance Calibration of marine sample radiocarbon ages (marine shells) was undertaken in Oxcal v. 4.4 using the Marine20 calibration curve (Bronk Ramsey, 2009; Heaton et al., 2020), and a newly recalculated local marine reservoir age offset (deltaR) of 666+/-76 C-14 years, which represents the weighted mean delta R of four radiocarbon-dated marine samples collected prior to 1950 CE from the northern Antarctic Peninsula and Signy Island in the online Marine20 database (see references). Terrestrial and aquatic moss samples were calibrated using the Southern Hemisphere SHCal20 calibration curve in Oxcal v. 4.4 (Hogg et al., 2020). Post-bomb (&gt;1950 CE) ages were corrected according to 13C/12C isotopic ratios from measured pMC with the 'present day' pMC value defined as 107.5% (2010 CE) and calibrated using the SHCal13 SH Zone 1-2 Bomb curve in CALIBomb (Reimer and Reimer, 2004; Hua et al., 2013). Cosmogenic Helium-3 (He-3) nuclide surface exposure dating (CSED): Large boulders more than 50 cm in diameter on the NW Bellingshausen Ice Cap (BIC) glacial foreland were surveyed and classified. Three samples were collected for He-3 CSED using a hammer and chisel to remove the upper few centimetres of exposed surfaces. Surface shielding due to snow cover was minimised by sampling from wind-exposed localities (cf. Johnson et al., 2012, 2017, 2020; Glasser et al., 2014; Lindow et al., 2014). Laboratory analysis for 10Be cosmogenic nuclide surface exposure dating followed the procedures of Kohl and Nishiizumi, (1992) and Binnie et al., (2015) Code, data, all packages used, and package references, can be found via the github repository in the references.
description: Cosmogenic data: Quartz purity was determined prior to dissolution by ICP-OES Radiocarbon data: Samples were prepared at the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research and British Antarctic Survey. AMS measurements were undertaken at ETH Zurich and Beta Analytical, Miami, and 13C/12C isotope ratios were used to calculate Conventional Radiocarbon Ages.
description: Cosmogenic data: Differential GPS (dGPS; WGS84 ellipsoid) data for erratic boulders were obtained using a GPS Trimble Pathfinder ProXH. As geodetic reference, we used the landmark DALL 66019M002 (-62.237870; -58.664545;, ellipsoidal height 39.376 m) at the Argentine Carlini base, c. 17 km from the sampled erratics. Post-processed uncertainties for the samples were less than 0.1 m in altitude and in the horizontal. Sample concentrations are relatively low but the maximum blank subtraction was less than 6%. Analytical uncertainties for the 10Be concentrations were derived by summing in quadrature the uncertainty in the mass of Be added during sample processing (estimated to be 1% at 1 sigma) and the AMS measurement uncertainties of both the samples and blank. Radiocarbon data: Pre-bomb calibrated ages have been rounded to the nearest 10 years, and to the nearest hundred years in the manuscript text to reflect realistic total (internal and external) uncertainties. Post-bomb ages have been rounded to the nearest year.