Geochronological data from the Hudson Mountains, Antarctica

Geological fieldwork was carried out in the Hudson Mountains during the 2005/6 and 2019/20 Antarctic summers to help understand the glacial history of the Pine Island Glacier region of West Antarctica. To accurately determine the crystallisation age of a suite of granitoid glacial erratics, we conducted a detailed analysis of zircon U-Pb geochronology. The dataset here provides U-Pb zircon geochronology data for 10 rock samples, collected from the Hudson Mountains. The data were collected in November 2024 at University College London. The analyses were conducted by Andrew Carter (University College London). This work was funded by NERC grant (NE/S006710/1) to Joanne Johnson.

Geological fieldwork was carried out in the Hudson Mountains during the 2005/6 and 2019/20 Antarctic summers. The crystallization age of 10 samples from these expeditions were analysed using zircon U-Pb geochronology. Zircon U-Pb geochronology used laser ablation inductively coupled mass spectrometry (LA-ICP-MS) facilities (Agilent 7700 coupled to a New Wave Research 193 nm excimer laser) at the London Geochronology Centre based in University College London. Heavy minerals were separated from bulk sediment samples using standard density liquid and magnetic separation procedures. Zircon-enriched extracts were mounted in hard epoxy resin on glass slides and polished for analysis.Typical laser spot sizes of 25 µm were used with a 7-10 Hz repetition rate and a fluence of 2.5 J/cm2. Background measurement before ablation lasted 15 seconds and laser ablation dwell time was 25 seconds. The external zircon standard was Plesovice, which has a TIMS reference age 337.13 ± 0.37 Ma (Sléma et al., 2008). Standard errors on isotope ratios and ages include the standard deviation of 206Pb/238U ages of the Plesovice standard zircon.Time-resolved signals that record isotopic ratios with depth in each crystal were processed using GLITTER 4.5, data reduction software, developed by the ARC National Key Centre for Geochemical Evolution and Metallogeny of Continents (GEMOC) at Macquarie University and CSIRO Exploration and Mining. Processing enabled filtering to remove spurious signals owing to overgrowth boundaries, weathering, inclusions, or fractures.

U-Pb ages were calculated using the 206Pb/238U ratios for samples dated as <1.1 Ga, and the 207Pb/206Pb ratios was used for older grains. Discordance was determined using (207Pb/235U - 206Pb/238U) / 206Pb/238U) and similar for 207Pb/206Pb ages.

Data was processed using software by Ludwig (2012) and Vermeesch (2018)