From pluton intrusion to its exhumation: a case study from Barnard Point Batholith, Livingston Island, South Shetland Archipelago, Antarctica

Abstract

Three samples from the main phase of the Barnard Point Batholith of granodiorite from the sea level up to 463 m of Mac Kay Peak – are analyzed. The U-Pb zircon geochronology reveals magmatic crystallization at 43.89±032 Ma. The Ca-amphibole thermobarometry shows a shallow crustal level emplacement (5–3.5 km and temperatures of 810–750 °C). Two main episodes that correspond to the uplift of the Tangra Mountain and exhumation of the batholith are distinguished using apatite fission-track analysis. The models reveal initial very rapid cooling to ~ 80–90 °C between 40 and 33 Ma and a second episode of uplift and moderate cooling to surface temperatures between 22 and 15 Ma. The obtained positive age-altitude correlation suggests moderate exhumation rate of 340 m/Ma. The thermal modelling of the hypsometrically lowest sample reveals a later moderate cooling event to surface temperatures from 8 Ma to recent times, which corresponds to the Bransfield Rift initiation.