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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. [ABSTRACT FROM AUTHOR]

The Southeastern area of Livingston Island is built up by igneous rocks of the Eocene Barnard Point Pluton and related or younger dykes. Our new field and petrographic studies in the area show that the pluton consists of several main rock varieties namely gabbro, gabbrodiorite, granodiorite and granites, whose relationships evidences magma mixing processes. The internal parts of the former chamber contain levels enriched in mafic microgranular enclaves forming pronounced magmatic foliation, which towards western contact of the pluton transits to a subvertical N-S trending solid-state foliation and both parallelize the main foliation of the metamorphic host rocks. The latter evidences for a room creation and magma emplacement in tectonically active setting. [ABSTRACT FROM AUTHOR]