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The first low-temperature thermochronological data from Thurston Island, West Antarctica, provide insights into the poorly constrained thermotectonic evolution of the paleo-Pacific margin of Gondwana since the Late Paleozoic. Here we present the first apatite fission track and apatite (U-Th-Sm)/He data from Carboniferous to mid-Cretaceous (meta-) igneous rocks from the Thurston Island area. Thermal history modeling of apatite fission track dates of 145-92 Ma and apatite (U-Th-Sm)/He dates of 112-71 Ma, in combination with kinematic indicators, geological information, and thermobarometrical measurements, indicate a complex thermal history with at least six episodes of cooling and reheating. Thermal history models are interpreted to reflect Late Paleozoic to Early Mesozoic tectonic uplift of pre-Jurassic arc sequences, prior to the formation of an extensional Jurassic-Early Cretaceous back-arc basin up to 4.5 km deep, which was deepened during intrusion and rapid exhumation of rocks of the Late Jurassic granite suite. Overall Early to mid-Cretaceous exhumation and basin inversion coincided with an episode of intensive magmatism and crustal thickening and was followed by exhumation during formation of the Zealandia-West Antarctica rift and continental breakup. Final exhumation since the Oligocene was likely triggered by activity of the West Antarctic rift system and by glacial erosion.

New low-temperature thermochronological data from granitic basement of western Marie Byrd Land (MBL) provide insights into the still poorly constrained tectonic and topographic evolution of West Antarctica during and after continental breakup. Here, we present the first apatite (U-Th-Sm)/He data from the Devonian Ford Granodiorite and the mid-Cretaceous Byrd Coast Granite suites from the Ford Ranges and the Edward VII Peninsula. Thermal history modeling integrating apatite (U-Th-Sm)/He dates of 109-68 Ma with revised apatite fission track data in combination with geologic information indicates a thermal history with diachronous enhanced cooling at~100-60 Ma and subsequent slow cooling until the present day. Enhanced cooling at~100-70 Ma was related to activity of the West Antarctic rift system and to continental breakup, thereby exhuming most samples to shallow crustal levels. Localized cooling at~75-60 Ma is interpreted as resulting from faulting in the eastern Ross Sea region. Slow cooling after~70-60 Ma corresponds with formation of erosion surfaces in western MBL. Comparison of our results from western MBL with data from the literature indicates progressive formation of erosion surfaces from west to east along the MBL-Thurston Island crustal blocks. Late Cenozoic activity of the West Antarctic rift system and MBL dome uplift appear to have caused only minor exhumation of <1.5 km in western MBL.

The stability of the West Antarctic Ice Sheet is threatened by the incursion of warm Circumpolar Deepwater which flows southwards via cross-shelf troughs towards the coast there melting ice shelves. However, the onset of this oceanic forcing on the development and evolution of the West Antarctic Ice Sheet remains poorly understood. Here, we use single- and multichannel seismic reflection profiles to investigate the architecture of a sediment body on the shelf of the Amundsen Sea Embayment. We estimate the formation age of this sediment body to be around the Eocene-Oligocene Transition and find that it possesses the geometry and depositional pattern of a plastered sediment drift. We suggest this indicates a southward inflow of deep water which probably supplied heat and, thus, prevented West Antarctic Ice Sheet advance beyond the coast at this time. We conclude that the West Antarctic Ice Sheet has likely experienced a strong oceanic influence on its dynamics since its initial formation.

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