Paleoenvironmental reconstructions and
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Ar/
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Ar geochronology of seven eroded monogenetic volcanoes
near the Hobbs Coast, Marie Byrd Land, West Antarctica provide proxy records of WAIS paleo-ice-levels in Miocene-Pliocene times. Interpretations, based on lithofacies analysis, indicate whether the volcanoes erupted below, near, or
above the level of the ice sheet. Our interpretations differ significantly from previous interpretations as they highlight
the abundant evidence for ice-volcano interactions at emergent paleoenvironments but limited evidence of higher-than-present syn-eruptive ice-levels. Evidence for subglacial volcanic paleoenvironments is limited to Kennel Peak, a ~8 Ma
volcano where a pillow lava sequence extending 25 m above current ice level overlies an inferred glacial till and
unconformity. A major complication in the Hobbs Coast region is that the volcanism occurred on interfluves between
regions of fast-flowing ice. Such a setting precludes establishing precise regional paleo-ice-levels although the presence
or absence of ice at times of eruptions can be inferred.