Holocene sea-level history and tectonic implications derived from luminescence dating of raised beaches in Terra Nova Bay, Antarctica

초록

Raised beaches are amongst the most important and direct indicators of relative sea-level change and timing of degladation in Antarctica. Infrared stimulated luminescence dating of cobble surfaces on two sets of raised beaches in Terra Nova Bay in Victoria Land of Antarctica records relative sea-level change since the Mid-Holocene. This study includes dating on five raised beaches on Inexpressible Island (II-1 to II-5) and five raised beaches at Jang Bogo Station (JS-1 to JS-5). The raised beaches at Jang Bogo Station began to form before 6.0 +/- 0.8 ka, emerging at an average rate of 0.9 m/ka. The rate of emergence on Inexpressible Island was 1.6(+0.2)/(-0.1)m/ka from 4.8 +/- 0.5 to 1.1 +/- 0.1 ka, since when the rate has been 14.9(+1.8)/(-1.0)m/ka. The proximity of the two study sites suggests that glacier melting, and associated glacio-isostatic rebound alone cannot explain the difference between the rates of emergence at the two sets of raised beaches. This spatio-temporal difference in the emergence rates is likely the result of both local tectonics and glacio-isostatic rebound. This view is consistent with recent GPS geodetic analyses, albeit the geologic and geodetic data are on different temporal scales. Moreover, the rapid uplift since 1.1 ka on Inexpressible Island is likely due to vertical movement associated with active faulting.

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