Petrological and geochemical compositions of beach sands of the Barton and Weaver peninsulas of King George Island, West Antarctica: implications for provenance and depositional history

Abstract

The provenance of modern beach sands from the Barton and Weaver peninsulas of King George Island, South Shetland Islands, West Antarctica was investigated based on their modal composition and geochemical data. The source rocks and provenance tectonic setting are interpreted as volcanic and plutonic rocks formed in the magmatic arc setting. This interpretation is generally consistent with the currently distributed bedrocks in the ice-free areas and tectonic setting of King George Island. However, the composition of beach sands of the Barton and Weaver peninsulas is different from distribution of bedrocks exposed in the ice-free areas of both peninsulas. The present beach sands are interpreted as previous subaqueous moraines that were eroded and transported by advancing glaciers across the both peninsulas and deposited in front of the glacier grounding line. In other words, sand sediments in the beaches of the two peninsulas were not derived from bedrocks currently exposed in ice-free areas, but it is interpreted that they were subaqueous moraines before deglaciation and were mixed with sediment derived from wave erosion of bedrocks and sediments of the paleoshoreline during the isostatic uplift of King George Island. Finally, they were reworked under the current beach environments.