@ARTICLE{Pańczyk_Magdalena_Isotope_2009, author={Pańczyk, Magdalena and Nawrocki, Jerzy and Williams, Ian S.}, volume={vol. 30}, number={No 4}, journal={Polish Polar Research}, pages={379-391}, howpublished={online}, year={2009}, publisher={Polish Academy of Sciences}, publisher={Committee on Polar Research}, abstract={The Blue Dyke and Jardine Peak are subvertical hypabyssal intrusions cutting a stratiform volcanic sequence in the Admiralty Bay area on King George Island (South Shetlands, Antarctica ). The rocks are porphyritic, crystal-rich basaltic andesites. Tiny zircon crystals were used for single grain SHRIMP U-Pb dating. The mean ages calculated for the zircon populations from both intrusions indicates Late Oligocene (Chattian) formations. Zircon grains from the Blue Dyke gave the mean age of 27.9±0.3 Ma, whereas those from the Jardine Peak are slightly younger displaying the mean age of 25.4 ± 0.4 Ma: a Late Oligocene (Chattian) crystallization age the inferred of both these intrusions. These are much younger than previous Eocene K-Ar and Ar-Ar ages for such rocks and suggest that formation of the King George Island intrusions can be related to tectonic processes that accompanied the opening of the Drake Passage.}, type={Article}, title={Isotope age constraint for the Blue Dyke and Jardine Peak subvertical intrusions of King George Island , West Antarctica}, URL={http://www.czasopisma.pan.pl/Content/110559/PDF/PPR30-379.pdf}, keywords={Antarctica, King George Island, Late Oligocene, U-Pb SHRIMP dating}, }