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Geochronologia skał wulkanicznych centralnej i południowej części Wyspy Króla Jerzego (Szetlandy Południowe, Zachodnia Antarktyka)

Pańczyk M.

Przegląd Geologiczny

2013

Vol. 61, nr 2

117--119

New isotopic and paleomagnetic studies of volcanic rocks from the central and southern part of the King George Island and Penguin Island were carried out. The combination of three dating methods: single grain U-Pb dating of separated zircons, whole-rock 40Ar-39Ar dating and magnetostratigraphy allow distinguishing five magmatic activity phases: the oldest, late Cretaceous (Campanian), early to middle Eocene (about 53–43 Ma), late Eocene (about 37–35 Ma), late Oligocene (about 28–25 Ma) and, the youngest, late Pliocene to Holocene.

Isotopic ages of selected magmatic rocks from King George Island (West Antarctica ) controlled by magnetostratigraphy

Nawrocki J., Pańczyk M., Williams I.

Geological Quarterly

2011

Vol. 55, No. 4

301-322

Isotopic and palaeomagnetic studies were carried out in the central part of King George Island. Selected mafic to intermediate igneous rocks were sampled for this purpose. Single-grain U-Pb dating of zircons from basalts to dacites was controlled by a whole rock 40Ar-39Ar data and the magnetostratigraphy. Five magmatic activity phases were distinguished in the SE coast of King George Island. The oldest, late Cretaceous (Campanian) phase represented by basalts of the Uchatka Point Formation are followed by the early to middle Eocene (~53–43 Ma) phase documented by the lava flows whose ages decrease from SW to NE. Next younger magmatic activity phases were recorded by the lava flows or vertical intrusions emplaced in the late Eocene (~37–35 Ma), late Oligocene (~~28-25 Ma) and late Pliocene to Holocene. The early to middle Eocene magmatic activity phase was the most extensive, producing the largest volume of magma in the study area. The new age determinations allow a more precise and credible stratigraphic correlation of the interbeds of sedimentary rocks observed in some places within the magmatic succession. The glacial provenance of the Herv' Cove diamictite is not obvious. It might represent a mountain river environment. Intense volcanic activity could be additional factor modelling the climate conditions of Antarctica in Paleogene