subvertical intrusions of King George Island

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 zir− con crystals were used for single...

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Bibliographic Details
Main Authors: Jardine Peak, Magdalena Pańczyk, Jerzy Nawrocki, Ian S. Williams
Other Authors: The Pennsylvania State University CiteSeerX Archives
Format: Text
Language:English
Subjects:
Key words
Antarctica
King George Island
Late Oligocene
U−Pb SHRIMP dating
Admiralty Bay
Blue Dyke
Drake Passage
Jardine Peak
Antarc*
Online Access:http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.625.7611
http://www.polar.pan.pl/ppr30/PPR30-379.pdf
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Summary: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 zir− con 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 ac− companied the opening of the Drake Passage.

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