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Age and Evolution of the Volcanoes of Tutuila, American Samoa

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Title:Age and Evolution of the Volcanoes of Tutuila, American Samoa
Authors:McDougall, Ian
Date Issued:Oct 1985
Publisher:University of Hawai'i Press
Citation:McDougall I. 1985. Age and evolution of the volcanoes of Tutuila, American Samoa. Pac Sci 39(4): 311-320.
Abstract:Tutuila is a basaltic volcanic island within the east southeasterly
trending Samoa Island chain in the Pacific Ocean. Potassium-argon ages on 38
whole rock samples of lavas and intrusives demonstrate that the main period of
subaerial volcanism occurred over a relatively short interval of about 0.6 Ma in
the Early Pleistocene. The major shield volcano, Pago, was built between about
1.54 and 1.28 Ma ago; its large caldera formed approximately 1.27 ± 0.02 Ma
ago. Partial filling of the caldera by volcanics occurred from shortly after its
formation until about 1.14 Ma ago, and activity on Pago Volcano ended with
emplacement of trachyte bodies which have ages of 1.03 ± 0.01 Ma. Construction
of the smaller satellitic Olomoana and Taputapu volcanoes, on the eastern
and western extensions of the main rift zone through Pago Volcano, took place
over much the same time interval as the volcanism on Pago. The youthful basaltic
volcanism on the Manu'a Islands, east of Tutuila, allows a rate of migration of
the center of volcanism of about 10cmjyr to be estimated. These results are
broadly consistent with a hot spot origin for the volcanoes.
Appears in Collections: Pacific Science Volume 39, Number 4, 1985

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