Contributions to the petrography and geochronology of volcanic rocks from the leeward Hawaiian Islands

GSA Bulletin
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Abstract

Petrographic and chemical analyses of basalt from Nihoa Island, Necker Island, French Frigate Shoals, and Midway Atoll, all in the leeward part of the Hawaiian chain, confirm that these islands are subaerial remnants of tholeiitic shield volcanoes similar to those that form the principal Hawaiian Islands. Chemistry suggests that Gardner Pinnacles may be part of the alkalic cap on a tholeiitic shield. Weighted mean potassium-argon ages of 7.0 ± 0.3 m.y. for Nihoa, 10.0 ± 0.4 m.y. for Necker, 11.7 ± 0.4 m.y. for French Frigate, and 17.9 ± 0.6 m.y. for Midway demonstrate that the ages of these volcanoes increase northwestward, continuing the trend of increasing age away from the active volcano of Kilauea shown by the main islands. The increase in age with distance along the chain, however, appears to be nonlinear. The results support the general hypothesis that the volcanoes of the Hawaiian chain have a common origin and were formed as the Pacific plate moved northwestward over a melting spot in the mantle.

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Publication type Article
Publication Subtype Journal Article
Title Contributions to the petrography and geochronology of volcanic rocks from the leeward Hawaiian Islands
Series title GSA Bulletin
DOI 10.1130/0016-7606(1974)85<727:CTTPAG>2.0.CO;2
Volume 85
Issue 5
Year Published 1974
Language English
Publisher Geological Society of America
Description 12 p.
First page 727
Last page 738
Country United States
State Hawaii
Other Geospatial French Frigate Shoals, Midway Atoll, Necker Island, Nihoa Island
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