Overlapping volcanoes: The origin of Hilo Ridge, Hawaii
- 1School of Oceanography, University of Washington, Seattle, Washington 98195-7940, USA
- 2Department of Geological Sciences, University of Washington, Seattle, Washington 98195-1310, USA
Abstract
The submarine Hilo Ridge has been interpreted as a part of Mauna Kea volcano, but is crossed at ∼1100 m depth by a submerged shoreline terrace composed of basalts that are isotopically distinct from those of Mauna Kea and similar to those of Kohala volcano. This terrace evidently is a product of Kohala instead of Mauna Kea. Almost all of Hilo Ridge below the terrace therefore must predate the principal growth of Mauna Kea, which has superficially isolated the ridge from its Kohala source by overlapping its proximal segment. The Mauna Kea section penetrated by the Hawaii Scientific Drilling Project is predicted to be thinner than expected previously, owing to the overlap. Similar overlaps are suspected among other volcanoes and may cause significant changes in the understanding of Hawaiian volcanism.
Footnotes
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↵*Present address: Department of Geology, Washington State University, Pullman, Washington 99164-2812, USA
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- Accepted March 28, 2000.
- Received October 20, 1999.
- Revision received March 13, 2000.
- Geological Society of America
