Featured Research

from universities, journals, and other organizations

On the shoulder of a giant: Precursor volcano to the island of O'ahu discovered

Date:
May 16, 2014
Source:
University of Hawaii ‑ SOEST
Summary:
Researchers recently discovered that O'ahu, Hawai'i actually consists of three major Hawaiian shield volcanoes, not two, as previously thought. Extending almost 100 km WNW from the western tip of the island of O'ahu is the submarine Ka'ena Ridge, a region that has now been recognized to represent a precursor volcano to the island of O'ahu, and on whose flanks the Wai'anae and Ko'olau Volcanoes later formed.

Map showing schematically the distribution of the three volcanoes now thought to have made up the region of O'ahu, Hawai'i. From oldest to youngest these are the Ka'ena, Wai'anae, and Ko'olau Volcanoes. Upper panel: bold dashed lines delineate possible rift zones of the three volcanoes; also shown are the major landslide deposits around O'ahu. The lower panel shows how the three volcanic edifices overlap.
Credit: J. Sinton, et al., UH SOEST

Researchers from the University of Hawai'i -- Mānoa (UHM), Laboratoire des Sciences du Climat et de L'Environment (France), and Monterey Bay Aquarium Research Institute recently discovered that O'ahu actually consists of three major Hawaiian shield volcanoes, not two, as previously thought. The island of O'ahu, as we know it today, is the remnants of two volcanoes, Wai'anae and Ko'olau. But extending almost 100 km WNW from Ka'ena Point, the western tip of the island of O'ahu, is a large region of shallow bathymetry, called the submarine Ka'ena Ridge. It is that region that has now been recognized to represent a precursor volcano to the island of O'ahu, and on whose flanks the Wai'anae and Ko'olau Volcanoes later formed.

Prior to the recognition of Ka'ena Volcano, Wai'anae Volcano was assumed to have been exceptionally large and to have formed an unusually large distance from its next oldest neighbor -- Kaua'i. "Both of these assumptions can now be revised: Wai'anae is not as large as previously thought and Ka'ena Volcano formed in the region between Kauai and Wai'anae," noted John Sinton, lead author of the study and Emeritus Professor of Geology and Geophysics at the UHM School of Ocean and Earth Science and Technology (SOEST).

In 2010 scientists documented enigmatic chemistry of some unusual lavas of Wai'anae. "We previously knew that they formed by partial melting of the crust beneath Wai'anae, but we didn't understand why they have the isotopic composition that they do," said Sinton" Now, we realize that the deep crust that melted under Waianae is actually part of the earlier Ka'ena Volcano."

This new understanding has been a long time in the making. Among the most important developments was the acquisition of high-quality bathymetric data of the seafloor in the region. This mapping was greatly accelerated after UH acquired the Research Vessel Kilo Moana, equipped with a high-resolution mapping system. The new data showed that Ka'ena Ridge had an unusual morphology, unlike that of submarine rift zone extensions of on-land volcanoes. Researchers then began collecting samples from Ka'ena and Wai'alu submarine Ridges. The geochemical and age data, along with geological observations and geophysical data confirmed that Ka'ena was not part of Waianae, but rather was an earlier volcanic edifice; Wai'anae must have been built on the flanks of Ka'ena.

"What is particularly interesting is that Ka'ena appears to have had an unusually prolonged history as a submarine volcano, only breaching the ocean surface very late in its history," said Sinton. Much of our knowledge of Hawaiian volcanoes is based on those that rise high above sea level, and almost all of those formed on the flanks of earlier ones. Ka'ena represents a chance to study a Hawaiian volcano that formed in isolation on the deep ocean floor.

Despite four different cruises and nearly 100 rock samples from Ka'ena, researchers say they have only begun to observe and sample this massive volcanic edifice. While this article was in press, SOEST scientists visited Ka'ena Ridge again -- this time with the UH's newest remotely operated vehicle, ROV Lu'ukai -- and collected new rock samples from some of its shallowest peaks. With these new samples Sinton and colleagues hope to constrain the timing of the most recent volcanism on Ka'ena.


Story Source:

The above story is based on materials provided by University of Hawaii ‑ SOEST. Note: Materials may be edited for content and length.


Journal Reference:

  1. J. M. Sinton, D. E. Eason, M. Tardona, D. Pyle, I. van der Zander, H. Guillou, D. A. Clague, J. J. Mahoney. Ka'ena Volcano--A precursor volcano of the island of O'ahu, Hawai'i. Geological Society of America Bulletin, 2014; DOI: 10.1130/B30936.1

Cite This Page:

University of Hawaii ‑ SOEST. "On the shoulder of a giant: Precursor volcano to the island of O'ahu discovered." ScienceDaily. ScienceDaily, 16 May 2014. <www.sciencedaily.com/releases/2014/05/140516101951.htm>.
University of Hawaii ‑ SOEST. (2014, May 16). On the shoulder of a giant: Precursor volcano to the island of O'ahu discovered. ScienceDaily. Retrieved October 22, 2014 from www.sciencedaily.com/releases/2014/05/140516101951.htm
University of Hawaii ‑ SOEST. "On the shoulder of a giant: Precursor volcano to the island of O'ahu discovered." ScienceDaily. www.sciencedaily.com/releases/2014/05/140516101951.htm (accessed October 22, 2014).

Share This



More Earth & Climate News

Wednesday, October 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

San Diego Zoo's White Rhinos Provide Hope for the Critically Endangered Species

San Diego Zoo's White Rhinos Provide Hope for the Critically Endangered Species

Reuters - Light News Video Online (Oct. 22, 2014) — The pair of rare white northern rhinos bring hope for their species as only six remain in the world. Elly Park reports. Video provided by Reuters
Powered by NewsLook.com
Trick-or-Treating Banned Because of Polar Bears

Trick-or-Treating Banned Because of Polar Bears

Buzz60 (Oct. 21, 2014) — Mother Nature is pulling a trick on the kids of Arviat, Canada. As Mara Montalbano (@maramontalbano) tells us, the effects of global warming caused the town to ban trick-or-treating this Halloween. Video provided by Buzz60
Powered by NewsLook.com
Traditional Farming Methods Gaining Ground in Mali

Traditional Farming Methods Gaining Ground in Mali

AFP (Oct. 20, 2014) — He is leading a one man agricultural revolution in Mali - Oumar Diatabe uses traditional farming methods to get the most out of his land and is teaching others across the country how to do the same. Duration: 01:44 Video provided by AFP
Powered by NewsLook.com
How Detroit's Money Woes Led To U.N.-Condemned Water Cutoffs

How Detroit's Money Woes Led To U.N.-Condemned Water Cutoffs

Newsy (Oct. 20, 2014) — The United Nations says water is a human right, but should it be free? Detroit has cut off water to residents who can't pay, and the U.N. isn't happy. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins