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.

Related Articles


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 November 26, 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 November 26, 2014).

Share This


More From ScienceDaily



More Earth & Climate News

Wednesday, November 26, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Antarctic Sea Ice Mystery Thickens... Literally

Antarctic Sea Ice Mystery Thickens... Literally

Newsy (Nov. 25, 2014) — Antarctic sea ice isn't only expanding, it's thicker than previously thought, and scientists aren't sure exactly why. Video provided by Newsy
Powered by NewsLook.com
3D Map of Antarctic Sea Ice to Shed Light on Climate Change

3D Map of Antarctic Sea Ice to Shed Light on Climate Change

Reuters - Innovations Video Online (Nov. 24, 2014) — A multinational group of scientists have released the first ever detailed, high-resolution 3-D maps of Antarctic sea ice. Using an underwater robot equipped with sonar, the researchers mapped the underside of a massive area of sea ice to gauge the impact of climate change. Ben Gruber reports. Video provided by Reuters
Powered by NewsLook.com
Car Park Solution for Flexible Green Energy

Car Park Solution for Flexible Green Energy

Reuters - Innovations Video Online (Nov. 24, 2014) — A British solar power start-up says that by covering millions of existing car park spaces around the UK with flexible solar panels, the country's power problems could be solved. Suzannah Butcher reports. Video provided by Reuters
Powered by NewsLook.com
Yellow-Spotted Turtles Rescued from Trafficking

Yellow-Spotted Turtles Rescued from Trafficking

Reuters - Light News Video Online (Nov. 24, 2014) — Hundreds of Amazon River turtles released into the wild in Peru. Sharon Reich reports. Video provided by Reuters
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