Featured Research

from universities, journals, and other organizations

The 'Fixed' Hotspot That Created Hawaii Was Not Stationary After All, Study Finds

Date:
August 6, 2003
Source:
Stanford University
Summary:
Geologists have long assumed that the Hawaiian Islands owe their existence to a "hotspot" -- stationary plumes of magma that rise from the Earth's mantle to form Mauna Loa, Kilauea and Hawaii's other massive volcanoes. But a new study posted on the online version of the journal Science disputes that long-standing paradigm by concluding that the fixed hotspot in the Pacific was not stationary after all.

Geologists have long assumed that the Hawaiian Islands owe their existence to a "hotspot" -- stationary plumes of magma that rise from the Earth's mantle to form Mauna Loa, Kilauea and Hawaii's other massive volcanoes. But a new study posted on the online version of the journal Science disputes that long-standing paradigm by concluding that the fixed hotspot in the Pacific was not stationary after all.

"Our research suggests that the Hawaiian hotspot actually drifted southward between 47 and 81 million years ago during the Late Cretaceous to Early Tertiary," said David Scholl, consulting professor of geophysics at Stanford University and senior research scientist emeritus with the U.S. Geological Survey in Menlo Park, Calif. "This finding will break across a very cherished idea about how things work in the innards of the Earth."

Scholl is one of 11 co-authors of the study that appears in the July 24 edition of Science Express online (www.sciencexpress.org). The lead author is geophysicist John A. Tarduno of the University of Rochester, who earned a doctoral degree at Stanford in 1987. His principal collaborator is second author Robert A. Duncan of Oregon State University.

Seamounts

Until now, the prevailing theory among geophysicists has been that, for millions of years, the massive Pacific Plate has been slowly drifting over a fixed hotspot deep in the mantle, creating a trail of volcanoes whose peaks emerge from the ocean as Maui, Oahu and the other islands that make up the 49th state. The Hawaiian Islands are part of a long chain of volcanoes collectively known as the Hawaiian-Emperor Seamounts that stretch some 3,600 miles along the floor of the Pacific -- from the Big Island of Hawaii to Alaska's Aleutian Trench.

The segment known as the Hawaiian Ridge, which includes the Hawaiian and Midway Islands, forms a neat line of volcanoes that extends some 1,800 miles northwest across the Pacific. At that point, the Hawaiian Ridge meets the Emperor Seamounts -- an older volcanic chain that abruptly changes course, stretching more than 1,000 miles almost due north to the Aleutian Trench. According to most researchers, this sharp northward bend records a change in the direction of the Pacific Plate as it passed over the fixed hotspot about 47 million years ago.

To test this hypothesis and determine the true origin of the Emperor Seamounts, Tarduno, Scholl and other scientists embarked on a two-month excursion aboard the research vessel JOIDES Resolution to collect samples of solidified lava flows from four submerged volcanoes that form part of the Seamounts chain. The expedition was conducted under the auspices of the Ocean Drilling Program, an international research effort to study the world's seafloors.

Argon and magnetite

When the voyage ended, the researchers conducted geochemical analyses of the lava samples to determine where and when they formed. Age was determined by the radiometric dating of two chemical elements -- potassium and argon.

When a rock forms, atoms of potassium start decaying into argon at a constant rate, regardless of changes in the rock's temperature, chemistry or pressure. By measuring the number of potassium-derived argon atoms in the samples, researchers were able to estimate that the submerged volcanoes formed some 45 million to 81 million years ago.

Tarduno and his team were able to determine where the volcanoes formed by analyzing a mineral called magnetite in the rock samples. As hot magma from an erupting volcano cools, magnetite residues align with the Earth's magnetic pole and become locked in place.

"The magnetite behaves like miniature compass needles: The closer they are to the Earth's magnetic pole, the steeper their position," Scholl explained. Researchers were able to verify the latitudes at which the Seamounts formed by determining the angles at which the magnetite had frozen.

Using these data, the research team concluded that the "fixed" Hawaiian hotspot probably crept southward between 81 million and 47 million years ago at a rate of about 44 millimeters a year, "changing our understanding of terrestrial dynamics," they wrote.

"Given the central role the Hawaiian-Emperor bend has played as an example of [tectonic] plate motion change, these observations now question whether major plates can undergo large changes in direction rapidly, and whether plate boundary forces alone can play a dominant role in controlling plate motions," they noted. "These data sets indicate a much more active role of mantle convection in controlling the distribution of volcanic islands."

Fundamental questions

"This study raises fundamental questions about how the mantle works and how plates work," Scholl added. "What's really going on here? Why do these hotspots drift, and why do they suddenly stop? We know that the mantle moves, now we have to find out how deep the motion goes."

Future drilling experiments in other ocean basins could provide answers, he noted.

Other co-authors of the study are Rory D. Cottrell of the University of Rochester; Bernhard Steinberger of the Japan Marine Science and Technology Center; Thorvaldur Thordarson of the University of Hawaii; geophysics graduate student Bryan C. Kerr of Stanford; Clive R. Neal of the University of Notre Dame; Fred A. Frey of the Massachusetts Institute of Technology; Masayuki Torii of the Okayama University of Science; and Claire Carvallo of the University of Toronto. Funding was provided by the National Science Foundation.


Story Source:

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


Cite This Page:

Stanford University. "The 'Fixed' Hotspot That Created Hawaii Was Not Stationary After All, Study Finds." ScienceDaily. ScienceDaily, 6 August 2003. <www.sciencedaily.com/releases/2003/07/030725080732.htm>.
Stanford University. (2003, August 6). The 'Fixed' Hotspot That Created Hawaii Was Not Stationary After All, Study Finds. ScienceDaily. Retrieved April 21, 2014 from www.sciencedaily.com/releases/2003/07/030725080732.htm
Stanford University. "The 'Fixed' Hotspot That Created Hawaii Was Not Stationary After All, Study Finds." ScienceDaily. www.sciencedaily.com/releases/2003/07/030725080732.htm (accessed April 21, 2014).

Share This



More Earth & Climate News

Monday, April 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Ocean Drones Making Waves in Research World

Ocean Drones Making Waves in Research World

AP (Apr. 21, 2014) Two California companies are developing unmanned watercraft to study the ocean. The ocean drones can stay at sea for months to gather scientific data, patrol borders and protect endangered reefs. (April 21) Video provided by AP
Powered by NewsLook.com
Drought Concerns May Hurt Lake Tourism

Drought Concerns May Hurt Lake Tourism

AP (Apr. 18, 2014) Operators of recreational businesses on western reservoirs worry that ongoing drought concerns will keep boaters and other visitors from flocking to the popular summer attractions. (April 18) Video provided by AP
Powered by NewsLook.com
Man Claims He Found Loch Ness Monster With... Apple Maps?

Man Claims He Found Loch Ness Monster With... Apple Maps?

Newsy (Apr. 18, 2014) Andy Dixon showed the Daily Mail a screenshot of what he believes to be the mythical beast swimming just below the lake's surface. Video provided by Newsy
Powered by NewsLook.com
First Ever 'Female Penis' Discovered In Animal Kingdom

First Ever 'Female Penis' Discovered In Animal Kingdom

Newsy (Apr. 18, 2014) Not only are these newly discovered bugs' sex organs reversed, but they also mate for up to 70 hours. 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:
from the past week

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