facebook
twitter
rss
account
search
search
 

'Fossil' tectonic plate seen under Calif.

March 18, 2013 at 6:45 PM   |   Comments

PROVIDENCE, R.I., March 18 (UPI) -- A geologic anomaly 60 miles under central California is a remnant of an ancient oceanic plate pushed under North America 100 million years ago, scientists say.

Known as the Isabella anomaly, the large mass of cool, dehydrated material is a "fossil" slab of the Farallon oceanic plate, linked to known Farallon slabs at similar depths under Washington, Oregon and Baja California in Mexico, Brown University geophysicists reported Monday.

It is also due east of a known fragment still off the California coast, they said.

Most of the Farallon plate has been driven deep into the Earth's mantle since the Pacific and North American plates began converging about 100 million years ago, forming the San Andreas Fault at their boundary.

Off the west coast of North America, the Farallon plate fragmented, leaving a few small remnants at the surface that stopped subducting and became part of the Pacific plate, researchers said.

"Many had assumed that these pieces would have broken off quite close to the surface," Brown researcher Donald Forsyth said.

"We're suggesting that they actually broke off fairly deep, leaving these large slabs behind."

The findings could force scientists to re-examine the tectonic history of western North America, Forsyth said.

© 2013 United Press International, Inc. All Rights Reserved. Any reproduction, republication, redistribution and/or modification of any UPI content is expressly prohibited without UPI's prior written consent.
Most Popular
1
New dinosaur species with giant nose discovered in Utah New dinosaur species with giant nose discovered in Utah
2
Perth's first iPhone buyer immediately drops brand new phone on live TV Perth's first iPhone buyer immediately drops brand new phone on live TV
3
'Finding Nemo' has some basis in science... some 'Finding Nemo' has some basis in science... some
4
Report: Facebook Messenger app is loaded with spyware Report: Facebook Messenger app is loaded with spyware
5
Android phones to join iPhone in saying no to the police Android phones to join iPhone in saying no to the police
Trending News
Video
x
Feedback