Featured Research

from universities, journals, and other organizations

Jade Sheds Light On Guatemala's Geologic History

Date:
August 19, 2009
Source:
American Museum of Natural History
Summary:
The shifting of tectonic plates in Central America has been poorly understood -- until now. New research on jade found along fault lines in Guatemala is helping geologists piece the puzzle of the past 130 million years.

A new analysis of jade found along the Motagua fault that bisects Guatemala is underscoring the fact that this region has a more complex geologic history than previously thought. Because jade and other associated metamorphic rocks are found on both sides of the fault, and because the jade to the north is younger by about 60 million years, a team of geologists posits in a new research paper that the North American and Caribbean plates have done more than simply slide past each other: they have collided. Twice.

Related Articles


"Now we understand what has happened in Guatemala, geologically," says one of the authors, Hannes Brueckner, Professor of Geology at Queens College, City University of New York. "Our new research is filling in information about plate tectonics for an area of the world that needed sorting."

Jade is a cultural term for two rare metamorphic rocks known as jadeitite (as discussed in the current research) and nephrite that are both extremely tough and have been used as tools and talismans throughout the world. The jadeitite (or jadeite jade) is a sort of scar tissue from some collisions between Earth's plates. As ocean crust is pushed under another block, or subducted, pressure increases with only modest rise in temperature, squeezing and drying the rocks without melting them. Jade precipitates from fluids flowing up the subduction channel and into the chilled, overlying mantle that becomes serpentinite. The serpentinite assemblage, which includes jade and has a relatively low density, can be uplifted during subsequent continental collisions and extruded along the band of the collision boundary, such as those found in the Alps, California, Iran, Russia, and other parts of the world.

The Motagua fault is one of three subparallel left-lateral strike-slip faults (with horizontal motion) in Guatemala and forms the boundary between the North American and Caribbean tectonic plates. In an earlier paper, the team of authors found evidence of two different collisions by dating mica found in collisional rocks (including jade) from the North American side of the fault to about 70 million years ago and from the southern side (or the Caribbean plate) to between 120 and 130 million years ago. But mica dates can be "reset" by subsequent heating. Now, the authors have turned to eclogite, a metamorphic rock that forms from ocean floor basalt in the subduction channel. Eclogite dates are rarely reset, and the authors found that eclogite from both sides of the Motagua dates to roughly 130 million years old.

The disparate dating of rocks along the Motagua can be explained by the following scenario: a collision 130 million years ago created a serpentinite belt that was subsequently sliced into segments. Then, after plate movement changed direction about 100 million years ago, a second collision between one of these slices and the North American plate reset the mica clocks in jadeitite found on the northern side of the fault to 70 million years. Finally, plate motion in the last 70 million years juxtaposed the southern serpentinites with the northern serpentinites, which explains why there are collisional remnants on both sides of the Motagua.

"All serpentinites along the fault line formed at the same time, but the northern assemblage was re-metamorphosed at about 70 million year ago. There are two collision events recorded in the rocks observed today, one event on the southern side and two on the northern," explains author George Harlow, Curator in the Division of Earth and Planetary Sciences at the American Museum of Natural History. "Motion between plates is usually not a single motion—it is a series of motions.

This research was published in Earth and Planetary Science Letters. In addition to Brueckner and Harlow, authors on this research paper include Hans Lallemant of Rice University in Houston, Texas; Virginia Sisson of the University of Houston in Texas; Sidney Hemming of Columbia University's Lamont-Doherty Earth Observatory, New York; Uwe Martens of Stanford University, California; Tatsuki Tsujimori of Okayama University in Japan, and Sorena Sorenson of the National Museum of Natural History in Washington, D.C. The National Science Foundation funded the research.


Story Source:

The above story is based on materials provided by American Museum of Natural History. Note: Materials may be edited for content and length.


Cite This Page:

American Museum of Natural History. "Jade Sheds Light On Guatemala's Geologic History." ScienceDaily. ScienceDaily, 19 August 2009. <www.sciencedaily.com/releases/2009/07/090727191921.htm>.
American Museum of Natural History. (2009, August 19). Jade Sheds Light On Guatemala's Geologic History. ScienceDaily. Retrieved April 17, 2015 from www.sciencedaily.com/releases/2009/07/090727191921.htm
American Museum of Natural History. "Jade Sheds Light On Guatemala's Geologic History." ScienceDaily. www.sciencedaily.com/releases/2009/07/090727191921.htm (accessed April 17, 2015).

Share This


More From ScienceDaily



More Earth & Climate News

Friday, April 17, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Planet Defence Conference Tackles Asteroid Threat

Planet Defence Conference Tackles Asteroid Threat

AFP (Apr. 17, 2015) Scientists gathered at a European Space Agency (ESA) facility outside Rome this week for the Planetary Defence Conference 2015 to discuss how to tackle the potential threat from asteroids hitting Earth. Duration: 00:54 Video provided by AFP
Powered by NewsLook.com
Gulf Scarred, Resilient 5 Years After BP Spill

Gulf Scarred, Resilient 5 Years After BP Spill

AP (Apr. 17, 2015) Five years after the Deepwater Horizon spill in the Gulf of Mexico, splotches of oil still dot the seafloor and wads of tarry petroleum-smelling material hide in pockets in the marshes of Barataria Bay. (April 17) Video provided by AP
Powered by NewsLook.com
Boeing's Autonomous Underwater Vehicles (AUV) Echo Ranger

Boeing's Autonomous Underwater Vehicles (AUV) Echo Ranger

Scuba Diving (Apr. 16, 2015) Seventy years after its service in World War II, NOAA, working with private industry partners, has confirmed the location and condition of the USS Independence. Resting upright in 2,600 feet of water off California’s Farallon Islands, the aircraft carrier’s hull and flight deck are clearly visible in sonar images, with what appears to be a plane in the carrier’s hangar bay. Video provided by Scuba Diving
Powered by NewsLook.com
California Drought Renews Thirst for Desalination Plants

California Drought Renews Thirst for Desalination Plants

Reuters - US Online Video (Apr. 16, 2015) As California&apos;s water crisis deepens, a one billion dollar desalination plant is set to go on-line near San Diego. Nathan Frandino 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