. 24/7 Space News .
TECTONICS
Geologists raise the speed limit for how fast continental crust can form
by Jennifer Chu for MIT News
Boston MA (SPX) Oct 07, 2020

stock image only

Although we can't see it in action, the Earth is constantly churning out new land. This takes place at subduction zones, where tectonic plates crush against each other and in the process plow up chains of volcanos that magma can rise through. Some of this magma does not spew out, but instead mixes and morphs just below the surface. It then crystallizes as new continental crust, in the form of a mountain range.

Scientists have thought that the Earth's mountain ranges are formed through this process over many millions of years. But MIT geologists have now found that the planet can generate new land far more quickly than previously thought.

In a paper published in the journal Geology, the team shows that parts of the Sierra Nevada mountain range in California rose up surprisingly fast, over a period of just 1.39 million years - more than twice as fast as expected for the region. The researchers attribute the rapid formation of land to a massive flare-up of magma.

"The really exciting thing about our findings is, with new high-precision geochronology, we were able to date how quickly that crust-building process happened, and we showed that this large volume of new crust was emplaced at an extremely rapid rate," says the study's lead author Benjamin Klein PhD '19, who carried out the research as a graduate student in MIT's Department of Earth, Atmospheric and Planetary Sciences (EAPS). "It was sort of an instant. It was a little over 1 million years, but in geologic times, it was super fast."

Klein's co-authors are Associate Professor Oliver Jagoutz and Research Scientist Jahandar Ramezani, both in EAPS.

A complete cross-section
The Sierra Nevada mountain range is a product of the collision of two tectonic plates: the westward-moving North American Plate and what at the time was the Farallon Plate, which ground slowly under the North American Plate, eventually sliding entirely into the Earth's mantle.

Around 100 million years ago, as both plates collided, they created first a chain of volcanos, then a towering mountain range that is today the Sierra Nevada.

"What is today the West Coast of the United States probably looked, back then, like the Andes today, with high elevations and a chain of large volcanos," Klein says.

For their study, the researchers concentrated on a geologic feature in the Sierra Nevada known as an intrusive suite - a large volume of rock that originally formed deep in the Earth's interior. Once crystallized, the rocks form a new, vertical column of continental crust.

They focused in particular on the Bear Valley Intrusive Suite, a unique formation in that it represents the vestiges of new continental crust that is today exposed on the surface, as a 40-mile stretch of granite. These rocks, which today lie horizontally along the mountain range, originally formed as a vertical column. Over time, this tower of new continental crust eroded, stretching and tilting into its current horizontal configuration.

"The Bear Valley Intrusive Suite gives us a complete cross-section of what these magma plumbing systems underlying large volcanos looked like, where normally we would have a limited snapshot," Klein says. "That allows us to think much more completely about how quickly new crust was being built."

A speed limit for new crust
The team collected rock samples across a region of the Sierra Nevada Batholith and brought them back to MIT to analyze their composition. They were able to determine the age of nine samples, using uranium-lead geochronology, a high-precision dating technique pioneered by the late MIT Professor Emeritus Sam Bowring. From each sample, the researchers isolated individual grains of zircon, a common mineral in rocks that contains uranium and some lead, the ratio of which scientists can measure to get an estimate of the rock's age.

From their analyses, Klein and his colleagues discovered that the age of all nine samples spanned a surprisingly short range, of just 1.39 million years. The team calculated an estimate for the amount of magma that must have crystallized to form the new crust that the samples represent. They found that about 250 cubic kilometers of magma likely rose up from Earth's interior and transformed into new crust - in just 1.39 million years.

"That's about two-and-a-half times faster than previous estimates for crust formation in the Sierras, which is a pretty big difference," Klein says. "It gives us a maximum speed limit for how quickly these things can actually happen."

Klein says that given the speed of this new crust formation, the likely cause was a magma flareup, or sudden burst of magmatic activity.

"The entire batholith was constructed in almost 200 million years, but we know over that period of time, there were periods when it was highly active and periods that were quieter, with less new material added," Klein says. "What we were able to show in this area was that, at least locally, the rate at which magma was brought in is much faster than the average rates that have been documented in the Sierras."

Geologists have thought that magma flare-ups occur as a result of unusual activity in the Earth, such as tectonic plates suddenly colliding at a faster rate. According to everything researchers have documented about the Bear Valley Intrusive Suite, however, no such activity transpired at the time the mountain range formed.

"There's no obvious trigger," Klein says. "The system is pretty much going along, and then we see this big burst of magma. So this challenges some basic notions in the field, and should inform how people think of how quickly these things could be happening today, in places like the Andes or the volcanos in Japan."

This research was supported, in part, by the National Science Foundation.

Research Report: "High-precision geochronology requires that ultrafast mantle-derived magmatic fluxes built the transcrustal Bear Valley Intrusive Suite, Sierra Nevada, California, USA"


Related Links
MIT News Office
Tectonic Science and News


Thanks for being there;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Monthly Supporter
$5+ Billed Monthly


paypal only
SpaceDaily Contributor
$5 Billed Once


credit card or paypal


TECTONICS
The age of the Earth's inner core revised
Austin TX (SPX) Aug 24, 2020
By creating conditions akin to the center of the Earth inside a laboratory chamber, researchers have improved the estimate of the age of our planet's solid inner core, putting it at 1 billion to 1.3 billion years old. The results place the core at the younger end of an age spectrum that usually runs from about 1.3 billion to 4.5 billion years, but they also make it a good bit older than a recent estimate of only 565 million years. What's more, the experiments and accompanying theories help p ... read more

Comment using your Disqus, Facebook, Google or Twitter login.



Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

TECTONICS
ISS Crew continues troubleshooting as tests isolate small leak

Russia reports 'non-standard' air leak on Space Station

Trump tech war with China changes the game for US business

ISS moves to avoid space debris

TECTONICS
SpaceX aborts Starlink satellite launch attempt

Gryphon Technologies wins $14M DARPA task order to support the DRACO program

NASA, SpaceX to launch first Commercial Crew rotation mission to International Space Station

United Launch Alliance scrubs spy satellite launch 2nd time this week

TECTONICS
NASA's New Mars Rover Is Ready for Space Lasers

ExoMars moves on

Study: Mars has four bodies of water underneath surface

Could life exist deep underground on Mars

TECTONICS
NASA chief warns Congress about Chinese space station

China's new carrier rocket available for public view

China sends nine satellites into orbit by sea launch

Chinese spacecraft launched mystery object into space before returning to Earth

TECTONICS
Swarm announces pricing for world's lowest-cost satellite communications network

NanoAvionics launches second satellite for Lacuna Space's growing IoT satellite constellation

Machine-learning nanosats to inform global trade

SpaceX postpones Starlink launch as thick clouds persist

TECTONICS
Secretive Big Data firm Palantir makes low-key stocks debut

NASA looks to advance 3D Printing construction systems for the Moon and Mars

EPC Space announces family of space level qualified power transistors

3D-printed, transparent fibers can sense breath, sounds, cell movements

TECTONICS
Search for New Worlds at Home with NASA's Planet Patrol Project

CHEOPS space telescope makes ultra-precise temperature and size measurements of an unusual giant planet

Let them eat rocks

Evolution of radio-resistance is more complicated than previously thought

TECTONICS
SwRI study describes discovery of close binary trans-Neptunian object

JPL meets unique challenge, delivers radar hardware for Jupiter Mission

Astronomers characterize Uranian moons using new imaging analysis

Jupiter's moons could be warming each other









The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us.