Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Taking the Pulse of Mountain Formation in the Andes

04.06.2014

Research Points to a Rapid Surface Uplift of Mountain Ranges

Scientists have long been trying to understand how the Andes and other broad, high-elevation mountain ranges were formed. New research by Carmala Garzione, a professor of earth and environmental sciences at the University of Rochester, and colleagues sheds light on the mystery.


Photo by Carmala Garzione/University of Rochester.

Sedimentary deposits near Cerdas in the Altiplano plateau of Bolivia. These rocks contain ancient soils used to decipher the surface temperature and surface uplift history of the southern Altiplano.

In a paper published in Earth and Planetary Science Letters, Garzione explains that the Altiplano plateau in the central Andes—and most likely the entire mountain range—was formed through a series of rapid growth spurts.

“This study provides increasing evidence that the plateau formed through periodic rapid pulses, not through a continuous, gradual uplift of the surface, as was traditionally thought,” said Garzione. “In geologic terms, rapid means rising one kilometer or more over several millions of years, which is very impressive.”

It’s been understood that the Andes mountain range has been growing as the Nazca oceanic plate slips underneath the South American continental plate, causing the Earth’s crust to shorten (by folding and faulting) and thicken. But that left two questions: How quickly have the Andes risen to their current height, and what was the actual process that enabled their rise?

Several years ago (2006-2008), Garzione and several colleagues provided the first estimates of the timing and rates of the surface uplift of the central Andes (“Mountain Ranges Rise Much More Rapidly than Geologists Expected”) by measuring the ancient surface temperatures and rainfall compositions preserved in the soils of the central Altiplano, a plateau in Bolivia and Peru that sits about 12,000 feet above sea level. Garzione concluded that portions of the dense lower crust and upper mantle that act like an anchor on the base of the crust are periodically detached and sink through the mantle as the thickened continental plate heats up. Detachment of this dense anchor allows the Earth’s low density upper crust to rebound and rise rapidly.

More recently, Garzione and Andrew Leier, an assistant professor of Earth and Ocean Sciences at the University of South Carolina, used a relatively new temperature-recording technique in two separate studies in different regions of the Andes to determine whether pulses of rapid surface uplift are the norm, or the exception, for the formation of mountain ranges like the Andes.

Garzione and Leier (“Stable isotope evidence for multiple pulses of rapid surface uplift in the Central Andes, Bolivia”) both focused on the bonding behavior of carbon and oxygen isotopes in the mineral calcite that precipitated from rainwater; their results were similar.

Garzione worked in the southern Altiplano, collecting climate records preserved in ancient soils at both low elevations (close to sea level), where temperatures remained warm over the history of the Andes, and at high elevations where temperatures should have cooled as the mountains rose. The calcite found in the soil contains both the lighter isotopes of carbon and oxygen—12C and 16O—as well as the rare heavier isotopes—13C and 18O. Paleo-temperature estimates from calcite rely on the fact that heavy isotopes form stronger bonds.

At lower temperatures, where atoms vibrate more slowly, the heavy isotope 13C-18O bonds would be more difficult to break, resulting in a higher concentration of 13C-18O bonds in calcite, compared to what is found at warmer temperatures. By measuring the abundance of heavy isotope bonds in both low elevation (warm) sites and high elevation (cooler) sites over time, Garzione used the temperature difference between the sites to estimate the elevation of various layers of ancient soils at specific points in time.

She found that the southern Altiplano region rose by about 2.5 kilometers between 16 million and 9 million years ago, which is considered a rapid rate in geologic terms. Garzione speculates that the pulsing action relates to a dense root that grows at the boundary of the lower crust and upper mantle. As the oceanic plate slips under the continental plate, the continental plate shortens and thickens, increasing the pressure on the lower crust. The basaltic composition of the lower crust converts to a very high-density rock called eclogite, which serves as an anchor to the low-density upper crust. As this root is forced deeper into the hotter part of the mantle, it heats to a temperature where it can be rapidly removed (over several million years), resulting in the rapid rise of the mountain range.

“What we are learning is that the Altiplano plateau formed by pulses of rapid surface uplift over several million years, separated by long periods (several tens of million years) of stable elevations,” said Garzione. “We suspect this process is typical of other high-elevation ranges, but more research is needed before we know for certain.”

Peter Iglinski
Senior Press Officer, Science & Public Media
peter.iglinski@rochester.edu
Phone: 585-273-4726
Mobile: 585-764-7002

Peter Iglinski | newswise
Further information:
http://www.rochester.edu

Further reports about: Andes Bolivia Earth calcite dense isotope isotopes mantle soils temperature temperatures

More articles from Earth Sciences:

nachricht Greenhouse gases' millennia-long ocean legacy
04.08.2015 | Carnegie Institution

nachricht NASA sees heavy rainfall in Super Typhoon Soudelor
04.08.2015 | NASA/Goddard Space Flight Center

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Greenhouse gases' millennia-long ocean legacy

Continuing current carbon dioxide (CO2) emission trends throughout this century and beyond would leave a legacy of heat and acidity in the deep ocean. These...

Im Focus: Glaciers melt faster than ever

Glacier decline in the first decade of the 21st century has reached a historical record, since the onset of direct observations. Glacier melt is a global phenomenon and will continue even without further climate change. This is shown in the latest study by the World Glacier Monitoring Service under the lead of the University of Zurich, Switzerland.

The World Glacier Monitoring Service, domiciled at the University of Zurich, has compiled worldwide data on glacier changes for more than 120 years. Together...

Im Focus: Quantum Matter Stuck in Unrest

Using ultracold atoms trapped in light crystals, scientists from the MPQ, LMU, and the Weizmann Institute observe a novel state of matter that never thermalizes.

What happens if one mixes cold and hot water? After some initial dynamics, one is left with lukewarm water—the system has thermalized to a new thermal...

Im Focus: On the crest of the wave: Electronics on a time scale shorter than a cycle of light

Physicists from Regensburg and Marburg, Germany have succeeded in taking a slow-motion movie of speeding electrons in a solid driven by a strong light wave. In the process, they have unraveled a novel quantum phenomenon, which will be reported in the forthcoming edition of Nature.

The advent of ever faster electronics featuring clock rates up to the multiple-gigahertz range has revolutionized our day-to-day life. Researchers and...

Im Focus: Superfast fluorescence sets new speed record

Plasmonic device has speed and efficiency to serve optical computers

Researchers have developed an ultrafast light-emitting device that can flip on and off 90 billion times a second and could form the basis of optical computing.

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Success 4.0 – Is Your Company Fit for the Future? New Series of Events for Executives

04.08.2015 | Event News

3rd Euro Bio-inspired - International Conference and Exhibition on Bio-inspired Materials

23.07.2015 | Event News

Clash of Realities – International Conference on the Art, Technology and Theory of Digital Games

10.07.2015 | Event News

 
Latest News

Small tilt in magnets makes them viable memory chips

04.08.2015 | Information Technology

New Design Brings World’s First Solar Battery to Performance Milestone

04.08.2015 | Power and Electrical Engineering

Magnetism at Nanoscale

04.08.2015 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>