New understanding of feldspar elasticity may explain seismic discontinuity
A Florida State University geology researcher is going deep below the Earth's surface to understand how some of the most abundant minerals that comprise the Earth's crust change under pressure.
In a paper published today in Scientific Reports, Assistant Professor of Geology Mainak Mookherjee explores how feldspar, one of the most important minerals in the Earth's crust, changes under pressure. Typically, materials become stiffer when pressure is applied, but Mookherjee found that these pale-colored crystals actually become softer under extreme pressures.
"I am interested in exploring these materials at extreme conditions," Mookherjee said. "Feldspar is very abundant in the earth's crust so we need to understand its elastic property."
Mookherjee's work shows that at a depth of about 30 kilometers from the Earth's surface, feldspar decomposes to denser mineral phases such as pyroxene and quartz. The densification of feldspar could partially explain a scientific observation called seismic discontinuity across the Earth's crust and mantle.
This seismic discontinuity, also called Mohorovicic discontinuity, is the boundary between the Earth's crust and mantle. It was first observed in 1909 by a Croatian scientist Andrija Mohorovicic who realized that seismograms from shallow-focus earthquakes had two sets of waves -- one that followed a direct path near the Earth's surface, i.e., crust, and the other arriving faster and probably refracted from the underlying higher-velocity medium mantle.
"This is the first study of the elastic properties of feldspar at high pressure," Mookherjee said. "And it provides very new insight and a novel way of accounting for the sharp Mohorovicic discontinuity."
Scientists have been working since the late 1950s to understand the Mohorovicic discontinuity that separates the Earth's outermost layer -- oceanic and continental crust -- with the underlying mantle. Last year, researchers from the drill ship JOIDES Resolution made attempts to drill a bore hole across the discontinuity, but fell short. Further drilling attempts are planned for future.
"We care about the mineral structures in the deep Earth and how they transform to denser crystal structures within the Earth," Mookherjee said. "Through a thorough understanding of the atomic scale structures at extreme conditions and how they influence the properties of the Earth materials, it is possible to gain valuable insight into deep Earth dynamics."
Mookherjee did his work through computer simulations at the FSU Research Computing Center and facilities at Argonne National Laboratory. The research was funded by the National Science Foundation.
Other researchers contributing to the article are Dhenu Patel, a Tallahassee high school student who interned in Mookherjee's lab last summer; Olle Heinonen from Argonne National Laboratory; Anant Hariharan from Cornell University; Ketan Maheshwari from University of Pittsburgh; and David Mainprice from Université de Montpellier.
Kathleen Haughney | EurekAlert!
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
19.07.2018 | Materials Sciences
19.07.2018 | Earth Sciences
19.07.2018 | Life Sciences