April 26, 2010

New Research Rocks the World of Plate Tectonics

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Recent natural disasters, like the earthquake in the Qinghai province of China as well as the volcanic eruption in Iceland, spans the question, what causes these catastrophic events? And how do they occur? Researchers, Rice University’s Prof. Cin-Ty Lee, earth sciences, Rice University, look deep into the earth for answers.

At his Apr. 21 lecture, “Making and Destroying Continental Crust,” Lee shared his findings on the origins of continental crust (or lithosphere), the global water cycle, mantle geochemistry and continental weathering.

Reporting on his ongoing research with Emily Chin grad, Lee explained that the “tectonic and the petrologic origin is still an important, by not fully resolved, question.” Theory suggests that the melting of the mantle created the earth’s crust and the continents, but Lee argued that this theory is incorrect.

According to Lee, continents are “felsic,” or light colored rocks containing an abundance of feldspars, feldspathoids or silica.

However, due to heat from the Earth’s core, the heating of the mantle prevents felsic melts.

Lee aimed to understanding the felsic composition of the continents.  He studied batholiths in the Sierra Nevada and the Peninsular Ranges of California.

“Batholiths” include intrusive, igneous rocks that form from cooled magma deep in the earth’s crust.  They commonly include felsic or intermediate rock-types.

Lee and Chin investigated how mantle-derived magma separates into felsic and mafic counterparts to better understand the formation of the continents. This research provides a new image of the formation of the planet surface.

Lee also currently researches the global water cycle by studying the serpentinization of the upper part of the lithospheric mantle beneath oceans. “Serpentinization” is a geological, low-temperature, metamorphic process of heat and water that converts low-silica mafic and ultramafic rocks into serpentinite.

Because this process requires water, Lee thinks that “understanding how much of the oceanic lithospheric mantle is serpentinized is key to understanding how much water is recycled into the Earth’s interior by subduction, one leg of the global water cycle.”

Original Author: Maria Minsker