Ultramafic rocks make up about 1 percent of the Earth's surface and occur near regions undergoing rapid population and industrial growth, Maher said. More than 50 other deposits of exceptionally high-grade magnesite are distributed in the California Coast Ranges alone. Sequestering CO2 emissions at these sites could play a significant role in curbing global warming, she added.
"We've been looking at the geologic structure and veining at Red Mountain to try and understand how hard ultramafic rock could be transformed into magnesite," Maher said.
The Stanford team estimates that Red Mountain originally held nearly 1 million metric tons of magnesite, of which about 83 percent has been mined.
"One million metric tons of magnesite is the equivalent of sequestering 140,000 metric tons of carbon in mineral form," said graduate student Pablo Garcia del Real.
"Our goal is to use the vast reservoirs of magnesium stored in ultramafic rocks to chemically bind with CO2 and form magnesite. But as we discovered at Red Mountain, breaking those rocks is one of the main engineering challenges that we face."
San Andreas fault
After several field trips to Red Mountain and a series of laboratory tests, Maher and her co-workers concluded that tectonic forces played a crucial role in creating the magnesite deposits.
"To unlock the secrets of these deposits, we needed to find clues about both the mineralization process and the geologic history of the area," del Real said.
California's infamous San Andreas fault lies less than 40 miles west of Red Mountain. The fault formed about 29 million years ago, creating a large gap between the Earth's crust and the hot mantle below. The gap allowed heat to rise to the surface, raising the temperature of the water and liquid CO2 trapped in the ultramafic rocks.
|Contact: Mark Shwartz|