Co-chief scientists Jonathan Snow from UH and Kathryn Gillis from University of Victoria in Canada led a team of 30 researchers from around the world on the 10-million-dollar-expedition, finding a few surprises upon penetrating the lower crust of the Pacific.
Traveling aboard the Integrated Ocean Drilling Program Expedition 345 to the Hess Deep in the Pacific Ocean, the scientific voyagers recovered core sections of lower crustal rocks, called gabbros, that formed more than two miles beneath the sea floor.
The two-month expedition, aboard the drilling vessel JOIDES Resolution, confirmed for the first time the widespread existence of layered gabbros in the lower crust.
By studying thin slices of the gabbros under polarizing microscopes, the scientists identified substantial amounts of the mineral orthopyroxene, a magnesium silicate that was thought to be absent from the lower crust.
A third surprise, Snow says, casts doubt on one of the main theories of the construction of the lower ocean crust. It involved the mineral olivine, also a magnesium silicate.
This mineral is known to grow in delicate crystals sometimes found in layered intrusions on land, but never expected in the ocean crust. This is because the separation of the tectonic plates was thought to deform the magma like play dough in a partially molten state that would have broken them up.
The research has been published in the journal Nature.
--ANI (Posted on 04-12-2013)