Scientists Uncover the Secrets of, Tanzania’s Oldoinyo Lengai Volcano

May 7, 2009

(ChattahBox)—Scientists have long puzzled at the rare carbon-based lava erupting out of Tanzania’s Oldoinyo Lengai Volcano, flowing down the mountain like fluid motor oil. Typical lavas from active volcanoes contain lavas composed of high levels of silica, which raises the melting point to above 1652°F. However, the unusual carbon lavas from the Oldoinyo Lengai Volcano reach a melting point at a low temperature of just 1004°F.

The lavas from the Oldoinyo Lengai contain almost no silica and greater than 50 percent carbonate minerals, which are called carbonatites.

To finally solve the mystery of the only active volcano in the world to have carbon-based lavas, a team of scientists from the University of New Mexico, Scripps Institution of Oceanography at UC San Diego and Centre de Recherches Petrographiques et Geochimiques in Nancy, France, decided to go on a dangerous journey deep within the recesses of the active volcano.

This scientific journey was akin to Jules Verne’s compelling tale of “A Journey to the Center of the Earth,” well not really; their expedition didn’t include prehistoric mastodons, giant mushrooms or a subterranean ocean.

But the present day explorers did climb inside the active Oldoinyo Lengai to collect valuable volcanic gas samples, which proved invaluable in deciphering the reason behind the high concentration of carbon in its lava. The researchers also were able to collect uncontaminated samples during a 2005 eruption.

After analyzing the gas samples taken from the Oldoinyo Lengai, the team of scientists discovered that a small occurrence of partial melting of minerals in the earth’s upper mantle is responsible for the source of the rare carbon-derived lava erupting from the volcano.

The scientists came to this conclusion, based on the location of the Oldoinyo Lengai in a rift valley over a mid-ocean ridge after an analysis of the samples showed that the carbon is derived directly from the upper mantle below the East African Rift.

Geochemist Bernard Marty, said, “these extremely bizarre lavas and their parent magmas, nephelinites, were produced by melting of a typical upper mantle mineral assemblage without an extreme carbon content in the magma source.”

Scientists now know that carbon based lavas can be produced from a very low melt fraction of 0.3 percent or less in the earth’s mantle.

The interesting study is available in the May 7 issue of the Nature Journal.

Source


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One Response to “Scientists Uncover the Secrets of, Tanzania’s Oldoinyo Lengai Volcano”

  1. Ol Doinyo Lengai-Volcanologist say Mt. is behaves like it is already on the sea floor - Mashada Forums on May 14th, 2009 11:03 am

    […] 10:03 AM after analyzing the gas samples taken from the oldoinyo lengai, the team of scientists discovered th… alchemy in tanzania? gas becomes solid at surface of oldoinyo lengai volcano – us news and world […]

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