Life-giving Rocks From A Depth Of 250 Km

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ScienceDaily: Life-giving Rocks From A Depth Of 250 Km

 

Life-giving Rocks From A Depth Of 250 Km

 

Science Daily — If our planet did not have the ability to store oxygen in the deep reaches of its mantle there would probably be no life on its surface. This is the conclusion reached by scientists at the University of Bonn who have subjected the mineral majorite to close laboratory examination. Majorite normally occurs only at a depth of several hundred kilometres under very high pressures and temperatures.

 

The Bonn researchers have now succeeded in demonstrating that, under these conditions, the mineral stores oxygen and performs an important function as an oxygen reservoir. Near the earth's surface the structure breaks down, releasing oxygen, which then binds with hydrogen from the earth's interior to form water. Without this mechanism our "Blue Planet" might well be as dry and inhospitable as Mars.

The proverbial "solid ground" under our feet is actually in constant flux. At the boundaries between the tectonic plates in what are called the subduction zones this seemingly solid ground is drawn down many hundreds of kilometres into the hot interior. As the material descends it takes with it oxygen, which is bound as iron oxide in the earth's mantle oxygen that derives from the dim distant beginnings of the universe.

Far below the earth's surface high pressures and temperatures prevail. As the mantle material melts the iron oxide undergoes a chemical metamorphosis in which its oxygen component becomes, in a sense, more reactive. Moreover, it changes its medium of transportation, now being incorporated into the exotic mineral majorite which only occurs at these depths. And, as Professor Dr. Christian Ballhaus from the Mineralogical Institute at the Bonn University explains, "The higher the pressure, the more oxygen can be stored by majorite.".

Majorite: Majorite mineral information and data.