Measuring the oxidation of iron in the magma that build the oceanic floor

What is it about?

Mid-ocean ridge basalts (MORBs) are formed by partial melting of the upper mantle, and their continuous eruption at mid-ocean ridges build the oceanic floor. As such, they actually represent the largest volume of magma erupted on Earth. Besides, their study provide us information about the Earth upper mantle. A particularly important parameter is the oxygen fugacity at MORBs' source, because knowing this parameter allows constraining the conditions of pressure and temperature, and, in turn, models of the oceanic floor accretion.

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Photo by Richard Gatley on Unsplash

Photo by Richard Gatley on Unsplash

Why is it important?

Small errors on the estimates of pressure and temperature in the upper mantle can generate large errors on our understanding of the oceanic floor accretion mechanism. This is why it is necessary to have the most accurate knowledge of such parameters, and, hence, of oxygen fugacity conditions. Measuring the oxidation state of iron in MORBs allow one to determine the oxygen fugacity at their source. Several methods are available to perform such measurements, but have different advantages and drawbacks. In this publication, we applied Raman spectroscopy to measure the oxidation state of iron. This technic is non-destructive, quick, easy to perform, and inexpensive, and allowed to measured an oxidation of iron in agreement with the latest estimates from other methods.

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