The minerals constituting the Earth’s upper mantle are nominally anhydrous silicates (NAMs: olivine, pyroxenes, garnet, spinel), but they can contain hydrogen as a trace element, decorating point defects in their crystalline structure. Experimental petrology and mineralogy have quantified the maximum concentration under a large range of compositional and thermodynamic conditions, but systematic studies on the hydrogen concentration in minerals from mantle-derived rocks have only recently been carried out. Here, we will present a compilation the distribution of hydrogen in upper mantle peridotite xenoliths, from which several conclusions can be drawn. We will also explore the consequences on the viscosity of Earth’s mantle lithosphere.
