Volcanic Rocks: Boundaries from experimental petrology

Abstract

Volcanoes are the surface manifestation of the process of chemical differentiation of the Earth. Experimental petrology calibrates the conditions for partial melting of various rocks, and defines the compositions of melts derived by partial melting and the paths of crystallization of magmas under varied conditions. Experimental results provide phase boundaries that constrain the sites of partial melting in the Earth's interior, given sufficient information about the source materials at depth and the geotherm as a function of tectonic environment and time. The petrogenesis of basalts requires comprehension of the phase relationships for mantle peridotite as well as the derivative basalts. The effect of volatile components C-O-H on melting elucidates the origin of nephelinites associated with hot-spot oceanic basalts, and the origin of kimberlites, nephelinites and carbonatites in cratonic regions. At convergent plate boundaries, the devolatilization of subducted oceanic crust influences magma generation in overlying mantle wedge and continental crust, preludes to the eruption of andesites and rhyolites. Experiments on hybridization are applicable to the complex interactions between magmas from various sources that occur in this environment.