Sanidine holocrystalline ejecta from central Sabatini Volcanic District, Latium (Italy). II. Intergranular ejecta and minerogenetic deductions

The sanidine holocrystalline ejecta with intergranular texture from the central Sabatini Volcanic District contain high-T feldspars, out-of-equilibrium K- and Na- Ca-feldspar, and two pyroxene generations formed at different depths, as well as many mineral phases which indicate high f(H2O) and/or f(O2). A simple evolution model by fractional crystallization, in a plutonic or hypoabissal domain, has been derived from the mineralogical assemblages present in both the isotropic and intergranular type of ejecta. The intergranular type, the crystallization of which began at deeper levels than the isotropic one, underwent multiple pyroxene-liquidus re-equilibrations during a quick magma ascent to shallower levels.