Petrogenesis of a zirconolite-bearing Mediterranean-type lamproite from the Peruvian Altiplano (Andean Cordillera)

Phlogopite lamproites occur in the Inner Arc Tectono-Magmatic Domain of the Eastern Altiplano (southern Peru, Andean Cordillera), a geotectonic setting characterizing lamproites at destructive plate margins. One sample free from contamination by crustal felsic melts displays many diagnostic features of «Mediterranean» lamproites as regards mineral assemblages and the bulk-rock composition [56.6 wt.% SiO2, 12.9 wt.% Al2O3, K2O/Al2O3<0.8, MgO<8 wt.%, CaO<3.5 wt.%, very strong LILE enrichment (La/YbN=27) and Sr, Nb, Ta and Ti negative anomalies (Sr/NdN=0.49, La/NbN=0.38)]. In thin sections, the rock shows a volumetrically dominant fluidal groundmass (82 vol.%) enclosing 1–3 mm olivine-rich polycrystalline aggregates [Mg–Ni-rich olivine, (88