A new style of Ni-Cu mineralization related to magmatic breccia pipes in atranspressional magmatic arc, Aguablanca, Spain

The Aguablanca deposit represents a new style of magmatic Ni-Cu mineralizat ion in discordant sulfide-rich pyroxenitic breccia pipes. The orebody is ho sted by Variscan calc-alkaline diorites and gabbros which intruded during a n oblique subduction/collision event. Transpressional-transtensional left-l ateral structures facilitated the intrusion of primitive magmas to shallow depths in the crust. a two-stage genetic model is proposed. In the first st age, a transitional deep magma chamber formed. The primitive magma interact ed at depth with wall rocks, resulting in extensive crustal contamination, concomitant sulfide magma immiscibility and settlings of orthopyroxene-, cl inopyroxene-, and sulfide-rich cumulates to form a layered magmatic complex . Geochemical and mineralogical evidence, including the virtual disappearan ce of olivine, heavy S-34 values (7.4 parts per thousand), distinctive Nd, Sr and Pb signatures, high Au contents, and the presence of spinel and grap hite indicates a major interaction with the upper crust, probably with pyri te-rich carbonaceous slates of Late-Proterozoic age. the second stage was r elated with the emplacement of residual calc-alkaline gabbroic to noritic m elts and the development of an intrusive breccia containing fragments of th e consolidated layered complex rocks and associated disseminated to massive sulfides.