Geochronology, geochemistry, and isotopic composition (Sr, Nd, Pb) of Tertiary porphyry systems in Ecuador

Resumen

This thesis presents geochronologic, geochemical, and isotopic data on Tertiary arc magmas associated with porphyry-related ore deposits in the northern Andes of Ecuador. In detail, ages on host and porphyry intrusion emplacement (U-Pb zircon) and hydrothermal alteration/mineralization (U-Pb titanite, Re-Os molybdenite) were obtained, combined with whole-rock geochemical analysis of least altered igneous rock samples. These data are discussed in a regional frame with respect to the geodynamic context. The following main conclusions apply: (1) porphyry-related ore deposits in Ecuador are mainly Miocene in age, and represent the northern extension of the Miocene metallogenic belt of northern-central Peru; (2) intrusions associated with mineralization are compositionally highly variable; a systematic association of mineralization with a specific trace element signature cannot be observed; (3) flat slab settings produce favorable exposure conditions for porphyry-related ore deposits; a systematic association of ore deposit formation and seamount chain (Carnegie Ridge) subduction is not observed.