Hydrothermal alteration and mineralization in Santo Domingo Sur Iron Oxide (-Cu-Au) (IOCG) deposit, Atacama Region, Chile

The Santo Domingo Sur (SDS) deposit, near Diego de Almagro, is a recent IOCG discovery in the Chilean Iron Belt (018) containing 486 Mt at 0.32% Cu, 0.043 ppm Au and 27.2% Fe. Recent field work and petrographic studies have refined the main geological features and provided insight into the time-space evolution of the hydrothermal system. SDS is hosted by volcanic and volcaniclastic rocks correlated with the Early Cretaceous Punta del Cobre Formation and the Bandurrias Group, and a limestone-bearing volcanic section that may belong to the Chanarcillo Group. These rocks are intruded by variably altered sills and small stocks. Mineralization occurs as chalcopyrite-bearing semi- to massive specularite and magnetite mantos with minor veins and breccias. The mantos zone forms an outer rim of specular-hematite over a magnetite-rich core. Hydrothermal zoning goes from distal, low-moderate-T Na(Ca) associations, recognized in the upper levels of the orebody, towards proximal and moderate-T Na(Ca) minerals in the deeper parts of the deposit. Nearby garnet-magnetite-rich skarns surround oligoclase-actinolite(-scapolite-titanite) altered quartz diorites. SDS has similarities with the Candelaria / Punta del Cobre and Mantoverde districts.