The Arsenic Fault-Pathfinder: A Complementary Tool to Improve Structural Models in Mining

Abstract

In a mining operation, the structural model is considered as a first-order data required for planning. During the start-up and in-depth expansion of an operation, whether the case is open-pit or underground, the structural model must be systematically updated because most common failure mechanisms of a rock mass are generally controlled by geological discontinuities. This update represents one of the main responsibilities for structural geologists and mine engineers. For that purpose, our study presents a geochemically-developed tool based on the tridimensional (3-D) distribution of arsenic concentrations, which have been quantified with a very high-density of blast-holes sampling points throughout an open pit operation. Our results show that the arsenic spatial distribution clearly denotes alignments that match with faults that were previously recognized by classical direct mapping techniques. Consequently, the 3-D arsenic distribution can be used to endorse the existence and even more the real persistence of structures as well as the cross-cutting relationships between faults. In conclusion, by linking the arsenic fault-pathfinder tool to direct on field fault mapping, it is possible to improve structural models at mine scale, focusing on geotechnical design and management, with a direct impact in the generation of safety mining activities.

Tracking Cobalt, REE and Gold from a Porphyry-Type Deposit by LA-ICP-MS: A Geological Approach towards Metal-Selective Mining in Tailings

“…This multistage magmatic-hydrothermal evolution is considered a critical factor that contributed to the enormous copper endowment of the Río Blanco-Los Bronces-Los Sulfatos system [9][10][11]. This system is emplaced in deformed Neogene volcanoclastic units, and its formation is linked to the evolution of the West Andean Thrust system (WATs), a west-vergence fault and thrust structure that controlled the uplift of the western margin of the Central Andes (e.g., [12,13]) (Figure 2). The main ore paragenesis consists of copper (Cu) ± molybdenum (Mo)-bearing sulfides, and for each mineralizing Teniente (95 Mt of contained copper) porphyry copper deposits, which occur in the same metallogenic belt.…”

“…This multistage magmatic-hydrothermal evolution is considered a critical factor that contributed to the enormous copper endowment of the Río Blanco-Los Bronces-Los Sulfatos system [9][10][11]. This system is emplaced in deformed Neogene volcanoclastic units, and its formation is linked to the evolution of the West Andean Thrust system (WATs), a west-vergence fault and thrust structure that controlled the uplift of the western margin of the Central Andes (e.g., [12,13]) (Figure 2). The main ore paragenesis consists of copper (Cu) ± molybdenum (Mo)-bearing sulfides, and for each mineralizing event it comprises of (i) essentially chalcopyrite (CuFeS 2 ), bornite (Cu 5 FeS 4 ), and molybdenite (MoS 2 ), accompanied mainly by pyrite (FeS 2 ) in the early stages; (ii) chalcopyrite and pyrite, accompanied by a minor proportion of chalcocite (Cu 2 S) and covellite (CuS) for the main stage case; and (iii) chalcopyrite and minor bornite, accompanied by mainly pyrite and enargite (Cu 3 AsS 4 ), as well as tennantite ((Cu,Fe) 12 As 4 S 13 ), sphalerite ((Zn,Fe)S), and galena (PbS) in the late-stage case [9][10][11].…”