Quartz geochemical constraints on fluid evolution during low- to medium-temperature hydrothermal Sb and Au mineralization

Hydrothermal systems related to antimony (Sb) and gold (Au) ores form under low- to medium-temperature conditions (150−350 °C) and are often associated with major ore deposit belts. Ongoing debate surrounds the characteristics of ore-forming fluids, which are influenced by fluid sources, fluid-rock reactions, and evolutionary processes. Trace elements in quartz are critical for understanding fluid evolution in magmatic-hydrothermal systems (e.g., porphyry-epithermal deposits). This study analyzed trace elements in quartz from 43 Sb and Au deposits worldwide, focusing on low- to medium-temperature conditions. The deposits included Mesozoic Sb belts, Carlin-type and intrusion-related Au provinces in China, and late Paleozoic Sb-Au deposits in Europe. The findings reveal that Ti-Al geochemical diagrams indicate distinct affinities for the host rocks. Specifically, systems hosted by igneous rocks display elevated Ti/Al ratios (>0.005), whereas those hosted by sedimentary rocks exhibit lower ratios (<0.005). Metamorphic rock−hosted systems are best characterized by Sb-As plots and a ternary diagram involving (Ge + As)−Ti × 5−Sb. The observed relationships between Sb and As suggest that trends in Sb mineralization are more closely aligned with metamorphic rock−hosted systems, whereas trends in Au mineralization are associated with igneous rock−hosted systems in the current dataset. Sedimentary rock−hosted systems show quartz trace-element trends indicative of both Sb and Au mineralization. The Li-Al trends further highlight the distinct fluid evolution associated with Sb and Au mineralization, particularly in vein-type Sb, intrusion-related Au, and Carlin-type Au deposits. Variations in trace elements within quartz are attributed to compositional changes induced by cooling. Our results demonstrate that the trace-element signatures identified in quartz provide new insights into the evolution of fluids in low- to medium-temperature hydrothermal Sb and Au systems.