Carlin-type gold deposits host gold in arsenian pyrite, but core-rim pyrite growth mechanisms remain unclear. This study integrates micro-/nano-scale analyses of pyrite from Chinese deposits. Gold-poor cores formed pre-ore, while gold-rich rims crystallized during mineralization. Crystallographic alignment between cores and rims (via EBSD/TEM) confirms epitaxial growth on (010) facets, minimizing surface energy. This challenges replacement models, emphasizing substrate-guided crystallization.
Fluid-carbonate reactions drove rim formation. Ore fluids dissolving Fe-bearing carbonates released Fe²⁺, triggering pyrite nucleation. Pre-existing cores served as low-energy substrates, enabling epitaxial overgrowths. Polycrystalline rims on framboidal cores and rare misoriented grains reflect fluctuating supersaturation. Such substrate dependence explains why precursor pyrite is critical for efficient gold enrichment in low-temperature hydrothermal systems.
Epitaxial growth links pyrite crystallization to gold endowment. Pre-ore pyrite provided both Fe²⁺ (via carbonate dissolution) and templates for rim development, favoring high-grade mineralization in reactive carbonate hosts. These insights redefine genetic models, emphasizing lithology and precursor textures as exploration guides for Carlin-type and analogous gold systems globally. The work entitled “Consistent crystal orientation of core and rim pyrites indicates an epitaxial growth of rim in Carlin-type gold deposits” was published on Geoscience Frontiers (published on Nov 17, 2024).
DOI: 10.1016/j.gsf.2024.101966