Biogeochemical formation of metalliferous laminations in surficial environments

摘要: Finely laminated (cm–μm scale) metalliferous precipitates are widespread in the surficial environment, especially around mineral deposits and reflect biogeochemical processes that can pervade near-surface environments on a larger scale. Examples this paper involve of transition metals Fe, Cu Mn with minor Co, Ni, V Zn; metalloids As Sb; authigenic Au. Mobility re-precipitation driven primarily by geochemical disequilibrium, respect to pH redox states, arises from complex interactions between biological processes, geological variations surrounding environment. Different degrees chemical disequilibrium arise small spatial scales time days millennia. Interactions biota, waters rocks these settings affect environments. Sulfur- iron-oxidising bacteria common agents associated sulfide-bearing lithologies, but localised reductive also develop, leading gradients state differential metal mobility. In general, there is commonly separation Fe-rich those Mn, other follow rather than Fe. Metalloids Sb have strong affinity for Fe under oxidising conditions, not more reducing conditions. However, parageneses preclude prediction finer formation details. The textures, species, associations within likely be encountered all facets deposit development: initial exploration activity locations, mining shallow portions orebodies, supergene zones, downstream environmental management discharging waters.