Classification of host rock formation,metallogenic model,and exploration of orogenic gold deposits
The term"orogenic gold deposits"refers to epigenetic gold-vein systems that are formed during orogeny and are controlled by both structural features and rock composition.These deposits are considered the most significant type of gold exploration globally.Based on the different types of host rocks,orogenic gold deposits can be classified into four main types:greenstone-hosted(including greenschist,BIF,and granite-gneiss subtypes),turbidite-hosted,carbonate rock-hosted,and hypabyssal intrusion types.Together,they constitute the clan of orogenic gold deposits.Among these different types,there are close temporal-spatial associations and genetic relations,making them potential indicators for mutual prospecting.The greenstone assemblage and turbidite sequenceare particularly noteworthy due to their high gold abundance.They not only serve as host rock series but also act as important source beds.The occurrence of multiple types of orogeny initiates and drives extensive regional fluid activities,leading to the formation of orogenic gold provinces or giant metallogenic belts.The superposition of magmatic fluids and the"heat engine effect"play crucial roles in the formation of super-large gold deposits.Acrustal continuous metallogenic model can be constructed by combining regional fluids from multiple sources with magmatic fluid.This model emphasizes the significance of multi-cycle orogenic processes in the formation of orogenic gold deposits.The combination of"fertile source rock,shear deformation zone,and hypabyssal intrusion"serves as the selection criterion for targeting large-scale gold systems.This approach is beneficial for acquiring exploration licenses with significant prospecting potential.Geochemical anomaly assessment and drill-tracing laterite supergene enrichment are effective methods for discovering the main ore bodies.These methods are particularly suitable for large-scale open-pit mining.The orogenic gold mining area exhibits significant potential for deep prospecting(depth＞300 m).The main targets for such exploration are large tonnage and high-grade ore shoots with extensive down-plunge extents formed during the hydrothermal channel phase.
orogenic gold deposithost rock formationmetallogenic systemore-forming fluidgold deposit exploration
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