Characteristics of Grade and Resource of Sediment and Metasediment-hosted Copper-cobalt Deposits and Their Exploration Significance
Sediment and metasediment-hosted copper-cobalt deposits play an important role in global Co and Cu resources,with Co reserve exceeding 48％of the world's cobalt reserves and production accounting for over 68％of the world.The Cu reserve accounts for 20％of the world,second only to porphyry copper.The types of host rock for the copper-cobalt deposits are various,and few studies have been conducted on the characteristics and controlling factors of distribution,grade,and resource of the copper-cobalt deposits in different host rocks.Statistical analysis on the grade and resource data of the 98 collected sediment and metasediment-hosted copper-cobalt deposits on land were conducted.The copper-cobalt deposit on global land can be further subdivided into four types,including breccia-type,shale-type,sandstone-type and metasediment-type.The deposits are mainly distributed in Democratic Republic of Congo(DRC)and Zambia in Central Africa,followed by China,the United States,Finland,and Australia.The breccia-type deposits are characterized by higher Co and Cu grades,and the deposits with abnormally high Co and Cu resources are mainly breccia-type.The sandstone-and shale-type deposits are generally characterized by lower Co grades,and the shale-type deposits have typically high Cu/Co ratios.The metasediment-type deposits are usually characterized by lower Cu grades,Cu/Co ratio,and Co and Cu resources.The grade,Cu/Co ratio,and resource characteristics of sediment and metasediment-hosted cobalt copper deposits are mainly influenced by metal source and multi-stage hydrothermal fluid activities.The supernormal enrichment of Cu and Co is the result of multiple factors(such as mafic-ultramafic rocks,low grade Cu and Co mineralization,Co-rich shale and late transformation).The low Cu grade and resource of metasediment-type deposits may be attributed to significant geochemical dispersion during Cu activation and migration.The mismatch between the relatively widespread distribution and low resources of sediment and metasediment-hosted copper-cobalt deposits in China is prominent,which may indicate that there is still significant potential for mineral exploration.The future exploration of sediment and metasediment-hosted copper-cobalt deposits should focus on high grade blind deposits.
sediment and metasediment-hosted depositcopper-cobalt depositgradeCu/Co ratiometal sourcesupernormal enrichmentmineral explorationblind deposit
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