| The Jianchaling nickel deposit is located in Lueyang County,Hanzhong City,Shaanxi Province,30 kilometers southeast of the city.It is one of the important nickel deposits in China.Due to its enrichment of and its complex geological environment,the deposit has attracted extensive attention from geologists and geologists from both domestic and abroad.This paper studied the mineralogy and geochemistry of the ultrabasic rocks of the Jianchaling nickel deposit by field geological survey sampling,combined with indoor microscope observation,electron probe and ICP-MS chemical analysis.The geological characteristics of the Jianchaling nickel deposit,the ultrabasic rock type,the structure of the ultrabasic rock microscope,the base metal sulfide mineral composition and the main trace?rare earth?elements are summarized.The main results are as follows:?1?The main nickel-bearing ultrabasic rocks of the Jianchaling nickel deposit are divided into five types:leaf serpentinite,fibrillar serpentinite,tremolitie,talc magnesitization rock,magnesitization rock.The metal minerals in the Jianchaling nickel deposit are pentlandite,pyrrhotite,pyrite,millerite,violarite,unknown nickel mineral,chalcopyrite,magnetite.The gangue minerals are serpentine,tremolite,magnesite,talc,chlorite,calcite,dolomite,mica,and quartz.The nickel oxide ore are tremolitie and magnesitization rock,the nickel sulfide ore is mainly a serpentinite.?2?Rock geochemical analysis shows that the original rocks before the alteration of ultrabasic rocks in Jianchaling nickel deposit are mafic olivine pyroxene or ferruginous peridotite;serpentinite and magnesitization rock are rich in Ni,Co,Cu and Cr,and the content of Ni in leaf serpentinite is the highest,while the total amount of rare earth elements is low,and the total amount of light rare earth elements is richer than that of heavy rare earth elements.?3?The Jianchaling nickel deposit can be divided into four metallogenic stages:pyrrhotite-pyrite-pentlandite stage,pyrrhotite-pentlandite stage,millerite-pyrite-pentlandite stage and pyrite-chalcopyrite stage.?4?The study shows that the Jianchaling nickel deposit was formed by hydrothermal reformation after the period.pentlandite-pyrrhotite-pyrite-chalcopyrite-violarite in serpentinite is an early nickel-bearing metallic sulfide mineral assemblage,while millerite-pyrite-unknown nickel mineral is a late nickel-bearing metallic sulfide assemblage.The chemical composition of pyrrhotite is used to discover the heterogeneity of pyrrhotite,indicating that the mineralization process undergoes rapid cooling.The temperature of pyrrhotite-pyrite-pentlandite stage is higher than that of pyrite-chalcopyrite stage determined by the ratio of(Fe2++Cu2+)/S2+of chalcopyrite.The Ni/Co ratio of pyrite determines that the deposit is of magmatic hydrothermal origin.?5?There are unknown nickel minerals in Nickel oxide ores.Millerite-pyrite-pentlandite mineral assemblage is a prospecting indicator for nickel oxide ores.The oxygen content of unknown nickel minerals in nickel oxide ores is positively correlated with the color depth of BSE graph.The mineral assemblage of pyrrhotite-pyrite-pentlandite is a prospecting indicator for nickel sulfide ores. |
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