Hydrothermal Mineralization And Geological And Geochemical Characteristics Of SWIR

The basalts and hydrothermal deposits samples we study are recovered from the different regions of the Southwest Indian Ridge (SWIR).We get the mineralogy,Petrology and geochemistry characteristics by high performance ICP -AES/MS,X-Ray Diffraction and Electronic Microscope, to discuss hydrothermal mineralization,material sources and other scientific problems and get the theory for exploring the submarine hydrothermal deposits. We get the results as following:Trace element ratios of basalts showing the similar characteristics to the Normal Mid-Ocean Ridge Basalt (N-MORB), but different from the typical N-MORB, while including two components:"MORB"-type magma and Ocean Island magma. The spider diagram shows the depleted-mantle magma source. Slight rich in LILE(K, Rb, and Ba), poor in Nb and parts of Ti, Ba significant positive anomalies, Sr shows negative anomalies, which might indicate the contamination of terrestrial. The REE shows the relative enrichment of LREE to HREE. La/Sm and La simultaneous increase, indicating that the basalt mainly control by partial melting.AIR1 and AIR2 are the collapsed black chimneys sulfide, near the 69.59°E. AIR1 is middle-high temperature mineral assemblages, dominated with pyrite, marcasite and chalcopyrite. Relative enrichment of Co and Ni, indicating that chalcopyrite precipitate at a high temperature (> 300℃). AIR2 is medium-low temperature mineral assemblages, dominated with pyrite, marcasite and gypsum. ISU1 is the sulfide oxides, mainly consist of lepidocrocite,chalcopyrite and pyrite, sampling from the 49.64°E. ISU2 is birbirite, near 50.46°E, mainly consist of kurnakovite,lizardite,manganese oxide and iron alum minerals. Hydrothermal white chimneies ISU4 and ISU5 from 51°E around, mainly composed of calcite, the temperature of hydrothermal fluids is middle-low temperature.Cu and Fe of the sulfides showing significant positive correlation, reflects the relationship of mineral assemblages; The correlations between As,Sr and Ag were higher than 0.85, indicating that they have undergoing the similar geochemical processes in hydrothermal mineralization; Pb and Zn pespectively determines the content of Au and Ag; there are significant positive correlations between Ag,As and Pb, which might indicate remobilization under lower temperature conditions.The sulfide samples are characterized by significant positive Eu anomaliesand the enrichment of LREE relative to HREE, inheriting the characteristics of hydrothermal fluids. The REE contents are high in white chimneys rich in calcile, chondrite-normalized pattern shows LREE enrichment and negative Eu anomalies may indicate the relative reductive environment.