Southwest Indian Ridge hydrothermal mineralization and its geological and geochemical studies

Title: Southwest Indian Ridge hydrothermal mineralization and its geological and geochemical studies
　　Author: Cao Hong
　　Degree-granting units: Ocean University of China
　　Keywords: SWIR;; basalt;; hydrothermal deposition;; mineralization;; Geology and Geochemistry
　　Summary:
　　In this paper, Southwest Indian Ridge (SWIR), and hydrothermal deposits in different regions basalt samples for the study, high-precision ICP-AES/MS, X-ray diffraction, electron microscopy and other means of experimental tests, the samples mineralogy, Strong magnets petrology, geochemical characteristics of the study, in order to explore the Southwest Indian Ocean Ridge hydrothermal mineralization, source materials and other scientific issues, to look for hydrothermal deposits provide a theoretical basis. The study results obtained in the following areas:
　　Basalt trace element ratios of the study area showing normal mid-ocean ridge basalt (N-MORB) nature, but different from the typical N-MORB, also include "MORB" type of magma and magma ocean island two components. The spider diagrams basalt partition curves reflects the depleted mantle source basalt geochemical characteristics. Large ion lithophile elements K, Rb and Ba slight enrichment, Ba has a significant positive anomalies, Sr show negative anomalies, and there Nb and some Ti losses, indicating that the basalt formation may be subject to a land-based sources of contamination .
　　Show LREE enrichment relative to REE, HREE loss of REE distribution patterns of variation in La-La/Sm map, La / Sm and La increased simultaneously, indicating that the SWIR basaltic lava rock is mainly affected by partial melting control.
　　From 69.59 ° E near the overflow area of ​​hydrothermal sulfide (AIR1 and AIR2) for the collapse of the black smoker sulfide. AIR1 mainly by pyrite, marcasite, and chalcopyrite form, is in - high-temperature mineral assemblages, the relative enrichment of Co and Ni, that chalcopyrite at high temperatures (> 300 ℃) precipitate formed. AIR2 mainly by pyrite, marcasite and gypsum composition, reflecting a medium - low-temperature mineral assemblages. 49.64 ° E near the sulfur oxides ISUl by the lepidocrocite, chalcopyrite and minor pyrite and marcasite formed. ISU2 from 50.46 ° E near the altered peridotite, magnesium and boron by the water-rich rock, Lee serpentine, and manganese oxide and iron alum mineral composition. Hydrothermal white chimney ISU4 and ISU5 from near 51 ° E, mainly calcite, whose temperature hydrothermal fluids in - cold.
　　Between Cu and Fe sulfide hydrothermal significant positive correlation reflects the relationship between mineral assemblages; As, Sr and Ag elements are greater than the correlation coefficient between 0.85, indicating that they are in the process of hydrothermal mineralization has experienced similar geochemical processes; Pb and Zn are determined http://www.chinamagnets.biz/ by the content of Au and Ag; Ag, As and Pb, which have a high correlation between, may indicate that the low-temperature re-activation.
　　REE potential of hydrothermal sulfide partition curves show a clear positive Eu anomaly and LREE enrichment, the distribution patterns of the major inherited characteristics of rare earth elements in hydrothermal fluids. White high REE content of hydrothermal chimney, LREE enrichment, negative Eu anomalies may significantly shows that the relative reduction of the ore-forming environment.
　　Degree Year: 2010