Title: MINERAL CHARACTERISTIC OF SKARNS IN THE ANQING COPPER DEPOSIT OF ANHUI AND THEIR GEOLOGICAL SIGNIFICANCE
Abstract: Anqing copper-iron deposit is a typical skarn-type deposit along the middle and lower Yangtze River iron-copper metallogenic belt.The ore bodies located in the contact zone between Yueshan pluton and carbonate rock of Nanlinghu Formation of Lower Triassic.Skarns in exocontact zone are rich in diopside with iron-copper mineralization and skarns in internal contact zone are rich in garnet with copper mineralization.Petrographic studies show that the evolution of the copper silicon skarn in the area experienced skarn period and hydrothermal alteration period.The skarn period includes the early stage of skarn,magnetite stage and late stage of skarn,and the hydrothermal alteration period includes he early hydrothermal stage,quartz-sulfide stage and quartz-carbonate stage.Massive chalcopyrite mineralization mainly occurred in quartz-sulfide stage.Mineralogical studies suggest that the garnets are andradite,granular garnet of the early stage of skarn develops rhythm zoning with oscillation of FeO and Al2O3 content.Compared with granular garnet,the vein-shape garnet of late stage skarn is higher in andradite end-member.The granular pyroxene in the early skarn stage is diopside with ring structure,its MgO content gradually reduced from the core to the edge,while FeO content gradually increased.Vein-shape pyroxene in the late skarn stage is hedenbergite.In spatial,from exocontact zone to internal contact zone,MgO content of pyroxene and Al2O3 content of garnet is reduced,while FeO content of both pyroxene and garnet are increased.Petrography,mineralogy,combined with the existing geochemical research show that skarn of Anqing copper-iron deposit are magmatic-hydrothermal contact metasomatic origin.Mg came from carbonate rocks,migrated from exocontact zone to internal contact zone.Fe came from magmatic hydrothermal,migrated from internal contact zone to exocontact zone.Due to the change of temperature and pressure conditions in magnetite stage,Fe precipitated and enriched in the exocontact zone in the form of magnetite.
Publication Year: 2012
Publication Date: 2012-01-01
Language: en
Type: article
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Cited By Count: 1
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