Study on fluid inclusions and features of ore-forming fluids of Diakha gold deposit,Mali,West Africa

作者：Yassa Konare,WANG Keyong,WANG Zhigao

摘要：The Diakha gold deposit is located in the southeastern margin of the highly prospective/productive Paleoproterozoic(Birimian)Kédougou-Kéniéba Inlier.Gold mineralization is closely associated with a narrow,sub-vertical,NE-trending shear corridor.The corridor is to the east of a sinistrally reactivated D1 west-dipping fault,which emanated from SMSZ(D2 reverse-sinistral regional structure).The mineralization is hosted by fine-grained sandstone and breccias units associated with a moderate to strong hydrothermal alteration,which is dominated by albitization,carbonization,silicification,hematization,and chloritization.Diakha field data and laboratory analysis suggest the existence of two main stages of hydrothermal mineralization,namely stage I and stage II.[JP2]Stage I is of a breccias type of mineralization and represents the major gold bearing stage.[JP]It isassociated with hematite+calcite+ankerite/dolomite and quartz pervasive alteration,controlled by the predominantly brittle-ductile NNE to NE-shearing structures of the main deformation event D2.Stage II is represented by the second minor hydrothermal episode,showing local quartz-tourmaline and tremolite alteration which is structurally controlled by the dipping S3 cleavage formed during D3 deformation.Petrographic and microthermometric studies of fluid inclusions from quartz veins reveal the presence of early dominant carbonic CO 2-pure and aqueous-carbonic CO 2-rich(LCO 2+VCO 2±H 2O)in stage I.The exclusively aqueous H 2O+NaCl±CO 2 fluid inclusions(L-type)are observed in stage II.Interpretation shows that the ore-forming fluids originated from a homogeneous H 2O-CO 2 fluid during phase separation,with trapping temperatures of 250℃to 280℃and low salinity(<6 wt%NaCl equiv),indicating an estimated trapping pressure for the deposit between 610 to 800 bars.

发文机构：College of Earth Sciences

关键词：Kédougou-KéniébaInlierDiakhadeposithydrothermalALTERATIONAu-mineralizationfluidINCLUSIONS

分类号： P[天文地球]