Systematic microthermometric measurements of fluid inclusions in the PGE-polymetallic deposits hosted in the Lower Cambrian black rock series in southern China were performed, and the results suggest: (1) there exist ...Systematic microthermometric measurements of fluid inclusions in the PGE-polymetallic deposits hosted in the Lower Cambrian black rock series in southern China were performed, and the results suggest: (1) there exist two types of fluid inclusions. TypeⅠis of NaCl-H-2O system with low-medium salinity, and its homogenization temperatures (T-h) and salinities are {106.9}-{286.4℃} and ({0.8}-{21.8}) wt%NaCl eq. respectively; TypeⅡ is of CaCl-2-NaCl-H-2O system with medium-high salinities, and its homogenization temperatures and salinities range from {120.1℃} to {269.6℃} and ({11.4}-{31.4}) wt%NaCl eq., respectively. The typeⅡ fluid inclusions have been discovered for the first time in this kind of deposits; (2) two generations of ore-forming fluids were recognized. Characteristics of fluid inclusions in the PGE-polymetallic ores and carbonate-quartz stockworks in the underlying phosphorites are almost of no difference, they may represent ore-forming fluids at the main metallogenic stage. The peak value of homogenization temperature of those fluid inclusions is about 170℃, while their salinities possess a remarkable bimodal distribution pattern with two peak values of (27-31) wt%NaCl eq. and (4-6) wt%NaCl eq. On the contrary, fluid inclusions in the carbonate-quartz veins in the hanging wall may represent ore-forming fluids at the post-metallogenetic stage. The homogenization temperatures and the peak values of salinities are mostly 130-170℃ and (12-14) wt%NaCl eq., respectively; (3) nobel gas isotopic composition analyses in combination with the microthermometric measurements of fluid inclusions suggest that the ore-forming fluids at the main metallogenetic stage were probably derived from mixing of basinal hot brines with the CaCl-2-NaCl-H-2O system and seawater with the NaCl-H-2O system; (4) in the Early Cambrian, the basinal hot brines were trapped in the Caledonian basins, which were distributed along the southern margin of the Yangtze Craton, and where giant thick sediments were accumulated, and 展开更多
文摘Systematic microthermometric measurements of fluid inclusions in the PGE-polymetallic deposits hosted in the Lower Cambrian black rock series in southern China were performed, and the results suggest: (1) there exist two types of fluid inclusions. TypeⅠis of NaCl-H-2O system with low-medium salinity, and its homogenization temperatures (T-h) and salinities are {106.9}-{286.4℃} and ({0.8}-{21.8}) wt%NaCl eq. respectively; TypeⅡ is of CaCl-2-NaCl-H-2O system with medium-high salinities, and its homogenization temperatures and salinities range from {120.1℃} to {269.6℃} and ({11.4}-{31.4}) wt%NaCl eq., respectively. The typeⅡ fluid inclusions have been discovered for the first time in this kind of deposits; (2) two generations of ore-forming fluids were recognized. Characteristics of fluid inclusions in the PGE-polymetallic ores and carbonate-quartz stockworks in the underlying phosphorites are almost of no difference, they may represent ore-forming fluids at the main metallogenic stage. The peak value of homogenization temperature of those fluid inclusions is about 170℃, while their salinities possess a remarkable bimodal distribution pattern with two peak values of (27-31) wt%NaCl eq. and (4-6) wt%NaCl eq. On the contrary, fluid inclusions in the carbonate-quartz veins in the hanging wall may represent ore-forming fluids at the post-metallogenetic stage. The homogenization temperatures and the peak values of salinities are mostly 130-170℃ and (12-14) wt%NaCl eq., respectively; (3) nobel gas isotopic composition analyses in combination with the microthermometric measurements of fluid inclusions suggest that the ore-forming fluids at the main metallogenetic stage were probably derived from mixing of basinal hot brines with the CaCl-2-NaCl-H-2O system and seawater with the NaCl-H-2O system; (4) in the Early Cambrian, the basinal hot brines were trapped in the Caledonian basins, which were distributed along the southern margin of the Yangtze Craton, and where giant thick sediments were accumulated, and
