The Huayuan Pb-Zn ore district in China,located in western Hunan Province,is a giant carbonate-hosted Pb-Zn ore district.The source of ore-forming brines in this ore district remains poorly constrained.Whether the hig...The Huayuan Pb-Zn ore district in China,located in western Hunan Province,is a giant carbonate-hosted Pb-Zn ore district.The source of ore-forming brines in this ore district remains poorly constrained.Whether the highly saline brines are derived from evaporated seawater or dissolved evaporates continues to be intensely debated.Carbonate minerals associated with Pb-Zn mineralization haveδ^(13)CV-PDB andδ^(18)OV-SMOW values ranging from−5.55‰to+1.35‰(mean value of−0.69‰;n=14)and+16.28‰to+25.05‰(mean value of+20.22‰;n=14),respectively.This indicates that carbonate minerals are dominantly formed from dissolved ore-hosted carbonate rocks.Theδ^(34)S values of sulfides range from+20.2‰to+36.8‰,with an average value of+30.0‰(n=27).These results suggest that sulfur is predominantly derived from the thermochemical sulfate reduction of marine sulfate.The crush-leach analyzed solute data of fluid inclusions in sphalerite show the ore-forming fluids have Cl/Br molar ratios range from 118 to 384,and Na/Br molar ratios from 39 to 160(n=8).These Cl/Br ratios of hydrothermal fluid are much lower than those of seawater(657 to 564),but are consistent with bittern brines through early halite precipitation.We propose that ore-forming fluids are mainly derived from evaporitic basin brines,which leached base metals from the basement and/or country rocks.The brine then migrated to the basin margins through clastic rocks of basement and then precipitated sulfides by thermochemical sulfate reduction.展开更多
The super large Pb Zn deposit at Fankou is very complex in metallogenic mechanism. Syngenetic brine sedimentation, hot submarine spring eruption—accumulation, syngenetic sedimentation—vadose brine replacement had be...The super large Pb Zn deposit at Fankou is very complex in metallogenic mechanism. Syngenetic brine sedimentation, hot submarine spring eruption—accumulation, syngenetic sedimentation—vadose brine replacement had been supposed as the genetic models before. Under these models, syngenetic mineralization should be dominant in ore formation. However, a series of geological and geochemical properties investigated by authors of this paper are contrary to these models. Therefore, the authors here suggest that this deposit is a typical polygenetic compound ore deposit which share the properties of multistages of geotectonic evolution, multifactors of mineralization control, multisystem of material derivation of mineralization, multimodes of mineralization and multitypes of genesis.展开更多
基金financially supported by the Geological Survey Program of China Geological Survey Bureau(Grant No.12120114016601)。
文摘The Huayuan Pb-Zn ore district in China,located in western Hunan Province,is a giant carbonate-hosted Pb-Zn ore district.The source of ore-forming brines in this ore district remains poorly constrained.Whether the highly saline brines are derived from evaporated seawater or dissolved evaporates continues to be intensely debated.Carbonate minerals associated with Pb-Zn mineralization haveδ^(13)CV-PDB andδ^(18)OV-SMOW values ranging from−5.55‰to+1.35‰(mean value of−0.69‰;n=14)and+16.28‰to+25.05‰(mean value of+20.22‰;n=14),respectively.This indicates that carbonate minerals are dominantly formed from dissolved ore-hosted carbonate rocks.Theδ^(34)S values of sulfides range from+20.2‰to+36.8‰,with an average value of+30.0‰(n=27).These results suggest that sulfur is predominantly derived from the thermochemical sulfate reduction of marine sulfate.The crush-leach analyzed solute data of fluid inclusions in sphalerite show the ore-forming fluids have Cl/Br molar ratios range from 118 to 384,and Na/Br molar ratios from 39 to 160(n=8).These Cl/Br ratios of hydrothermal fluid are much lower than those of seawater(657 to 564),but are consistent with bittern brines through early halite precipitation.We propose that ore-forming fluids are mainly derived from evaporitic basin brines,which leached base metals from the basement and/or country rocks.The brine then migrated to the basin margins through clastic rocks of basement and then precipitated sulfides by thermochemical sulfate reduction.
文摘The super large Pb Zn deposit at Fankou is very complex in metallogenic mechanism. Syngenetic brine sedimentation, hot submarine spring eruption—accumulation, syngenetic sedimentation—vadose brine replacement had been supposed as the genetic models before. Under these models, syngenetic mineralization should be dominant in ore formation. However, a series of geological and geochemical properties investigated by authors of this paper are contrary to these models. Therefore, the authors here suggest that this deposit is a typical polygenetic compound ore deposit which share the properties of multistages of geotectonic evolution, multifactors of mineralization control, multisystem of material derivation of mineralization, multimodes of mineralization and multitypes of genesis.
