The compositions of REE in quartz and pyrite from the main stage of the Laowan gold deposit in Henan Province and that in quartz from Laowan granite were determined by inductively coupled plasma-mass-spectrometry （IC...The compositions of REE in quartz and pyrite from the main stage of the Laowan gold deposit in Henan Province and that in quartz from Laowan granite were determined by inductively coupled plasma-mass-spectrometry （ICP-MS） to trace the source of ore-forming materials. Meanwhile, the REE compositions of the deposit ore, granite and metamorphic wall rock were also considered for comparative studies in detail. The range of ∑REE of quartz and pyrite from the deposit ores is 4.18 × 10^-6- 30.91 × 10^-6, the average of ∑REE is 13.39 × 10^-6, and the average of ∑REE of quartz in the Laowan granite is 6.68 × 10^-6. There is no distinct difference of REE parameters between the deposit ore quartz and granite quartz. The quartz in gold deposit has the same REE particular parameters as quartzes from Laowan granite, such as δEu, δCe, （La/Yb）N and （La/Sm）N, partition degree of LREE to HREE, especially, the chondrite-normalized REE patterns, but no similarity to those from metamorphic wall rock, which shows that ore-forming hydrothermal fluid is mainly the fluid coming from the Laowan granite magma, rather than metamorphic fluid. Meanwhile, comparison studies on REE features between minerals from the deposit ores and related geological bodies in the deposit show that REE characteristics of minerals can serve as an indicator of ore-forming fluid properties and sources, while the REE characteristics of the bulk samples （such as deposit ores, granites and wall rocks） can not trace the source of the ore-forming materials exactly.展开更多
The compositions of REE in quartz and pyrite from main mineralized stage of the Laowan gold deposit in Henan province and that of quartz from Laowan granite were determined by Inductively Coupled Plasma-Mass-Spectrome...The compositions of REE in quartz and pyrite from main mineralized stage of the Laowan gold deposit in Henan province and that of quartz from Laowan granite were determined by Inductively Coupled Plasma-Mass-Spectrometry （ICP-MS）. The REE of deposit ore of the Laowan gold deposit, wall-rock and Laowan granite also were studied to trace the source of metallogenic materials in Laowan gold deposit in detail. The range of ∑ REE in quartz and pyrite from gold deposit is 4.18 × 10^-6 - 30.91 × 10^-6, average of 13.39 × 10^-6, 6.68 × 10^-6 of the Laowan granite quartz, obviously lower to REE concentration of deposit, granite and wall-rock. The value of （La/ Yb）N and （La/Sm）N of ore minerals from the gold deposit is 13.23 and 4.17 respectively. The differences in REE parameters, such as δEu, δCe and diffusion degree in REE from light to heavy, among deposit ore minerals and granite mineral are weak. Especially, there are no differences between the chondrite-normalised REE curves of minerals from gold deposit and those of quartzs in Laowan granite, no similarity to wall-rock＇, which shows that ore-forming hydrothermal fluid mainly came from magma fluid resulting from the Laowan granite magma, metamorphic fluid in few. The results also show that REE characteristics of ore minerals in deposit are effective for disclosing oreforming fluid quality comparing with deposit ore＇REE compositions.展开更多
The Laowan deposit is a large gold deposit in the Qinling-Dabie orogenic belt where pyrite is the main Au-bearing mineral phase.We present results from the occurrences of gold,trace elements and sulfur isotopes of pyr...The Laowan deposit is a large gold deposit in the Qinling-Dabie orogenic belt where pyrite is the main Au-bearing mineral phase.We present results from the occurrences of gold,trace elements and sulfur isotopes of pyrite,and hydrogen and oxygen isotopes of quartz and calcite to elucidate the sources of ore-forming fluid;the genesis of pyrite and the ore-forming process.From field observations,five generations of pyrite are identified;one formed in a metamorphic-diagenetic epoch(PyI),and the others during four mineralization stages:1)the coarse-grained pyrite-quartz stage(PyII),2)the quartz and medium-to fine-grained pyrite stage(PyIII),3)the polymetallic sulfide stage(PyIV),and 4)the carbonate-quartz stage(PyV).Gold mainly occurs in PyIII and PyIV.We find that Au,Ag,Pb,and Cu are incorporated into pyrite as micro-/nano-inclusions and that Co,Ni,As,and Se enter the pyrite lattice via isomorphous replacement.The Co/Ni values and Se concentrations indicate that PyI formed from metamorphic hydrothermal fluids and that pyrites(PyII,PyIII,and PyIV)from the ore-forming stages typically reflect a hydrothermal genesis involving magmatic fluid.Theδ^34S values of PyI(1.45‰-2.09‰)are similar to that of plagioclase amphibole schist,indicating that S was primarily derived from wall rock,while those of PyII,PyIII,and PyIV(3.10‰-5.55‰)suggest that S was derived from the Guishanyan Formation and the Laowan granite.The four mineralization stages show a systematic decrease inδD(from−77.1‰to−82.8‰,−84.7‰,and−102.7‰),while theδ^18OH2O values showed a gradual decrease from 5.7 to 2.7‰,1.0‰,and−1.3‰.These data show that the ore-forming fluid was similar to a mixture of magmatic and meteoric waters.Thus,we conclude that the Laowan gold deposit is related to magmatic-hydrothermal fluid.展开更多
文摘The compositions of REE in quartz and pyrite from the main stage of the Laowan gold deposit in Henan Province and that in quartz from Laowan granite were determined by inductively coupled plasma-mass-spectrometry （ICP-MS） to trace the source of ore-forming materials. Meanwhile, the REE compositions of the deposit ore, granite and metamorphic wall rock were also considered for comparative studies in detail. The range of ∑REE of quartz and pyrite from the deposit ores is 4.18 × 10^-6- 30.91 × 10^-6, the average of ∑REE is 13.39 × 10^-6, and the average of ∑REE of quartz in the Laowan granite is 6.68 × 10^-6. There is no distinct difference of REE parameters between the deposit ore quartz and granite quartz. The quartz in gold deposit has the same REE particular parameters as quartzes from Laowan granite, such as δEu, δCe, （La/Yb）N and （La/Sm）N, partition degree of LREE to HREE, especially, the chondrite-normalized REE patterns, but no similarity to those from metamorphic wall rock, which shows that ore-forming hydrothermal fluid is mainly the fluid coming from the Laowan granite magma, rather than metamorphic fluid. Meanwhile, comparison studies on REE features between minerals from the deposit ores and related geological bodies in the deposit show that REE characteristics of minerals can serve as an indicator of ore-forming fluid properties and sources, while the REE characteristics of the bulk samples （such as deposit ores, granites and wall rocks） can not trace the source of the ore-forming materials exactly.
文摘The compositions of REE in quartz and pyrite from main mineralized stage of the Laowan gold deposit in Henan province and that of quartz from Laowan granite were determined by Inductively Coupled Plasma-Mass-Spectrometry （ICP-MS）. The REE of deposit ore of the Laowan gold deposit, wall-rock and Laowan granite also were studied to trace the source of metallogenic materials in Laowan gold deposit in detail. The range of ∑ REE in quartz and pyrite from gold deposit is 4.18 × 10^-6 - 30.91 × 10^-6, average of 13.39 × 10^-6, 6.68 × 10^-6 of the Laowan granite quartz, obviously lower to REE concentration of deposit, granite and wall-rock. The value of （La/ Yb）N and （La/Sm）N of ore minerals from the gold deposit is 13.23 and 4.17 respectively. The differences in REE parameters, such as δEu, δCe and diffusion degree in REE from light to heavy, among deposit ore minerals and granite mineral are weak. Especially, there are no differences between the chondrite-normalised REE curves of minerals from gold deposit and those of quartzs in Laowan granite, no similarity to wall-rock＇, which shows that ore-forming hydrothermal fluid mainly came from magma fluid resulting from the Laowan granite magma, metamorphic fluid in few. The results also show that REE characteristics of ore minerals in deposit are effective for disclosing oreforming fluid quality comparing with deposit ore＇REE compositions.
基金This research was supported by the Project of the Nanyang Basin and Orogenic Belt Metallogenic Diversity Research(No.2014-49)supported by No.1 Geological Exploration Institute,Henan Bureau of Geo-exploration and Mineral Development.
文摘The Laowan deposit is a large gold deposit in the Qinling-Dabie orogenic belt where pyrite is the main Au-bearing mineral phase.We present results from the occurrences of gold,trace elements and sulfur isotopes of pyrite,and hydrogen and oxygen isotopes of quartz and calcite to elucidate the sources of ore-forming fluid;the genesis of pyrite and the ore-forming process.From field observations,five generations of pyrite are identified;one formed in a metamorphic-diagenetic epoch(PyI),and the others during four mineralization stages:1)the coarse-grained pyrite-quartz stage(PyII),2)the quartz and medium-to fine-grained pyrite stage(PyIII),3)the polymetallic sulfide stage(PyIV),and 4)the carbonate-quartz stage(PyV).Gold mainly occurs in PyIII and PyIV.We find that Au,Ag,Pb,and Cu are incorporated into pyrite as micro-/nano-inclusions and that Co,Ni,As,and Se enter the pyrite lattice via isomorphous replacement.The Co/Ni values and Se concentrations indicate that PyI formed from metamorphic hydrothermal fluids and that pyrites(PyII,PyIII,and PyIV)from the ore-forming stages typically reflect a hydrothermal genesis involving magmatic fluid.Theδ^34S values of PyI(1.45‰-2.09‰)are similar to that of plagioclase amphibole schist,indicating that S was primarily derived from wall rock,while those of PyII,PyIII,and PyIV(3.10‰-5.55‰)suggest that S was derived from the Guishanyan Formation and the Laowan granite.The four mineralization stages show a systematic decrease inδD(from−77.1‰to−82.8‰,−84.7‰,and−102.7‰),while theδ^18OH2O values showed a gradual decrease from 5.7 to 2.7‰,1.0‰,and−1.3‰.These data show that the ore-forming fluid was similar to a mixture of magmatic and meteoric waters.Thus,we conclude that the Laowan gold deposit is related to magmatic-hydrothermal fluid.
