As we know there is a famous East Qinling-Dabie molybdenum belt in china,where many molybdenum deposits located such as super giant Jinduicheng,Sandaozhuang,Shangfanggou and Nannihu molybdenum deposits(Li,2008) ;The m...As we know there is a famous East Qinling-Dabie molybdenum belt in china,where many molybdenum deposits located such as super giant Jinduicheng,Sandaozhuang,Shangfanggou and Nannihu molybdenum deposits(Li,2008) ;The molybdenum mineralization in the East Qinling-Dabie belt clusters into three groups or mineralization pulses:233-221,148-138 and 131-112 Ma(Mao et al,2008).展开更多
After the survey and analysis of economic development, infrastructure, eco-environment and social development of Wenquan Town, by adopting Analytical Hierarchy Process and selecting 31 ecological evaluation factors, e...After the survey and analysis of economic development, infrastructure, eco-environment and social development of Wenquan Town, by adopting Analytical Hierarchy Process and selecting 31 ecological evaluation factors, evaluation models of circular economic system, infrastructure system, eco-environment system and social development system have been established and the judgment matrix has been constructed. Then, the ecological construction situation of Wenquan Tourist Town has been evaluated comprehensively. Evaluation results show that important indexes affecting eco-environment construction situation of Wenquan Tourist Town contain average value of urban air pollution index, drinking water source qualification rate and average value of urban environmental noise; while indexes making less influence include social political management, environmental protection investment index and natural growth rate of population.展开更多
A near NS-strike east-dipping normal fault is developed on the western side of Wenquan graben in the central Qinghal-Xizang（Tibet） Plateau. It is the western marginal fault of the graben and has been intensely activ...A near NS-strike east-dipping normal fault is developed on the western side of Wenquan graben in the central Qinghal-Xizang（Tibet） Plateau. It is the western marginal fault of the graben and has been intensely active. It is a product of the near EW extension and deformation of the central northern Qinghal-Xizang（Tibet） Plateau since the late Cenozoic under the effect of the collision of the India and Eurasia plates. Since the late Cenozoic, the maximum vertical displacement on the fault was greater than 2. ! km, and the dislocated Mesozoic fold stratum reveals a maximum accumulative throw of 6.0 ± 2.2km. Quaternary faulting took place many times along the fault, creating multi-set piedmont fault facets and multi-level fault scarplets.According to the height of fault scarps that result from the vertical offset of the late Quaternary strata and geomorphic provinces, the maximum slip rate of the fault is estimated to have been less than 1.2mm/a since the late Quaternary, averaging 0.45mm/a. The trenching across the fault reveals that at least 3 paleoearthquakes of varied magnitudes have occurred since the late Epipleistocene. In view of the characteristics of Cenozoic faulting, it is concluded that the fault will act as a dominant seismogenic fault for earthquakes of M6.0 to M7.0 that are most likely to occur in the future.展开更多
The Wenquan molybdenum deposit is a kind of large-sized porphyry molybdenum deposit found in re-cent years.In this paper,on the basis of deposit geology,geochemistry and isotope geochronology data,the metal-logenic mo...The Wenquan molybdenum deposit is a kind of large-sized porphyry molybdenum deposit found in re-cent years.In this paper,on the basis of deposit geology,geochemistry and isotope geochronology data,the metal-logenic model of this deposit was established.The Wenquan granitic batholith belongs to the K-rich(alkali-rich) calc-alkaline rock series,which is the mineralization parent rock.The rock massif shows the characteristics of both crust-remelting granite and mantle-source granite.At the same time,the data of REE contents,hydrogen and oxygen isotopes and inclusion temperatures showed that the metallogenic hydrothermal solution is a mixed mesothermal solution of magmato-hydrothermal fluid and meteoric water.Mineralization was dated at 214±7.1 Ma,basically identical with the parent rock's age(207-226 Ma).This reflects that molybdenum mineralization has a close relation to tectonic magmatism evoked by orogenic processes,and molybdenum mineralization occurred mainly at the petrogenesis stage at the late stage of magma emplacement.Mixing with meteoric water led to a decrease in the sa-linity of magmato-hydrothermal solution and changes in other physical and chemical properties.During the tectonic process,ore-bearing hydrothermal solution ascended along favorable fault structure channels.With physicochemical changes,it filled in the surrounding rock joints on both sides of faults,forming ore deposits.展开更多
The Wenquan molybdenum deposit is associated with a Triassic granite in this area.The Wenquan granite is enriched in LILE and LREE,poor in HFSE,and has significantly higher contents of alkali(K2O+Na2O) and Sr,Ba than ...The Wenquan molybdenum deposit is associated with a Triassic granite in this area.The Wenquan granite is enriched in LILE and LREE,poor in HFSE,and has significantly higher contents of alkali(K2O+Na2O) and Sr,Ba than those of the island arc volcanic rocks.These geochemical characteristics are similar to post-collisional granites in high K calc-alkaline series.Studies of major elements,trace elements,REEs and chronology of the Wenquan pluton show that,in the geodynamic transition stage of continent-continent convergence to extension,the partial melting of the enriched lithospheric mantle generated the basaltic magma and triggered the partial melting of the thickened lower crust which produceded the acidic magma,and the Wenquan pluton was formed by mixing of the two magmas.Molybdenite Re-Os isotopic dating gave Os model ages of 212.7±2.6 Ma to 215.1±2.6 Ma with a weighted mean of 214.1±1.1 Ma,and an Re-Os isochron age of 214.4±7.1 Ma.These ages are close to K-Ar ages(223 to 226 Ma) and a SHRIMP zircon U-Pb age(223±7 Ma) for the Wenquan granite within the error range,but relatively younger.This implies that the Mo mineralization occurred in a late stage of the magmatic intrusion,and the metallogenesis took place in the transition stage from syn-collision to post-collision in the tectonic setting of the Qinling Orogenic Belt(QOB) after continental collision be-tween the North China Block(NCB) and the South China Block(SCB).This process is also corre-sponding to the geological events of metamorphism and deformation in South Qinling,closure of the Mian-Lue oceanic basin,and exhumation of the Dabie-Sulu ultrahigh-pressure metamorphic rocks.The large-scale continent-continent collision between NCB and SCB in the middle Triassic triggered sig-nificant crustal thickening and exhumation of subducted slab.In the late Triassic,the tectonic setting was transformed to the transition stage from collision to extension.Materials from the asthenospheric mantle would ascend into the root of the lower crust,which could induce partial melting of the lower crust and generate Mo-enriched granitic magma.The ore-forming elements enriched in the fluid derived from the condensation and fraction of the magma resulted in the Mo mineralization.The Mo deposits in the QOB are mainly formed in two episodes,namely 220± Ma and 140± Ma.The two episodes of metal-logenesis were developed in the tectonic transition settings from compression to extension,but they were in the different stages of the tectonic evolution.The occurrence of the Wenquan Mo-bearing plu-ton indicates that the Triassic tectonic-magmatic belt of Western Qinling is another favorable region for Mo mineralization in the QOB.Therefore,it is significant to pay more attention to evaluation of the ore-forming potentiality in the Triassic granites in Western Qinling.展开更多
文摘As we know there is a famous East Qinling-Dabie molybdenum belt in china,where many molybdenum deposits located such as super giant Jinduicheng,Sandaozhuang,Shangfanggou and Nannihu molybdenum deposits(Li,2008) ;The molybdenum mineralization in the East Qinling-Dabie belt clusters into three groups or mineralization pulses:233-221,148-138 and 131-112 Ma(Mao et al,2008).
文摘After the survey and analysis of economic development, infrastructure, eco-environment and social development of Wenquan Town, by adopting Analytical Hierarchy Process and selecting 31 ecological evaluation factors, evaluation models of circular economic system, infrastructure system, eco-environment system and social development system have been established and the judgment matrix has been constructed. Then, the ecological construction situation of Wenquan Tourist Town has been evaluated comprehensively. Evaluation results show that important indexes affecting eco-environment construction situation of Wenquan Tourist Town contain average value of urban air pollution index, drinking water source qualification rate and average value of urban environmental noise; while indexes making less influence include social political management, environmental protection investment index and natural growth rate of population.
文摘A near NS-strike east-dipping normal fault is developed on the western side of Wenquan graben in the central Qinghal-Xizang（Tibet） Plateau. It is the western marginal fault of the graben and has been intensely active. It is a product of the near EW extension and deformation of the central northern Qinghal-Xizang（Tibet） Plateau since the late Cenozoic under the effect of the collision of the India and Eurasia plates. Since the late Cenozoic, the maximum vertical displacement on the fault was greater than 2. ! km, and the dislocated Mesozoic fold stratum reveals a maximum accumulative throw of 6.0 ± 2.2km. Quaternary faulting took place many times along the fault, creating multi-set piedmont fault facets and multi-level fault scarplets.According to the height of fault scarps that result from the vertical offset of the late Quaternary strata and geomorphic provinces, the maximum slip rate of the fault is estimated to have been less than 1.2mm/a since the late Quaternary, averaging 0.45mm/a. The trenching across the fault reveals that at least 3 paleoearthquakes of varied magnitudes have occurred since the late Epipleistocene. In view of the characteristics of Cenozoic faulting, it is concluded that the fault will act as a dominant seismogenic fault for earthquakes of M6.0 to M7.0 that are most likely to occur in the future.
文摘The Wenquan molybdenum deposit is a kind of large-sized porphyry molybdenum deposit found in re-cent years.In this paper,on the basis of deposit geology,geochemistry and isotope geochronology data,the metal-logenic model of this deposit was established.The Wenquan granitic batholith belongs to the K-rich(alkali-rich) calc-alkaline rock series,which is the mineralization parent rock.The rock massif shows the characteristics of both crust-remelting granite and mantle-source granite.At the same time,the data of REE contents,hydrogen and oxygen isotopes and inclusion temperatures showed that the metallogenic hydrothermal solution is a mixed mesothermal solution of magmato-hydrothermal fluid and meteoric water.Mineralization was dated at 214±7.1 Ma,basically identical with the parent rock's age(207-226 Ma).This reflects that molybdenum mineralization has a close relation to tectonic magmatism evoked by orogenic processes,and molybdenum mineralization occurred mainly at the petrogenesis stage at the late stage of magma emplacement.Mixing with meteoric water led to a decrease in the sa-linity of magmato-hydrothermal solution and changes in other physical and chemical properties.During the tectonic process,ore-bearing hydrothermal solution ascended along favorable fault structure channels.With physicochemical changes,it filled in the surrounding rock joints on both sides of faults,forming ore deposits.
基金Supported by the National Basic Research Program of China(Grant No.2006CB403502)National General Investigation Program of China(Grant No.1212010631007)+3 种基金National Natural Science Foundation of China(Grant No.40872071)Foundation of State Key Laboratory of Ore Deposit Geochemistry,Chinese Academy of Sciences(Grant No.20060)Foundation of Educational Bureau of Shaanxi Province Foundation(Grant No.07JK414)Foundation of State Key Laboratory for Mineral Deposits Research,Nanjing University(Grant No.14-08-1)
文摘The Wenquan molybdenum deposit is associated with a Triassic granite in this area.The Wenquan granite is enriched in LILE and LREE,poor in HFSE,and has significantly higher contents of alkali(K2O+Na2O) and Sr,Ba than those of the island arc volcanic rocks.These geochemical characteristics are similar to post-collisional granites in high K calc-alkaline series.Studies of major elements,trace elements,REEs and chronology of the Wenquan pluton show that,in the geodynamic transition stage of continent-continent convergence to extension,the partial melting of the enriched lithospheric mantle generated the basaltic magma and triggered the partial melting of the thickened lower crust which produceded the acidic magma,and the Wenquan pluton was formed by mixing of the two magmas.Molybdenite Re-Os isotopic dating gave Os model ages of 212.7±2.6 Ma to 215.1±2.6 Ma with a weighted mean of 214.1±1.1 Ma,and an Re-Os isochron age of 214.4±7.1 Ma.These ages are close to K-Ar ages(223 to 226 Ma) and a SHRIMP zircon U-Pb age(223±7 Ma) for the Wenquan granite within the error range,but relatively younger.This implies that the Mo mineralization occurred in a late stage of the magmatic intrusion,and the metallogenesis took place in the transition stage from syn-collision to post-collision in the tectonic setting of the Qinling Orogenic Belt(QOB) after continental collision be-tween the North China Block(NCB) and the South China Block(SCB).This process is also corre-sponding to the geological events of metamorphism and deformation in South Qinling,closure of the Mian-Lue oceanic basin,and exhumation of the Dabie-Sulu ultrahigh-pressure metamorphic rocks.The large-scale continent-continent collision between NCB and SCB in the middle Triassic triggered sig-nificant crustal thickening and exhumation of subducted slab.In the late Triassic,the tectonic setting was transformed to the transition stage from collision to extension.Materials from the asthenospheric mantle would ascend into the root of the lower crust,which could induce partial melting of the lower crust and generate Mo-enriched granitic magma.The ore-forming elements enriched in the fluid derived from the condensation and fraction of the magma resulted in the Mo mineralization.The Mo deposits in the QOB are mainly formed in two episodes,namely 220± Ma and 140± Ma.The two episodes of metal-logenesis were developed in the tectonic transition settings from compression to extension,but they were in the different stages of the tectonic evolution.The occurrence of the Wenquan Mo-bearing plu-ton indicates that the Triassic tectonic-magmatic belt of Western Qinling is another favorable region for Mo mineralization in the QOB.Therefore,it is significant to pay more attention to evaluation of the ore-forming potentiality in the Triassic granites in Western Qinling.
