Orogenically-derived gold deposits of the Zhongchuan area in the western Qinling are distributed in the exo-contact thermal metamorphic zone. The country rocks hosting the deposits are predominantly of Devonian age wi...Orogenically-derived gold deposits of the Zhongchuan area in the western Qinling are distributed in the exo-contact thermal metamorphic zone. The country rocks hosting the deposits are predominantly of Devonian age with low-grade metamorphism and strong deformation with the ore deposits directly controlled by multi-level tectonic systems. Three types of inclusions from these deposits have been recognized: CO2-H2O, CO2-rich, and aqueous. The ore-forming fluids were mainly CO2-NaCl-H2O type characterized by rich CO2, low salinity, high temperature and immiscibility. Incorporated with earlier isotopic data, the regional geological setting and features of diagenesis and metallogeny, it can be concluded that the ore-forming fluids were derived from deep magma and mixed with meteoric and metamorphic water. The deposits formed during an intra-continent collisional orogeny, and some of the materials derived from the deep might have been involved in the ore-forming process.展开更多
[ Objective] The aim was to study the biodiversity and its protection measures in Qinling. [Method] The current situation and protection measures of the biodiversity in Qinling area were reviewed by the perspective of...[ Objective] The aim was to study the biodiversity and its protection measures in Qinling. [Method] The current situation and protection measures of the biodiversity in Qinling area were reviewed by the perspective of eco-safety and the eco-value. [Result] Qinling is the natural gene bank for the study of the origin and development of living beings. Forest ecological system is the main body, with many ecological systems and com- plete vertical spectrometer. The plants have various varieties, complicated components, rare species, rich special plant and old heritance. There were 722 species of vertebrates, including 162 species in 16 families of 7 orders of fish, 26 species in 8 families of 2 orders of amphibian, 44 species in 8 families of 2 orders of reptiles, 373 species in 53 families of 17 orders of birds, and 117 species in 27 families of 7 orders of animals. The num- ber of order, family and species of vertebrates was 70%, 53.04% and 22.06%. It was suggested to formulate policy promoting biodiversity protec- tion and sustainable development, building natural protection net system to protect biodiversity in Qinling. [ Coecluslon] The study provided theoreti- cal basis for the protection of biodiversity in Qinling area.展开更多
A W-Mo mineralized region is located along the northern margin of the South Qinling tectonic belt of China. WMo mineralization occurs mainly in Cambrian–Ordovician clastic and carbonate rocks, and the ore bodies are ...A W-Mo mineralized region is located along the northern margin of the South Qinling tectonic belt of China. WMo mineralization occurs mainly in Cambrian–Ordovician clastic and carbonate rocks, and the ore bodies are structurally controlled by NW–SE-and NNE–SSW-striking faults. Evidence for magmatism in the area is widespread and is dominated by intermediate–felsic intrusives or apophyses, such as the Dongjiangkou, Yanzhiba, Lanbandeng, and Sihaiping granitic bodies. Quartz-vein-type mineralization and fault-controlled skarn-type mineralization dominate the ore systems, with additional enrichment in residual deposits. At present, there are few or insufficient studies on(1) the age of mineralization,(2) the relationship between intermediate–felsic granite and W-Mo mineralization,(3) the source of ore-forming materials, and(4) the metallogenic and tectonic setting of the mineralized area. In this paper, we present geochronology results for numerous intrusive granitic bodies in the South Qinling tectonic belt. U-Pb zircon geochronology of the Lanbandeng monzogranite and Wangjiaping biotite monzogranite yields ages of 222.7 ± 2.3 and 201.9 ± 1.8 Ma, respectively. In contrast to the Late Triassic age of the Lanbandeng monzogranite, the age of the newly discovered Wangjiaping biotite monzogranite places it at the Triassic–Jurassic boundary. Re-Os molybdenite geochronology on the Qipangou W-Mo deposit yielded a model age of 199.7 ± 3.9 Ma, indicating the deposit formed in the early Yanshanian period of the Early Jurassic. Granitoid intrusions in the mineralized area are characterized by composite granite bodies that crystallized at ca. 240–190 Ma. While there were multiple stages of intrusion, most occurred at 210–220 Ma, with waning magmatic activity at 200–190 Ma. The Re-Os age of molybdenite in the region is ca. 200–190 Ma, which may represent a newly discovered period of W-Mo metallogenesis that occurred during the final stages of magmatism. The heat associated with this magmatism drove ore formation and might have provided additional ore-forming components for metallogenesis(represented by the Wangjiaping biotite monzogranite). Ore materials in the mineralized area were derived from mixed crustal and mantle sources. Enrichment of the region occurred during intracontinental orogenesis in the late Indosinian–Yanshanian, subsequent to the main Indosinian collision. At this time, the tectonic environment was dominated by extension and strike-slip motion.展开更多
The Huanggang intrusive complex in northern Tongbai area was formed in Early Paleozoic. It mainly consists of ultra basic, basic, intermediate and acid rocks, dominated by intermediate and basic rocks. The complex be...The Huanggang intrusive complex in northern Tongbai area was formed in Early Paleozoic. It mainly consists of ultra basic, basic, intermediate and acid rocks, dominated by intermediate and basic rocks. The complex belongs to calc alkaline series. Geochemical characteristics of major and trace elements show that the complex was derived from the fractional crystallization of co source magma. It is suggested that the complex was formed in island arc tectonic environment and was closely related to the northward subduction of the Erlangping back arc basin. Thus, the subduction of the back arc basin can induce the island arc type magmatism similar to the one formed in the setting of ocean plate subduction.展开更多
The vegetation restoration experiment was carried out by selecting the arbor-shrub-grass plants with strong stress resistances in the drawdown area of the reservoir of Chongqing Bashan Lake National Wetland Park.The r...The vegetation restoration experiment was carried out by selecting the arbor-shrub-grass plants with strong stress resistances in the drawdown area of the reservoir of Chongqing Bashan Lake National Wetland Park.The results showed that the survival rate of Taxodium distichum was only 33% in August since the completion of the planting in May 2017,while the survival rates of other plant species were all 100%.After the rising and falling of water levels from September 2017 to February 2018,the investigations conducted in April 2018 showed that the flooding lasted for 130 d at the altitude of 668-672 m,where the preserving rate of Betula nigra was very low of only 25%.The flooding lasted for 120 d at the altitude of 672-675 m,where B.nigra,Pontederia cordata,and Thalia dealbata showed good preserving conditions with the preserving rates over 55%,while Canna indica,Cyperus alternifolius and Iris tectorum had poor preserving conditions with the rates below 50%.The drawdown area with the altitude of 675-678 m had the flooding lasted for 84 d,and good preserving conditions were found in B.nigra,T.distichum,Pterocarya stenoptera,Distylium chinense,Rosa multiflora,P.cordata,T.dealbata and Iris tectorum,which had the preserving rates reach up to 65%,and the preserving rate of B.nigra was as high as 76.2%,but the preserving rates of C.indica and C.alternifolius were low.展开更多
Ancient MORB-type rocks (AMORB) from the Qinling Orogenic Belt show a high radiogenic Ph isotope and their initial Pb isotopic ratios are close to the growth curve for μ =8.5. The Pb isotopic features of Qinling AMOR...Ancient MORB-type rocks (AMORB) from the Qinling Orogenic Belt show a high radiogenic Ph isotope and their initial Pb isotopic ratios are close to the growth curve for μ =8.5. The Pb isotopic features of Qinling AMORBs suggest that mantle source was similar to the mantle of Tethyan and of Gondwana domain from the South Hemisphere. This indicates the presence of a Qinling paleo-ocean which has been consumed and has separated North China and Yangtze cratons. The Qinling ocean was possibly part of the ocean including Gondwana domain and Paleo-or Proto Tethys. DUPAL anomaly is a large-scale Pb and Sr isotopic anomaly in oceanic basalts from the South Hemisphere[1]. The paleo-DUPAL anomaly, which has been recognized in Qinling AMORBs, is proven to exist 1.0Ga ago. The results infer that the DUPAL component of the Qinling AMORB is related to the DUPAL anomaly of the South Hemisphere in the geological history.展开更多
Baihua meta-igneous complex consists mainly of pyroxenite-gabbro(diorite)-diorite-quartz diorite. They form a complete comagmatic evolutionary series. The geochemical characteristics of basic-interme- diate basic igne...Baihua meta-igneous complex consists mainly of pyroxenite-gabbro(diorite)-diorite-quartz diorite. They form a complete comagmatic evolutionary series. The geochemical characteristics of basic-interme- diate basic igneous rocks indicate that they belong to a tholeiite suite. The REE distribution pattern is nearly flat type and LREE is slightly enriched type, and their primitive mantle-normalized and MORB-normalized trace element spider diagrams are generally similar; the LIL elements (LILE) Cs, Ba, Sr, Th and U are enriched, but Rb, K and the HFSEs Nb, P, Zr, Sm, Ti and Y are relatively depleted. All these show comagmatic evolution and origin characteristics. The tectonics environment discrimination of trace element reveals that these igneous complexes formed in an island-arc setting. The LA-ICP-MS single-zircons U-Pb age of Baihua basic igneous complex is 434.6±1.5 Ma (MSWD = 1.3), which proves that the formation time of the island-arc type magmatite in the northern zone of West Qinling is Late Ordovician or Early Silurian, also reveals that the timing of subduction of paleo-ocean basin represented by the Guanzizhen ophiolite and resulting island-arc-type magmatic activities is probably Middle-Late Ordovician to Early Silurian.展开更多
The Qinling Orogen is a composite orogenic belt that can be subdivided into the North and South Qinling,broadly separated by the Shangdan suture zone.These two orogenic belts were generated by subduction-collisional p...The Qinling Orogen is a composite orogenic belt that can be subdivided into the North and South Qinling,broadly separated by the Shangdan suture zone.These two orogenic belts were generated by subduction-collisional processes in the Early Paleozoic and Late Triassic,respectively.During the Late Jurassic to Early Cretaceous,the eastern portion of the Qinling Orogen was tectonically reactivated due to westerly subduction of the Izanagi plate underneath the East China continental margin.The Qinling Orogen is well-endowed with numerous Au,Mo,Ag-Pb-Zn deposits that predominantly formed in the Late Triassic to Early Cretaceous,with rare Paleozoic varieties documented.In this study,we present garnet and zircon U-Pb dating results to show that the Huoshenmiao iron skarn deposit in the Tongbai area of North Qinling orogenic belt formed in the Early Silurian and is genetically related to subduction-related magmatism.The Huoshenmiao deposit consists of lenticular and stratiform orebodies that contain massive or densely disseminated magnetite variably associated with garnet,diopside,epidote,hornblende,and actinolite.Garnets from iron ores are andradite and grossular in composition(Ad_(83.1)Gr_(13.3)-Ad_(86.5)Gr_(10.2))and characterized by enrichment in light rare earth elements(ΣLREE=57.85-103.82 ppm)and depletion in heavy rare earth elements(ΣHREE=5.50-11.34 ppm),with significantly positive Eu and Ce anomalies(δEu of 1.09-1.89 andδCe of 1.39-1.69).These compositional signatures are distinctly different from those of garnets in the ore-hosting metamorphic rocks that are typically dominated by almandine,spessartine and grossular(Al_(47.4)Sp_(30.4)Gr_(13.8)-Al_(51.9)Sp_(24.8)Gr_(17.6)),depleted in LREE(0.14-0.69 ppm),enriched in HREE(95.68-841.60 ppm)and have pronounced negative Eu anomalies(δEu=0.24-0.51).In addition,garnets from iron ores of the Huoshenmiao deposit contain abundant daughter mineral-bearing,multiphase fluid inclusions,further confirming their hydrothermal origin.Two samples of those hydrothermal garnets yield U-Pb dates of 437±9 Ma and 437±10 Ma(2σ),revealing a Paleozoic mineralization event that has long been ignored and rarely documented.These garnet dates agree well with zircon U-Pb dates of 438±4 Ma to 436±3 Ma for a gabbroic diorite and 430±4 Ma for a granite intrusion in close proximity of the mine,supporting a possible genetic link between the iron mineralization and Early Silurian magmatism.The Paleozoic intrusions are enriched in large ion lithophile elements(LILEs:Ba,K,Sr)and LREEs,depleted in high field strength elements(HFSEs:Nb,Ta,P,Ti),have whole-rock(^(87)Sr/^(86)Sr)i,ε_(Nd)(t),and zirconεHf(t)values of 0.7039-0.7042,3.32-4.33,and 13.0-14.9,respectively.These geochemical and isotopic characteristics suggest that the Paleozoic intrusions were affiliated with arc magmatism triggered by subduction of the Shangdan oceanic plate in the Early Paleozoic.Recognition of the Silurian Huoshenmiao iron skarn deposit opens a new window for exploration of Paleozoic mineral resources in the Tongbai area and other portions of the North Qinling Orogen.展开更多
文摘Orogenically-derived gold deposits of the Zhongchuan area in the western Qinling are distributed in the exo-contact thermal metamorphic zone. The country rocks hosting the deposits are predominantly of Devonian age with low-grade metamorphism and strong deformation with the ore deposits directly controlled by multi-level tectonic systems. Three types of inclusions from these deposits have been recognized: CO2-H2O, CO2-rich, and aqueous. The ore-forming fluids were mainly CO2-NaCl-H2O type characterized by rich CO2, low salinity, high temperature and immiscibility. Incorporated with earlier isotopic data, the regional geological setting and features of diagenesis and metallogeny, it can be concluded that the ore-forming fluids were derived from deep magma and mixed with meteoric and metamorphic water. The deposits formed during an intra-continent collisional orogeny, and some of the materials derived from the deep might have been involved in the ore-forming process.
基金Supported by Opening Fund of State Key Laboratory of Loess and Quaternary Geology
文摘[ Objective] The aim was to study the biodiversity and its protection measures in Qinling. [Method] The current situation and protection measures of the biodiversity in Qinling area were reviewed by the perspective of eco-safety and the eco-value. [Result] Qinling is the natural gene bank for the study of the origin and development of living beings. Forest ecological system is the main body, with many ecological systems and com- plete vertical spectrometer. The plants have various varieties, complicated components, rare species, rich special plant and old heritance. There were 722 species of vertebrates, including 162 species in 16 families of 7 orders of fish, 26 species in 8 families of 2 orders of amphibian, 44 species in 8 families of 2 orders of reptiles, 373 species in 53 families of 17 orders of birds, and 117 species in 27 families of 7 orders of animals. The num- ber of order, family and species of vertebrates was 70%, 53.04% and 22.06%. It was suggested to formulate policy promoting biodiversity protec- tion and sustainable development, building natural protection net system to protect biodiversity in Qinling. [ Coecluslon] The study provided theoreti- cal basis for the protection of biodiversity in Qinling area.
基金Shaanxi Mineral Resources and Geological Survey (Grant no. 214027160195)a project on magmatism and W-Mo mineralization in the mineralized areas of western Zhen’anShaanxi Mineral Resources and Geological Survey (Grant no. 61201506280)a project that combined exploration and technical approaches in the mineralized areas of the Qinling mineralized belt。
文摘A W-Mo mineralized region is located along the northern margin of the South Qinling tectonic belt of China. WMo mineralization occurs mainly in Cambrian–Ordovician clastic and carbonate rocks, and the ore bodies are structurally controlled by NW–SE-and NNE–SSW-striking faults. Evidence for magmatism in the area is widespread and is dominated by intermediate–felsic intrusives or apophyses, such as the Dongjiangkou, Yanzhiba, Lanbandeng, and Sihaiping granitic bodies. Quartz-vein-type mineralization and fault-controlled skarn-type mineralization dominate the ore systems, with additional enrichment in residual deposits. At present, there are few or insufficient studies on(1) the age of mineralization,(2) the relationship between intermediate–felsic granite and W-Mo mineralization,(3) the source of ore-forming materials, and(4) the metallogenic and tectonic setting of the mineralized area. In this paper, we present geochronology results for numerous intrusive granitic bodies in the South Qinling tectonic belt. U-Pb zircon geochronology of the Lanbandeng monzogranite and Wangjiaping biotite monzogranite yields ages of 222.7 ± 2.3 and 201.9 ± 1.8 Ma, respectively. In contrast to the Late Triassic age of the Lanbandeng monzogranite, the age of the newly discovered Wangjiaping biotite monzogranite places it at the Triassic–Jurassic boundary. Re-Os molybdenite geochronology on the Qipangou W-Mo deposit yielded a model age of 199.7 ± 3.9 Ma, indicating the deposit formed in the early Yanshanian period of the Early Jurassic. Granitoid intrusions in the mineralized area are characterized by composite granite bodies that crystallized at ca. 240–190 Ma. While there were multiple stages of intrusion, most occurred at 210–220 Ma, with waning magmatic activity at 200–190 Ma. The Re-Os age of molybdenite in the region is ca. 200–190 Ma, which may represent a newly discovered period of W-Mo metallogenesis that occurred during the final stages of magmatism. The heat associated with this magmatism drove ore formation and might have provided additional ore-forming components for metallogenesis(represented by the Wangjiaping biotite monzogranite). Ore materials in the mineralized area were derived from mixed crustal and mantle sources. Enrichment of the region occurred during intracontinental orogenesis in the late Indosinian–Yanshanian, subsequent to the main Indosinian collision. At this time, the tectonic environment was dominated by extension and strike-slip motion.
文摘The Huanggang intrusive complex in northern Tongbai area was formed in Early Paleozoic. It mainly consists of ultra basic, basic, intermediate and acid rocks, dominated by intermediate and basic rocks. The complex belongs to calc alkaline series. Geochemical characteristics of major and trace elements show that the complex was derived from the fractional crystallization of co source magma. It is suggested that the complex was formed in island arc tectonic environment and was closely related to the northward subduction of the Erlangping back arc basin. Thus, the subduction of the back arc basin can induce the island arc type magmatism similar to the one formed in the setting of ocean plate subduction.
基金Supported by the Science and Technology Planning Project of Bashan Lake National Wetland Park Management Center of Chengkou County,China
文摘The vegetation restoration experiment was carried out by selecting the arbor-shrub-grass plants with strong stress resistances in the drawdown area of the reservoir of Chongqing Bashan Lake National Wetland Park.The results showed that the survival rate of Taxodium distichum was only 33% in August since the completion of the planting in May 2017,while the survival rates of other plant species were all 100%.After the rising and falling of water levels from September 2017 to February 2018,the investigations conducted in April 2018 showed that the flooding lasted for 130 d at the altitude of 668-672 m,where the preserving rate of Betula nigra was very low of only 25%.The flooding lasted for 120 d at the altitude of 672-675 m,where B.nigra,Pontederia cordata,and Thalia dealbata showed good preserving conditions with the preserving rates over 55%,while Canna indica,Cyperus alternifolius and Iris tectorum had poor preserving conditions with the rates below 50%.The drawdown area with the altitude of 675-678 m had the flooding lasted for 84 d,and good preserving conditions were found in B.nigra,T.distichum,Pterocarya stenoptera,Distylium chinense,Rosa multiflora,P.cordata,T.dealbata and Iris tectorum,which had the preserving rates reach up to 65%,and the preserving rate of B.nigra was as high as 76.2%,but the preserving rates of C.indica and C.alternifolius were low.
基金Project supported by the National Natural Science Foundation of China and the Open Laboratory of Constitution,Interaction and Dynamics of Crust-Mantle System Ministry of Geology and Mineral Resources.
文摘Ancient MORB-type rocks (AMORB) from the Qinling Orogenic Belt show a high radiogenic Ph isotope and their initial Pb isotopic ratios are close to the growth curve for μ =8.5. The Pb isotopic features of Qinling AMORBs suggest that mantle source was similar to the mantle of Tethyan and of Gondwana domain from the South Hemisphere. This indicates the presence of a Qinling paleo-ocean which has been consumed and has separated North China and Yangtze cratons. The Qinling ocean was possibly part of the ocean including Gondwana domain and Paleo-or Proto Tethys. DUPAL anomaly is a large-scale Pb and Sr isotopic anomaly in oceanic basalts from the South Hemisphere[1]. The paleo-DUPAL anomaly, which has been recognized in Qinling AMORBs, is proven to exist 1.0Ga ago. The results infer that the DUPAL component of the Qinling AMORB is related to the DUPAL anomaly of the South Hemisphere in the geological history.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 40234041 and 40572121), the Ministry of Education of China (Grant No. 104175) and China Geological Survey (Grant No. 200013000154)
文摘Baihua meta-igneous complex consists mainly of pyroxenite-gabbro(diorite)-diorite-quartz diorite. They form a complete comagmatic evolutionary series. The geochemical characteristics of basic-interme- diate basic igneous rocks indicate that they belong to a tholeiite suite. The REE distribution pattern is nearly flat type and LREE is slightly enriched type, and their primitive mantle-normalized and MORB-normalized trace element spider diagrams are generally similar; the LIL elements (LILE) Cs, Ba, Sr, Th and U are enriched, but Rb, K and the HFSEs Nb, P, Zr, Sm, Ti and Y are relatively depleted. All these show comagmatic evolution and origin characteristics. The tectonics environment discrimination of trace element reveals that these igneous complexes formed in an island-arc setting. The LA-ICP-MS single-zircons U-Pb age of Baihua basic igneous complex is 434.6±1.5 Ma (MSWD = 1.3), which proves that the formation time of the island-arc type magmatite in the northern zone of West Qinling is Late Ordovician or Early Silurian, also reveals that the timing of subduction of paleo-ocean basin represented by the Guanzizhen ophiolite and resulting island-arc-type magmatic activities is probably Middle-Late Ordovician to Early Silurian.
基金This work was supported by the National Natural Science Foundation of China(Grant No.41772081).
文摘The Qinling Orogen is a composite orogenic belt that can be subdivided into the North and South Qinling,broadly separated by the Shangdan suture zone.These two orogenic belts were generated by subduction-collisional processes in the Early Paleozoic and Late Triassic,respectively.During the Late Jurassic to Early Cretaceous,the eastern portion of the Qinling Orogen was tectonically reactivated due to westerly subduction of the Izanagi plate underneath the East China continental margin.The Qinling Orogen is well-endowed with numerous Au,Mo,Ag-Pb-Zn deposits that predominantly formed in the Late Triassic to Early Cretaceous,with rare Paleozoic varieties documented.In this study,we present garnet and zircon U-Pb dating results to show that the Huoshenmiao iron skarn deposit in the Tongbai area of North Qinling orogenic belt formed in the Early Silurian and is genetically related to subduction-related magmatism.The Huoshenmiao deposit consists of lenticular and stratiform orebodies that contain massive or densely disseminated magnetite variably associated with garnet,diopside,epidote,hornblende,and actinolite.Garnets from iron ores are andradite and grossular in composition(Ad_(83.1)Gr_(13.3)-Ad_(86.5)Gr_(10.2))and characterized by enrichment in light rare earth elements(ΣLREE=57.85-103.82 ppm)and depletion in heavy rare earth elements(ΣHREE=5.50-11.34 ppm),with significantly positive Eu and Ce anomalies(δEu of 1.09-1.89 andδCe of 1.39-1.69).These compositional signatures are distinctly different from those of garnets in the ore-hosting metamorphic rocks that are typically dominated by almandine,spessartine and grossular(Al_(47.4)Sp_(30.4)Gr_(13.8)-Al_(51.9)Sp_(24.8)Gr_(17.6)),depleted in LREE(0.14-0.69 ppm),enriched in HREE(95.68-841.60 ppm)and have pronounced negative Eu anomalies(δEu=0.24-0.51).In addition,garnets from iron ores of the Huoshenmiao deposit contain abundant daughter mineral-bearing,multiphase fluid inclusions,further confirming their hydrothermal origin.Two samples of those hydrothermal garnets yield U-Pb dates of 437±9 Ma and 437±10 Ma(2σ),revealing a Paleozoic mineralization event that has long been ignored and rarely documented.These garnet dates agree well with zircon U-Pb dates of 438±4 Ma to 436±3 Ma for a gabbroic diorite and 430±4 Ma for a granite intrusion in close proximity of the mine,supporting a possible genetic link between the iron mineralization and Early Silurian magmatism.The Paleozoic intrusions are enriched in large ion lithophile elements(LILEs:Ba,K,Sr)and LREEs,depleted in high field strength elements(HFSEs:Nb,Ta,P,Ti),have whole-rock(^(87)Sr/^(86)Sr)i,ε_(Nd)(t),and zirconεHf(t)values of 0.7039-0.7042,3.32-4.33,and 13.0-14.9,respectively.These geochemical and isotopic characteristics suggest that the Paleozoic intrusions were affiliated with arc magmatism triggered by subduction of the Shangdan oceanic plate in the Early Paleozoic.Recognition of the Silurian Huoshenmiao iron skarn deposit opens a new window for exploration of Paleozoic mineral resources in the Tongbai area and other portions of the North Qinling Orogen.
