The Niutougou gold deposit, located in the center of the Xiong＇ershan gold district, western Henan Province, is a large gold deposit with many quartz porphyries found in the area. Based on the field geological invest...The Niutougou gold deposit, located in the center of the Xiong＇ershan gold district, western Henan Province, is a large gold deposit with many quartz porphyries found in the area. Based on the field geological investigation of quartz porphyry of Niutougou gold deposit and by using the cathodoluminescence （CL） images analysis and in situ LA-ICP-MS U-Pb isotope dating method of zircons, the inner structure, trace element compositions and U-Pb age of the zircons separated from quartz porphyry were analyzed and determined. Cathodoluminescence （CL） images of zircons show clear magmatic zonations. Trace element analyses of zircons reveal that all zircons show high concentrations of Th, U, and HREE, and the REE patterns of depletion in LREE, with a positive Ce anomaly. Zircon LA-ICP-MS U-Pb dating results show that the quartz porphyry in the Niutougou gold deposit was formed at 159.714-0.99 Ma （about 160 Ma）, belonging to the product of magmatic activity in late Middle Jurassic. Combined with the geological characteristics of the Niutougou gold deposit, the formation age of the quartz porphyry and the analysis of the formation age of the granite body exposed in the Niutougou gold deposit, the study suggests that the metallogenic epoch of the Niutougou gold deposit may be Yanshanian in age.展开更多
The eastern margin of the Qaidam Basin lies in the key tectonic location connecting the Qinling, Qilian and East Kunlun orogens. The paper presents an investigation and analysis of the geologic structures of the area ...The eastern margin of the Qaidam Basin lies in the key tectonic location connecting the Qinling, Qilian and East Kunlun orogens. The paper presents an investigation and analysis of the geologic structures of the area and LA-ICP MS zircon U-Pb dating of Paleozoic and Mesozoic magmatisms of granitoids in the basement of the eastern Qaidam Basin on the basis of 16 granitoid samples collected from the South Qilian Mountains, the Qaidam Basin basement and the East Kunlun Mountains. According to the results in this paper, the basement of the basin, from the northern margin of the Qaidam Basin to the East Kunlun Mountains, has experienced at least three periods of intrusive activities of granitoids since the Early Paleozoic, i.e. the magmatisms occurring in the Late Cambrian （493.1±4.9 Ma）, the Silurian （422.9±8.0 Ma-420.4±4.6 Ma） and the Late Permian-Middle Triassic （257.8±4.0 Ma-228.8＋1.5 Ma）, respectively. Among them, the Late Permian - Middle Triassic granitoids form the main components of the basement of the basin. The statistics of dated zircons in this paper shows the intrusive magmatic activities in the basement of the basin have three peak ages of 244 Ma （main）, 418 Ma, and 493 Ma respectively. The dating results reveal that the Early Paleozoic magmatism of granitoids mainly occurred on the northern margin of the Qaidam Basin and the southern margin of the Qilian Mountains, with only weak indications in the East Kunlun Mountains. However, the distribution of Permo-Triassic （P-T） granitoids occupied across the whole basement of the eastern Qaidam Basin from the southern margin of the Qilian Mountains to the East Kunlun Mountains. An integrated analysis of the age distribution of P-T granitoids in the Qaidam Basin and its surrounding mountains shows that the earliest P-T magmatism （293.6-270 Ma） occurred in the northwestern part of the basin and expanded eastwards and southwards, resulting in the P-T intrusive magmatism that ran through the whole basin basement. As the Cenozoic basement thrust system developed in the eastern Qaidam Basin, the nearly N-S-trending shortening and deformation in the basement of the basin tended to intensify from west to east, which went contrary to the distribution trend of N-S-trending shortening and deformation in the Cenozoic cover of the basin, reflecting that there was a transformation of shortening and thickening of Cenozoic crust between the eastern and western parts of the Qaidam Basin, i.e., the crustal shortening of eastern Qaidam was dominated by the basement deformation （triggered at the middle and lower crust）, whereas that of western Qaidam was mainly by folding and thrusting of the sedimentary cover （the upper crust）.展开更多
The Wurinitu molybdenum deposit,located in Honggor,Sonid Left Banner of Inner Mongolia,China,is recently discovered and is considered to be associated with a concealed fine-grained granite impregnated with molybdenite...The Wurinitu molybdenum deposit,located in Honggor,Sonid Left Banner of Inner Mongolia,China,is recently discovered and is considered to be associated with a concealed fine-grained granite impregnated with molybdenite.The wall rocks are composed of Variscan porphyritic-like biotite granite and the Lower Ordovician Wubin'aobao Formation.LA-ICP-MS zircon U-Pb dating of the fine-grained granite reveals two stages of zircons,one were formed at 181.7±7.4 Ma and the other at 133.6±3.3 Ma.The latter age is believed to be the formation age of the fine-grained granite,while the former may reflect the age of inherited zircons,based on the morphological study of the zircon and regional geological setting.The Re-Os model age of molybdenite is 142.2±2.5 Ma,which is older than the diagenetic age of the fine-grained granite.Therefore the authors believe that the metallogenic age of the Wurinitu molybdenum deposit should be nearly 133.6±3.3 Ma or slightly later,i.e.,Early Cretaceous.Combined with regional geological background research,it is speculated that the molybdenum deposits were formed at the late Yanshanian orogenic cycle in the Hingganling-Mongolian orogenic belt,belonging to the relaxation epoch posterior to the compression and was associated with the closure of the Mongolia-Okhotsk Sea.展开更多
基金funded by the Program forthe New Century Excellent Tallents in Ministry of Education (No.NCET-09-0710)the National Natural Science Foundation of China (No.40872068 and40672064)+1 种基金the Program for Changjiang Scholars and Innovative Research Team in Ministry of Education(No.IRT0755)the "111" Project (No.B07011)
文摘The Niutougou gold deposit, located in the center of the Xiong＇ershan gold district, western Henan Province, is a large gold deposit with many quartz porphyries found in the area. Based on the field geological investigation of quartz porphyry of Niutougou gold deposit and by using the cathodoluminescence （CL） images analysis and in situ LA-ICP-MS U-Pb isotope dating method of zircons, the inner structure, trace element compositions and U-Pb age of the zircons separated from quartz porphyry were analyzed and determined. Cathodoluminescence （CL） images of zircons show clear magmatic zonations. Trace element analyses of zircons reveal that all zircons show high concentrations of Th, U, and HREE, and the REE patterns of depletion in LREE, with a positive Ce anomaly. Zircon LA-ICP-MS U-Pb dating results show that the quartz porphyry in the Niutougou gold deposit was formed at 159.714-0.99 Ma （about 160 Ma）, belonging to the product of magmatic activity in late Middle Jurassic. Combined with the geological characteristics of the Niutougou gold deposit, the formation age of the quartz porphyry and the analysis of the formation age of the granite body exposed in the Niutougou gold deposit, the study suggests that the metallogenic epoch of the Niutougou gold deposit may be Yanshanian in age.
基金supports by the Basic Research Foundation of the Institute of Geomechanics,CAGS,China (DZLXJK200703)the National Natural Science Foundation of China(40342015)+1 种基金SinoProbe-Deep Exploration in China(SinoProbe-08)the National Science Foundation(USA) Instrumentation and Facilities Program (EAR-0443387)
文摘The eastern margin of the Qaidam Basin lies in the key tectonic location connecting the Qinling, Qilian and East Kunlun orogens. The paper presents an investigation and analysis of the geologic structures of the area and LA-ICP MS zircon U-Pb dating of Paleozoic and Mesozoic magmatisms of granitoids in the basement of the eastern Qaidam Basin on the basis of 16 granitoid samples collected from the South Qilian Mountains, the Qaidam Basin basement and the East Kunlun Mountains. According to the results in this paper, the basement of the basin, from the northern margin of the Qaidam Basin to the East Kunlun Mountains, has experienced at least three periods of intrusive activities of granitoids since the Early Paleozoic, i.e. the magmatisms occurring in the Late Cambrian （493.1±4.9 Ma）, the Silurian （422.9±8.0 Ma-420.4±4.6 Ma） and the Late Permian-Middle Triassic （257.8±4.0 Ma-228.8＋1.5 Ma）, respectively. Among them, the Late Permian - Middle Triassic granitoids form the main components of the basement of the basin. The statistics of dated zircons in this paper shows the intrusive magmatic activities in the basement of the basin have three peak ages of 244 Ma （main）, 418 Ma, and 493 Ma respectively. The dating results reveal that the Early Paleozoic magmatism of granitoids mainly occurred on the northern margin of the Qaidam Basin and the southern margin of the Qilian Mountains, with only weak indications in the East Kunlun Mountains. However, the distribution of Permo-Triassic （P-T） granitoids occupied across the whole basement of the eastern Qaidam Basin from the southern margin of the Qilian Mountains to the East Kunlun Mountains. An integrated analysis of the age distribution of P-T granitoids in the Qaidam Basin and its surrounding mountains shows that the earliest P-T magmatism （293.6-270 Ma） occurred in the northwestern part of the basin and expanded eastwards and southwards, resulting in the P-T intrusive magmatism that ran through the whole basin basement. As the Cenozoic basement thrust system developed in the eastern Qaidam Basin, the nearly N-S-trending shortening and deformation in the basement of the basin tended to intensify from west to east, which went contrary to the distribution trend of N-S-trending shortening and deformation in the Cenozoic cover of the basin, reflecting that there was a transformation of shortening and thickening of Cenozoic crust between the eastern and western parts of the Qaidam Basin, i.e., the crustal shortening of eastern Qaidam was dominated by the basement deformation （triggered at the middle and lower crust）, whereas that of western Qaidam was mainly by folding and thrusting of the sedimentary cover （the upper crust）.
基金support by China Geological Survey (1212010911028)NSFC(40802020)+1 种基金Ministry of Land and Resources(1212010633902,1212010633903 and 121201 0711814)CUGB(GPMR 0735)
文摘The Wurinitu molybdenum deposit,located in Honggor,Sonid Left Banner of Inner Mongolia,China,is recently discovered and is considered to be associated with a concealed fine-grained granite impregnated with molybdenite.The wall rocks are composed of Variscan porphyritic-like biotite granite and the Lower Ordovician Wubin'aobao Formation.LA-ICP-MS zircon U-Pb dating of the fine-grained granite reveals two stages of zircons,one were formed at 181.7±7.4 Ma and the other at 133.6±3.3 Ma.The latter age is believed to be the formation age of the fine-grained granite,while the former may reflect the age of inherited zircons,based on the morphological study of the zircon and regional geological setting.The Re-Os model age of molybdenite is 142.2±2.5 Ma,which is older than the diagenetic age of the fine-grained granite.Therefore the authors believe that the metallogenic age of the Wurinitu molybdenum deposit should be nearly 133.6±3.3 Ma or slightly later,i.e.,Early Cretaceous.Combined with regional geological background research,it is speculated that the molybdenum deposits were formed at the late Yanshanian orogenic cycle in the Hingganling-Mongolian orogenic belt,belonging to the relaxation epoch posterior to the compression and was associated with the closure of the Mongolia-Okhotsk Sea.
