The Qinling Orogen in Central China records the history of a complex geological evolution and tectonic transition from compression to extension during the Late Mesozoic,with concomitant voluminous granitoids formation...The Qinling Orogen in Central China records the history of a complex geological evolution and tectonic transition from compression to extension during the Late Mesozoic,with concomitant voluminous granitoids formation.In this study,we present results from petrological,geochemical,zircon U-Pb-Lu-Hf isotopic studies on the Lengshui felsic dykes from Luanchuan region in the East Qinling Orogen.We also compile published geochronological,geochemical,and Hf isotopic data from Luanchuan region and present zircon Hf isotopic contour maps.The newly obtained age data yield two group of ages at w145 Ma and 140 Ma for two granite porphyries from the Lengshui felsic dykes,with the w145 Ma interpreted as response to the peak of magmatism in the region,and the w140 Ma as the timing of formation of the felsic dykes.The corresponding Hf isotopic data of the granite porphyries display negative εHf(t) values of e16.67 to e4.61,and Hf crustal model ages (TDM^C) of 2255e1490 Ma,indicating magma sourced from the melting of Paleo- to Mesoproterozoic crustal materials.The compiled age data display two major magmatic pulses at 160e130 Ma and 111e108 Ma with magmatic quiescence in between,and the zircon Hf isotopic data display εHf(t) values ranging from e41.9 to 2.1 and TDM^C values of 3387e1033 Ma,suggesting mixed crustal and mantle-derived components in the magma source,and correspond to multiple tectonic events during the Late Mesozoic.The Luanchuan granitoids are identified as I-type granites and most of these are highly fractionated granites,involving magma mixing and mingling and crystal fractionation.The tectonic setting in the region transformed from the Late Jurassic syn-collision setting to Early Cretaceous within-plate setting,with EeW extension in the Early Cretaceous.This extension is correlated with the NeS trending post-collisional extension between the North China Craton and Yangtze Craton as well as the EeW trending back-arc extension triggered by the westward Paleo-Pacific Plate subduction,eventually leading to lithospheric thinning,asthenospheric upwelling,mafic magma underplating,and crustal melting in the East Qinling Orogen.展开更多
The Hongdonggou Pb-Zn polymetallic ore deposit, located in the southwestern part of the Luanchuan Mo-W-Pb-Zn-Ag polymetallic ore mineralization in Henan Province, China, is an important part of the East Qinling metall...The Hongdonggou Pb-Zn polymetallic ore deposit, located in the southwestern part of the Luanchuan Mo-W-Pb-Zn-Ag polymetallic ore mineralization in Henan Province, China, is an important part of the East Qinling metallogenic belt. The orebodies in the deposit, which are vein, bedded and lenticular, are mainly hosted in the syenite porphyry, and formed within the carbonate and clastic rocks of the Yuku and Qiumugou formations partially. The genesis of the deposit has previously been argued to be of hydrothermal-vein type or of skarn-hydrothermal type. In this study, we report the results of Rb-Sr isotopic dating based on sphalerites from the main orebody of the Hongdonggou Pb-Zn polymetallic ore deposit, which yield an isochron age of 135.7 ± 3.2 Ma, constraining the timing of mineralization as early Cretaceous. The age is close to those reported for the Pb-Zn deposits in the Luanchuan ore belt. The （87Sr/86Sr）i values of the sphalerites （0.71127± 0.00010） are lower than that of terrigenous silicates （0.720） and higher than the mantle （0.707）, suggesting that the metallogenic components were mainly derived through crust-mantle mixing. Combining the results from this study with those from previous work, we propose that the Hongdonggou Pb-Zn polymetallic ore deposit is a hydrothermal-vein deposit associated with the early Cretaceous tectonothermal event, and the mineralization is controlled by NW- and near EW-trending faults in the Luanchuan Mo-W-Pb-Zn-Ag polymetallic ore concentration belt.展开更多
基金jointly supported by the Fundamental Research Funds for the Central Universities (Grant No.2652016066)China Scholarship Council (Grant Nos.201706400016, 201806400026)+2 种基金Basic Research Project (GP2017021Development of integrated geological information based on digital mapping) of the Korea Institute of Geoscience and Mineral Resourcesfunded by the Ministry of Science, ICT,Future Planning
文摘The Qinling Orogen in Central China records the history of a complex geological evolution and tectonic transition from compression to extension during the Late Mesozoic,with concomitant voluminous granitoids formation.In this study,we present results from petrological,geochemical,zircon U-Pb-Lu-Hf isotopic studies on the Lengshui felsic dykes from Luanchuan region in the East Qinling Orogen.We also compile published geochronological,geochemical,and Hf isotopic data from Luanchuan region and present zircon Hf isotopic contour maps.The newly obtained age data yield two group of ages at w145 Ma and 140 Ma for two granite porphyries from the Lengshui felsic dykes,with the w145 Ma interpreted as response to the peak of magmatism in the region,and the w140 Ma as the timing of formation of the felsic dykes.The corresponding Hf isotopic data of the granite porphyries display negative εHf(t) values of e16.67 to e4.61,and Hf crustal model ages (TDM^C) of 2255e1490 Ma,indicating magma sourced from the melting of Paleo- to Mesoproterozoic crustal materials.The compiled age data display two major magmatic pulses at 160e130 Ma and 111e108 Ma with magmatic quiescence in between,and the zircon Hf isotopic data display εHf(t) values ranging from e41.9 to 2.1 and TDM^C values of 3387e1033 Ma,suggesting mixed crustal and mantle-derived components in the magma source,and correspond to multiple tectonic events during the Late Mesozoic.The Luanchuan granitoids are identified as I-type granites and most of these are highly fractionated granites,involving magma mixing and mingling and crystal fractionation.The tectonic setting in the region transformed from the Late Jurassic syn-collision setting to Early Cretaceous within-plate setting,with EeW extension in the Early Cretaceous.This extension is correlated with the NeS trending post-collisional extension between the North China Craton and Yangtze Craton as well as the EeW trending back-arc extension triggered by the westward Paleo-Pacific Plate subduction,eventually leading to lithospheric thinning,asthenospheric upwelling,mafic magma underplating,and crustal melting in the East Qinling Orogen.
基金supported by the National Science and Technology Support Project of the 12th"Five-Year Plan"(Grant No.2011BAB04B06)the Fundamental Research Funds for the Central Universities of China University of Geosciences,Beijing(Grant No.2-9-2012-143)the National Natural Science Foundation of China(Grant No.41572318)
文摘The Hongdonggou Pb-Zn polymetallic ore deposit, located in the southwestern part of the Luanchuan Mo-W-Pb-Zn-Ag polymetallic ore mineralization in Henan Province, China, is an important part of the East Qinling metallogenic belt. The orebodies in the deposit, which are vein, bedded and lenticular, are mainly hosted in the syenite porphyry, and formed within the carbonate and clastic rocks of the Yuku and Qiumugou formations partially. The genesis of the deposit has previously been argued to be of hydrothermal-vein type or of skarn-hydrothermal type. In this study, we report the results of Rb-Sr isotopic dating based on sphalerites from the main orebody of the Hongdonggou Pb-Zn polymetallic ore deposit, which yield an isochron age of 135.7 ± 3.2 Ma, constraining the timing of mineralization as early Cretaceous. The age is close to those reported for the Pb-Zn deposits in the Luanchuan ore belt. The （87Sr/86Sr）i values of the sphalerites （0.71127± 0.00010） are lower than that of terrigenous silicates （0.720） and higher than the mantle （0.707）, suggesting that the metallogenic components were mainly derived through crust-mantle mixing. Combining the results from this study with those from previous work, we propose that the Hongdonggou Pb-Zn polymetallic ore deposit is a hydrothermal-vein deposit associated with the early Cretaceous tectonothermal event, and the mineralization is controlled by NW- and near EW-trending faults in the Luanchuan Mo-W-Pb-Zn-Ag polymetallic ore concentration belt.
