Zircon U-Pb ages and geochemical analytical results are presented for the volcanic rocks of the Naozhigou, Ergulazi, and Sidaogou Formations in the Linjiang area, southeastern Jilin Province to constrain the nature of...Zircon U-Pb ages and geochemical analytical results are presented for the volcanic rocks of the Naozhigou, Ergulazi, and Sidaogou Formations in the Linjiang area, southeastern Jilin Province to constrain the nature of magma source and their tectonic settings. The Naozhigou Formation is composed mainly of andesite and rhyolite and its weighted mean ^206pb/^238U age for 13 zircon grains is 222±1 Ma. The Ergulazi Formation consists of basaltic andesite, basaltic trachyandesite, and andesite, and six grains give a weighted mean ^206pb/^238U age of 131±4 Ma. The Sidaogou Formation consists mainly of trachyandesite and rhyolite, and six zircon grains yield a weighted mean ^206pb/^238U age of 113±4 Ma. The volcanic rocks have SIO2=60.24%-77.46%, MGO=0.36%-1.29% （Mg#=0.32-0.40） for the Naozhigou Formation, SIO2=51.60%-59.32%, MGO=3.70%-5.54% （Mg#=0.50-0.60） for the Ergulazi Formation, and SIO2=58.28%-76.32%, MGO=0.07%-1.20% （Mg#=0.14-0.46） for the Sidaogou Formation. The trace element analytical results indicate that these volcanic rocks are characterized by enrichment in light rare earth elements （LREEs） and large ion lithophile elements （LILEs）, relative depletion in heavy rare earth elements （HREEs） and high field strength elements （HFSEs, Nb, Ta, and Ti）, and negative Eu anomalies. Compared with the primitive mantle, the Mesozoic volcanic rocks in the Linjiang area have relatively high initial ^87Sr/^86Sr ratios （0.7053-0.7083） and low εNd（t） values （-8.38 to -2.43）, and display an EMⅡ trend. The late Triassic magma for the Naozhigou Formation could be derived from partial melting of a newly accretional crust with the minor involvement of the North China Craton basement and formed under an extensional environment after the collision of the Yangtze Craton and the North China Craton. The Early Cretaceous volcanic rocks for the Ergulazi and Sidaogou Formations could be formed under the tectonic setting of an active continental margin related to the westward subduction of the Izanagi plate.展开更多
The Liudaogou area underwent multiple large-scale tectonic movements since Archean. Little studies have been carried out on the age of Mesozoic magmatism and petrogenesis in the area. Zircon U-Pb geochronology and geo...The Liudaogou area underwent multiple large-scale tectonic movements since Archean. Little studies have been carried out on the age of Mesozoic magmatism and petrogenesis in the area. Zircon U-Pb geochronology and geochemistry of the Liudaogougranodiorite were undertaken in this study to determine the forming-age of the granodiorite and to understand its petrogenesis and tectonic background of diagenesis. Zircon in the rock samples show good idiomorphic and obvious rhythmic growth girdle zone,belonging to typical magmatic zircon.Zircon LA-ICP-MS U-Pb dating results show that the emplacement of rock mass occurred in late Early Cretaceous( 125 ± 1 Ma,MSWD = 0. 53). The geochemical data show that the rock belongs to quasi-aluminous granite of type I which has the properties of high potassium calc-alkaline adakite,with A/CNK ratio of 0. 82--0. 98( < 1. 1). The rock shows obvious enrichment of LILE and LREE but depletion of HFSE,and is characterized by high Sr( 374. 9 × 10^(-6)--777. 6 × 10^(-6)) and low Y( 8. 84 × 10^(-6)--12. 4 × 10^(-6)). The samples are rich in Si,and the K_2 O/Na_2 O ratio( 0. 99--1. 30) is very high,indicating that magma might have originated from melting upper crust. The high content of Mg~#( 49. 68--56. 92) in the samples implies that mantle-derived materials might have involved in magma. It can be concluded that in the process of delamination,the lower crust sank,and was heated by asthenosphere mantle,and partially melted. The primitive magma should be the mixture of the mantle-derived magma and the partially melting lower crust. Integrating research results on the regional contemporary igneous rock,it can be concluded that the rocks were formed in an active continental margin environment related to the subduction of the Paleo-Pacific Plate to the Eurasian Plate.展开更多
The concept of "renovation and restoration" marks the transformation from urban and rural planning and construction to intensive development mode and to quality improvement stage.The environmental imbalance ...The concept of "renovation and restoration" marks the transformation from urban and rural planning and construction to intensive development mode and to quality improvement stage.The environmental imbalance problem of emphasizing development and neglecting ecology in the past has become the focus of the current urban quality improvement stage.Rivers are related to the origin,development and evolution of cities,affect the layout,transportation and environment of cities,and bear the culture,economy and characteristics of cities.Taking the Linjing River of Yongchuan in Chongqing as an example and taking the concept of "renovation and restoration" as the guidance of the design of the overall environmental quality improvement of the river,this study analyzed and summarized the problems to be solved in the improvement of the environmental quality of the river based on the four river environmental impact factors of water pollution,water resource supply and demand,ecological environment and shore water waterfront type and the strategies of optimizing the aquatic environment management,constructing the ecological landscape pattern,shaping the regional cultural landscape and combining the economic development along the river were put forward in order to improve the overall environmental quality of Linjiang River and provide reference for relevant planning and design.展开更多
With the rapid development of remote sensing technology, it has become a technical means of geological research and geological survey. Remote sensing can realize rapid and large area information extraction and provide...With the rapid development of remote sensing technology, it has become a technical means of geological research and geological survey. Remote sensing can realize rapid and large area information extraction and provide effective method for geological hazard extraction. However, due to regional differences, there are some differences between geological hazard occurrence characteristics and extraction indexes in different regions. This paper takes Linjiang City, Jilin Province as an example to extract geological hazards with multisource data. The results show that the remote sensing method can realize the extraction of debris flow, collapse, landslide and other geological hazards in the study area, and obtain high accuracy.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.40672038).
文摘Zircon U-Pb ages and geochemical analytical results are presented for the volcanic rocks of the Naozhigou, Ergulazi, and Sidaogou Formations in the Linjiang area, southeastern Jilin Province to constrain the nature of magma source and their tectonic settings. The Naozhigou Formation is composed mainly of andesite and rhyolite and its weighted mean ^206pb/^238U age for 13 zircon grains is 222±1 Ma. The Ergulazi Formation consists of basaltic andesite, basaltic trachyandesite, and andesite, and six grains give a weighted mean ^206pb/^238U age of 131±4 Ma. The Sidaogou Formation consists mainly of trachyandesite and rhyolite, and six zircon grains yield a weighted mean ^206pb/^238U age of 113±4 Ma. The volcanic rocks have SIO2=60.24%-77.46%, MGO=0.36%-1.29% （Mg#=0.32-0.40） for the Naozhigou Formation, SIO2=51.60%-59.32%, MGO=3.70%-5.54% （Mg#=0.50-0.60） for the Ergulazi Formation, and SIO2=58.28%-76.32%, MGO=0.07%-1.20% （Mg#=0.14-0.46） for the Sidaogou Formation. The trace element analytical results indicate that these volcanic rocks are characterized by enrichment in light rare earth elements （LREEs） and large ion lithophile elements （LILEs）, relative depletion in heavy rare earth elements （HREEs） and high field strength elements （HFSEs, Nb, Ta, and Ti）, and negative Eu anomalies. Compared with the primitive mantle, the Mesozoic volcanic rocks in the Linjiang area have relatively high initial ^87Sr/^86Sr ratios （0.7053-0.7083） and low εNd（t） values （-8.38 to -2.43）, and display an EMⅡ trend. The late Triassic magma for the Naozhigou Formation could be derived from partial melting of a newly accretional crust with the minor involvement of the North China Craton basement and formed under an extensional environment after the collision of the Yangtze Craton and the North China Craton. The Early Cretaceous volcanic rocks for the Ergulazi and Sidaogou Formations could be formed under the tectonic setting of an active continental margin related to the westward subduction of the Izanagi plate.
基金Supported by Project of Geological Exploration Foundation of Jilin Province(No.22201300111)
文摘The Liudaogou area underwent multiple large-scale tectonic movements since Archean. Little studies have been carried out on the age of Mesozoic magmatism and petrogenesis in the area. Zircon U-Pb geochronology and geochemistry of the Liudaogougranodiorite were undertaken in this study to determine the forming-age of the granodiorite and to understand its petrogenesis and tectonic background of diagenesis. Zircon in the rock samples show good idiomorphic and obvious rhythmic growth girdle zone,belonging to typical magmatic zircon.Zircon LA-ICP-MS U-Pb dating results show that the emplacement of rock mass occurred in late Early Cretaceous( 125 ± 1 Ma,MSWD = 0. 53). The geochemical data show that the rock belongs to quasi-aluminous granite of type I which has the properties of high potassium calc-alkaline adakite,with A/CNK ratio of 0. 82--0. 98( < 1. 1). The rock shows obvious enrichment of LILE and LREE but depletion of HFSE,and is characterized by high Sr( 374. 9 × 10^(-6)--777. 6 × 10^(-6)) and low Y( 8. 84 × 10^(-6)--12. 4 × 10^(-6)). The samples are rich in Si,and the K_2 O/Na_2 O ratio( 0. 99--1. 30) is very high,indicating that magma might have originated from melting upper crust. The high content of Mg~#( 49. 68--56. 92) in the samples implies that mantle-derived materials might have involved in magma. It can be concluded that in the process of delamination,the lower crust sank,and was heated by asthenosphere mantle,and partially melted. The primitive magma should be the mixture of the mantle-derived magma and the partially melting lower crust. Integrating research results on the regional contemporary igneous rock,it can be concluded that the rocks were formed in an active continental margin environment related to the subduction of the Paleo-Pacific Plate to the Eurasian Plate.
基金Sponsored by Social Science Planning Project of Chongqing(2019YBSH085)Graduate Education Innovation Fund Project of Chongqing Jiaotong University(2018S0143)Graduate Education Innovation Fund Project of Chongqing Jiaotong University(2019S0101)
文摘The concept of "renovation and restoration" marks the transformation from urban and rural planning and construction to intensive development mode and to quality improvement stage.The environmental imbalance problem of emphasizing development and neglecting ecology in the past has become the focus of the current urban quality improvement stage.Rivers are related to the origin,development and evolution of cities,affect the layout,transportation and environment of cities,and bear the culture,economy and characteristics of cities.Taking the Linjing River of Yongchuan in Chongqing as an example and taking the concept of "renovation and restoration" as the guidance of the design of the overall environmental quality improvement of the river,this study analyzed and summarized the problems to be solved in the improvement of the environmental quality of the river based on the four river environmental impact factors of water pollution,water resource supply and demand,ecological environment and shore water waterfront type and the strategies of optimizing the aquatic environment management,constructing the ecological landscape pattern,shaping the regional cultural landscape and combining the economic development along the river were put forward in order to improve the overall environmental quality of Linjiang River and provide reference for relevant planning and design.
文摘With the rapid development of remote sensing technology, it has become a technical means of geological research and geological survey. Remote sensing can realize rapid and large area information extraction and provide effective method for geological hazard extraction. However, due to regional differences, there are some differences between geological hazard occurrence characteristics and extraction indexes in different regions. This paper takes Linjiang City, Jilin Province as an example to extract geological hazards with multisource data. The results show that the remote sensing method can realize the extraction of debris flow, collapse, landslide and other geological hazards in the study area, and obtain high accuracy.
