Characteristics And Geological Significance Of Mesozoic Granites In Liaodong Peninsula-Take Dandong As An Example

The large-scale thinning and destruction of the lithosphere in the Yanshanian period of the North China Craton is one of the major historical events in the evolution of the entirely earth,and it is also the main factor for the frequent scale of magmatic activity of the development of numerous metal hydrothermal deposits.Exploring the cause about the failure mechanism and determining the boundary of time and space has always been a matter that the whole geological science research has failed to achieve.The study area is located in the Dandong area of the Liaodong Peninsula,which is also a typical area of craton damage.Mesozoic magmatic rocks are exposed on a large scale in the area.After field investigation of the entire Dandong area,this paper selects different locations,and choose more typical granite intrusions for petrology,petrography,chronology,geochemitry and other scientific researches,and discusse of the metallogenic event model derived from the Mesozoic in Dandong area.The granite in the area are dominated by biotite monzonitic and monzonitic granite.According to three sets of zircon U-Pb dating data,they are 165.5±1.1 Ma,141.9±0.9Ma,and 124.6±2.5 Ma in order.There are three stages of age,followed by the Middle Jurassic,Late Jurassic,and Early Cretaceous.The main element of the granites in the region are basically of the high potassium calc-alkaline serious of quasi-aluminum rocks,with the characteristics of type I granites.The trace spider web diagram shows that the regional granite of enriched in LREE and depleted in HREE.The obvious negative about Eu anomaly indicates that the plagioclase remains in thegranite source.The diagenetic material of the Wulongbei granite body and the Yalujiang fault zone granite body in the area are derived from crustal materials.This diagenetics materials of the three-streams granite body about derived from the assimilation and contamination of crust mantle magmatic rock.The granite intrusion of three streams about the subduction and collision compression the paleo-Pacific oceanic crust blocks to the Asian continental crust,and the granite intrusions of the Yalujiang fault zones are formed in the tectonics setting of intracontinental extension.