Geological Characteristics And Metallogenic Regularities Of Taipingcun Mo Deposit In Xinglong County,Hebei Province

Taipingcun molybdenum mine is located in the magmatic metamorphic complex area in the northwest of the mantle branch structure in eastern Hebei Province.The ore body mainly occurs in the transitional area between the rock body and the metamorphic rock in the outer contact zone.Although many phases of exploration work have been carried out in the mining area,the theoretical summary is weak,and there are still many geological problems,such as the structural research is not systematic enough,the relationship between diagenesis and mineralization is not clear,and the metallogenic and ore controlling factors are not clear.In this paper,the ore deposit has been analyzed through geological data collection,geological survey,stereographic projection analysis,rock ore testing,etc.,and the achievements are as follows:1.The exposed strata in the study area are mainly the Archean Malanyu Formation metamorphic rocks of Zunhua Group.The molybdenum ore body is mainly controlled by the complex joint system and fault structure formed by multiple tectonic magmatic activities.The mineralization types are mainly divided into molybdenite quartz vein type,molybdenite disseminated type and molybdenite thin film(vein)type,mainly quartz vein type.it is defined as“hydrothermal vein type(fine mesh vein type)molybdenum deposit”.2.Through zircon U-Pb isotopic dating,the age of the small granodiorite body is163.2 ± 3.1 Ma.The diagenetic age of granodiorite is consistent with the metallogenic age of molybdenite(162.25±2.5～165.7±2.5)within the error range.Diagenesis and mineralization are almost simultaneous.The small body of granodiorite is closely related to the formation of molybdenum deposit.3.The analysis of major trace elements and rare earth elements shows that the granodiorite is characterized by high silicon,low aluminum,medium total alkali,enrichment of large ion lithophile elements Rb,U,Sr,relative loss of high field strength elements Nb,Ta,etc.,belonging to the weak peraluminous high potassium alkaline rock series;In the Na2O-K2 O diagram,it falls into the I-type granite area,which belongs to I-type granite.It is the crustal material mixed by mantle derived magma and formed by partial melting and fractional crystallization.4.The tectonic stress field evolution of Taipingcun molybdenum deposit can be roughly divided into three stages: pre mineralization,mineralization period and post mineralization.The direction of the maximum principal stress has undergone a process of transformation from nearly north-south(pre mineralization)to northwest southeast(mineralization period),and has experienced post mineralization uplift.The multiple tectonic stress fields in different directions have formed the complex joint system and fault structure in the mining area,provided the main ore hosting space and controlled the spatial distribution of molybdenum mineralization.