Abstract: The geotectonic position of the niobium mining area in Dazhuang,Fangcheng County,Henan Province lies across the south margin of the North China landmass and the North Qinling tectonic belt,it is located in the north side of LuanchuanWeimosi fracture.The structure of the earth′s crust is characterized by double layers of basement and caprock.The deposit is controlled by the alkaline rock belt of LuanchuanWeimosi fracture in the region.In order to analyze the geological characteristics and prospecting indicators of the niobium ore,on the basis of previous work and research,this paper summarizes the characteristics of strata、magmatic rock and geophysical and geochemical exploration in the mining area,and summarizes the characteristics of ore body delineation combined with gamma survey,analyzes the geological characteristics and prospecting marks of the area,which can provide reference for further prospecting work.According to the comprehensive analysis,the genetic type of the deposit is magmatic differentiation deposit,and the main ore prospecting indicator is the high alkaline rock mass.

Key words: Gammasurvey, Alkaline rock, Nb deposit, Geological characteristics, Prospecting criteria