Abstract: Taking Barenzhalage UNb deposit in Inner Mongolia as the study example,the reason the the the logging interpretation results is interfered by Th radioactive,the computation method of Th interference modification coefficient of gamma ray logging is discussed,besides that,the distribution characteristics of Th interference modification coefficient of gamma ray logging is studied based on the analysis of the alteration characteristics of orebodies or rock mass bodies and orebody depth.The calculation method of thorium interference modification coefficient of gamma ray logging proposed in this paper can provide some reliable reference for the radioactive logging data modification,division of orebody boundary and calculation of uranium resources reserves of Barenzhalage UNb deposit in Inner Mongolia.

Key words: Nb deposit, Th interference modification coefficient, Gamma ray logging interpretation