The Metallogenic Type of the Xiaohuli Shan Molybdenum Polymetallic Ore Deposit in the Beishan Area,Inner Mongolia and Prospecting Direction

The Xiaohuli Shan molybdenum polymetallic ore deposit which was discovered in the Beishan area in recent years is a concealed deposit of a medium-large scale with typical metallogenic features. Its host rocks can be divided into three distinct phases,i. e. the edge phase,transition phase and center phase among which the center phase has strong silicification and potassium feldspathization phenomena and the edge and transition phases have obvious albitization alteration characteristics superimposed by post-magmatic greisenization alteration. The molybdenum ore deposit mainly occurs in the albitization rock zone and greisenized rock zone of the edge phase and transition phase. This molybdenum polymetallic deposit,that formed in Triassic,is the product of the tectonic-magmatic activities in the Indosinian period. Analysis of compound mineralization characteristics of Mo→Pb-Zn→rare metals suggests that it is attributed to a hydrothermal superimposition deposit as a result of magmatic hydrothermal activities in various periods. Combining the analysis of rock geochemistry and tectonic setting and mineralization and alteration characteristics,this ore deposit is considered to be a magmatic hydrothermal superimposition deposit formed in an intraplate extensional tectonic environment.