北山地区小狐狸山钼多金属矿床成矿类型探讨及其找矿方向

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

小狐狸山钼多金属矿床是近年来在北山地区发现的一个中-大型规模的隐伏钼矿床,具有典型的成矿特征。该矿床的赋矿岩体可以明显的划分为三个相带,即边缘相、过渡相和中心相。岩体中心相具强硅化、钾长石化现象,过渡相和边缘相具有明显的钠长石化蚀变特征,并叠加有岩浆期后云英岩化蚀变现象。钼矿体主要产于岩体过渡相和边缘相的钠长石化带和云英岩化带中。小狐狸山钼多金属矿床成矿时代为三叠纪,属印支期构造-岩浆活动的产物。通过对Mo→Pb-Zn→稀有金属的复合矿化特征分析,推测该矿床可能属于不同期次岩浆热液活动形成的热液叠加矿床。结合岩石地球化学、构造环境及其矿化、蚀变特征分析,该矿床应为板内伸展构造环境下形成的高-中温岩浆热液叠加型矿床。

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.