东秦岭地区钼矿床研究现状及存在问题

秦岭造山带北部和华北地台南缘的豫西地区是中国重要的钼多金属和贵金属成矿带之一。前人的研究认为该区钼矿床形成于233～221Ma、148～138Ma和131～112Ma等3期。本文通过对研究区的钼矿床类型及其产出的大地构造环境、岩浆岩类型及时代以及钼矿床形成年代等方面的总结,认为233～221Ma时期的钼矿床产于陆内拉伸环境,可能与同期碱性岩体有关。从Pb、Sr、Nd同位素组成看,成矿物质可能来源于秦岭造山带中的东坡组,成矿元素组成相对简单,以伴生Pb和Au为特征。148～138Ma期间的钼矿床可能形成于地壳加厚的过程中,其形成与以地壳物质为主的重熔型或I型钙碱性岩体有关,岩体Sr、Ba含量较高,伴生成矿元素主要为Fe和W。131～112Ma时期的钼矿床形成于地壳减薄的环境中,与中国东部岩石圈的拆沉、软流圈上涌等过程有关的钾质、高钾或碱性花岗质岩石相关,成矿元素组合局部富W。

Present status of research on molybdenum deposit in eastern Qinling and the problems remained

Western Henan located between the northern Qinling orogenic belt and the southern North China platform,is one of the important molybdenum polymetallic and precious metal metallogenic belts in China. The previous work suggested that molybdenum deposits in the area are occurred in three stages,including 233 ～ 221 Ma, 148 ～ 138 Ma and 131 ～ 112 Ma. The authors summarized the types of molybdenum deposits and their tectonic setting,types and age of magmatic rocks,and age of molybdenum deposits,and considered that the molybdenum deposits in the first stage occurred in continental extensional setting,and their formation possibly associated with its contemporary alkaline rocks. The metallogenic materials are likely originated from Dongpo Formation in Qinling orogenic belt based on the isotopes of Pb,Sr and Nd. The metallogenic elements are relatively simple,characterized by Pb or Au. The second staged deposits are possibly formed in the process of crust thickening,the remelting type and calc-alkaline rocks type I and the associated mainly with Fe and W. The third staged deposits formed in crustthinning setting,and the formation associated with potassium,high potassium or alkaline granitic rocks related to the lithosphere delamination and the upwelling of asthenosphere in eastern China. Metallogenic element is locally enriched W.