青海祁漫塔格长山钼矿地质特征、矿床成因及找矿前景

Geological Features,Deposit Genesis and Prospecting Potential of Changshan Molybdenum Deposit in Qimantage,Qinghai Province

长山钼矿位于青海省东昆仑西段祁漫塔格地区,在以往发现接触交代型铁矿体的基础上,近年来发现了花岗斑岩及斑岩型钼矿。斑岩型钼矿的发现,对于东昆仑西段祁漫塔格地区斑岩成矿研究和矿产勘查实践具有重要的意义。在初步研究长山矿区侵入岩分布、岩石类型、岩石学和岩石化学的基础上,发现矿区花岗斑岩呈岩枝状侵入于似斑状二长花岗岩中,地表出露面积小于0.01km2,深部揭露最大厚度可达30m,岩石具有高Si,低Ti,K/Na值大,分异程度高,固结程度低的特征。与西藏冈底斯钾质钙碱性花岗岩和含矿斑岩具有相似的岩石化学特征,但SiO2含量更高,Al2O3含量较低。综合分析认为,矿区花岗斑岩可能与碰撞后伸展构造背景密切相关。矿区钼矿具有斑岩型成矿的特点,矿区中西部的深部及区域具有进一步寻找斑岩型矿产的前景。

Changshan molybdenum deposit is located in Qimantage area of western East Kunlun of Qinghai province. In the past, Changshan deposit was a contact metasomatic iron deposit. Recently, some granite porphyries and porphyry molybdenum mines have been found, which has great significance for metallogenic study and mineral exploration of Qimantage area. Based on studying distribution, rock types, petrology and petrochemistry of intrusive rocks, the result has been achieved as follows. These granite porphyries are some apophyses intruded into porphyritic monzogranite. The outcrop area of granite porphyries is less than 0.01 km2 and the biggest thickness are 30 meters. These rocks have the features of higher SiO2 content, lower TiO2 content, bigger ratio of K2O and Na2O, higher differentiation and lower consolidation. They are similar with potassic calc alkaline granite and mineralization porphyry rocks of Tibet Gangdise in petrochemistry feature, except for the higher SiO2 and the lower Al2O3. They are possibly related to extension of post-collision tectonic. The genesis of Changshan molybdenum deposit is considered as porphyry-type. There are better prospecting potential in mid-west Changshan deposit and Qimantage region.