大别山北麓姚冲钼矿床地质特征及找矿标志

河南省新县姚冲钼矿床是大别山北麓新发现的又一典型的斑岩型钼矿床,目前控制规模为中型。矿体主要赋存于花岗斑岩体(脉)外接触带(中元古界蚀变片麻岩),受隐伏岩体和构造控制。辉钼矿化呈浸染状、细脉-网脉状、薄膜状和角砾状产出。围岩蚀变主要有硅化、钾长石化、黄铁矿化、绢云母化、绿泥石化、绿帘石化、方解石化、萤石化和高岭土化等,具典型斑岩型钼矿床的矿化和围岩蚀变特征。其中硅化和钾长石化与钼成矿关系密切。矿床蚀变分带明显,由中心向外侧依次为钾长石化-硅化带(强蚀变带)、硅化-绢英岩化带(弱蚀变带)、硅化-青磐岩化带,由中心向外围蚀变强度逐渐变弱。蚀变作用的强弱与钼矿体的品位高低相对应,硅化和钾化为该区最直接的找矿标志之一。

Geological features and ore-searching indicators of the Yaochong Mo deposit in the northern Piedmont of the Dabie Shan

Abstract: The Yaochong Mo deposit in Xin County, Henan Province is a newly discovered porphyry Mo deposit in the northern piedmont of the Dabie Shan, with a medium size confirmed at present. The orebodies occur in the exomorphic zone of cryptobatholithic porphyry and are controlled by the hidden rock bodies and structures. The molybdenite displays disseminated, veinlet, film or breccia structures. Hydrothermal alteration includes silicification, potassic alteration, sericitization, chloritization, epidotization, carbonatization, fluorization and kaolinizaton, indicating typical porphyry deposit features. The silicification and potassic alteration are intimately associated with the Mo mineralization. The clear alteration is zoned outward from the central potassic-silicic alteration to broader envelops of silicic-sericitic and to silici-propylitic zones. The alteration becomes weak outward and corresponds to the ore grades. The silicification and potassic alteration can be regarded as direct ore-searching indicators in this area.