北京万庄金矿床成矿特征及成因探讨

北京平谷万庄金矿产于燕山沉降带内的中元古界碳酸盐岩中，金矿化受燕山期三百山岩体、变质地层、层间虚脱构造及多期活动的NE走向断裂构造控制。金矿体呈筒状、扁担状及脉状产出。矿石矿物以褐铁矿、黄铁矿、自然金、银金矿为主。矿石类型主要有硅化多金展硫化物型和硅化黄铁矿型。矿区内矿化水平分带性明显。自三百山岩体为中心，从岩体内部到接触带，再到外接触带的变质地居中，依次发育有热液脉型铜矿化、夕卡岩铜金矿化和热液型金矿化，其中前两者未形成县有工业意又的矿床，仅第三者形成具有工业意又的万庄金矿床。矿区内大古界密云群基底变质岩为万庄金矿的形成提供了部分矿源，三百山闪长玢岩及石英闪长岩为成矿提供了热源和部分含矿热液，并与循环大气水混合促进了金的沉淀。中元古代长城系碳酸盐岩成为金矿化的有利围岩。万庄金矿为一层控特征明显的中低温热液型金矿床。

STUDY ON THE METALLOGENIC FEATURE AND ORE GENESIS OF WANZHUANG GOLD DEPOSIT, BEIJING

Wanzhuang gold deposit is distributed in the Midproterozoic ca rbonate strata of the Yanshan depression zone within the Sino-Korean platform. G old mineralization is controlled by the Yan- shanian period Sanbaishan intr usive, metamorphosed strata, interformational breccia zones and NE-striked fract ures with multi-period of activities. Gold ore bodies in Wanzhuang gold deposit occur as chimney, pillar and vein forms. The main ore minerals are limonite, pyr ite, native gold, and electrum. Ore types are mainly silicalized poly-metallic a nd silicalized pyrite types. In the mining area, horizontal mineralization zonat ion is obvious. Taking Sanbaishan intrusive as the center outwardly through inne r contact zone to outer contact zone and the metamorphic wall rocks, mineraliza tion types change from hydrothermal vein type Cu mineralization to skarn type Cu -Au mineralization to hydrothermal gold mineralization. The first two types of m ineralization are of no industrious significance while the third ore forms Wanzh uang gold deposit. Various pieces of evidence shows that the basement rocks of the Archean Miyun group provided some ore-forming materieds and the Sanbaishan q uartz diorite intrusive and related dykes could be the source for heat and part of the ore-forming hydrothermal fluid that mixed with meteoric water during gold mineralization. And the Midproterozoic carbonate rocks were the favourable wall rocks for gold mineralization. From all above, it is recognized that Wanzhuang gold deposit belongs to the type of middle to low temperature gold deposit with obvious stratabound characteristics.