534铀矿床地质特征及成矿条件探讨

A STUDY ON GEOLOGICAL CHARACTERISTICS AND METALLOGENETIC CONDITION OF URANIUM DEPOSIT NO.534

534矿床位于华北地台北缘,是一个火山热液型铀矿床。矿化具有明显的垂直分带特征,上部为似层状、层状黑色浸染状铀钼矿体,下部为透镜状、不规则状红色脉状铀矿体。围岩蚀变强烈,主要有水云母化、萤石化、硅化和赤铁矿化。控矿条件:上侏罗统张家口组酸性火山岩含铀丰度高,是矿源层;矿化与燕山中期的次流纹斑岩有关;有利于成矿的多次热液活动;矿区内发育的堑垒束和微裂隙带分别是矿带定位和容矿构造。在隐伏次流纹斑岩体接触带寻找陡倾斜的脉状铀矿化和沿堑垒间的断裂系统追索新的矿化地段是该矿区今后的主要找矿方向。

Uranium deposit No.534 occurs at the north margin of North China Platform, and is a volcanic hydrothermal deposit. The mineralization is characterized by obvious vertical zoning, the upper ore body is stratoid, stratiform and occurs as black disseminated UMo ore; the lower ore body is lenticular, irregular in form, composed of red, vein-like uranium ore. The wall rock alteration is intense, mainly appears as hydromicazation, fluoritization, silicification and hematitization. The ore-controlling conditions of the deposit are: (a) The Upper Jurassic acidic volcanic rock of Zhangjiakou Formation with higher uranium abundance is supposed to be the uranium source-bed; (b) Mineralization is closely related to subrhyolite-porphyry of the middle stage of Yanshan cycle; (c) Multiple hydrothermal activity favourable for mineralization; (d) The graben-horst system and microfissure zones developed in mining area are respectively localization of uranium deposit and ore-hosting structure. The major direction for uranium exploration is to look for steeplydipping and vein-like uranium mineralization at the contact zone of concealed subrhyolite-porphyry and new mineralized area along fault system between graben and horst.