山东沂沭断裂带中段金矿床地质特征

沂水-汤头断裂具有控、容矿构造之特点,金矿的定位经历了复杂的过程,它产于沂水-汤头断裂主裂面下盘的绿泥片岩、糜棱岩化碎裂岩和花岗质碎裂岩中.矿体总体形态较为简单,其产状与主裂面产状一致,局部沿与脆-韧性剪切带斜交的一组裂隙充填交代而成.钾化、黄铁绢英岩化、绿泥石化、绿帘石化为主要找矿标志,矿体的圈定几乎全凭样品分析结果来进行.有用矿物以银金矿为主,自然金次之,裂隙金和晶隙金是其主要的赋存状态,黄铁绢英岩化与金矿关系密切.金矿床的主成矿期为晚侏罗世-早白垩世.根据区域成矿地质条件分析,沿沂水-汤头断裂有良好的找矿前景.

GEOLOGICAL CHARACTERISTIC OF GOLD DEPOSITS IN THE MIDDLE SECTION OF THE YI-SHU FAULT BELT

The Yishui-Tangtou fault is a ore-controlling and hosting structure. Locating of gold deposits in the fault experienced a complicated history. The deposits are located in chlorite schist,mylonitic fragementals and granitic cataclasites in the lower part of major section in the Yishui-Tangtou fault. The occurrence of orebodies were relatively simple,and consistent with the occurrence of major fault section. In some areas,the orebodies were formed by filling and metasomatism along brittle ductile shear belt. Potassic alteration,pyritization-sericitization,chloritization and epidotization are major ore-prospecting symbol. Outlining of orebodies is carried out according to sample analytical results. In useful minerals,electrum is majority and native gold is minority. Gold occur mainly as fissure-filling and crystal crack-filling. Pyritization-sericitization alteration has a close relation with gold mineralization. Major ore-forming period of gold is in late Jurassic to early Cretaceous. Based on regional geological condition,there is a good ore-forming future along the Yishui-Tangtou fault.