额尔古纳地区中生代应力场演化及其与金铅锌矿的关系

STRESS FIELD EVOLUTION IN MESOZOICERA IN ERGUN REGION AND ITS RELATIONSHIP TO GOLDLEADZINC ORE DEPOSITS

额尔古纳地区中生代主要受到３期区域应力场的影响，分别是印支期（Ｔ２—Ｊ１）、塔木兰沟期（Ｊ３）和上库力期（Ｋ１）．印支期的主压应力方位为北北西南南东向，该期应力场在区内形成两条大型韧性剪切带，剪切带走向０～２０°；塔木兰沟的主压应力方位为北西西南东东向，形成了区域上极为发育的两组共轭剪节理，其走向分别为６６～９０°和３２０～３４０°；上库力期的主压应力方位为北北东南南西，它使塔木兰沟期的两组共轭节理复活，形成劈理带、逆断层等．本地区金、铅锌矿点、矿化点或矿化异常区较多．矿（化）体产状与塔木兰沟期、上库力期构造特征相吻合，它们的形成时间基本一致．塔木兰沟期、上库力期强烈的火山作用及其地球化学特征反映当时具有良好的成矿地球化学条件，说明该地区中生代的主成矿期为塔木兰沟期和上库力期．本区已知的金矿（化）点、砂金矿点均位于两条韧性剪切带附近。

n Ergun region,there are mainly three periods of stress fields during Mesozoic Era,i.e.,Indosinian period (T2J1),Tamulangou periods of(J3)and Shang kuli period (K1).In Indosinian period,the orientation of primary stress is NNWSSE,and two large ductile shear zones striking 0～20° were formed,.In Tamulangou period,the orientation of primary stress is NWWSEE,and two groups of conjugate joints striking respectively 60～90° and 320～340° were developed.In Shangkuli period,the orientation of primary stress is NNE-SSW,which made the conjugate joints formed in Tamulangou period remove as fractures,reverse faults,etc.There are many gold,lead and zinc ore deposits(spots)in Ergun.The attitudes of orebodies are identical with the structures formed in Tamulangouperiod and Shangkuli period.Therefore in Mesozoic Era,the master ore forming periods are Tamulangouand Shangkuli periods.The prospectimg for gold deposits in the region should be focused on or beside the two large shear zones.