构造因素分析是成矿过程分析的基本要素之一.本文通过对各古构造层中发育的共轭剪节理和褶皱测量统计,恢复了本区白垩纪以来的各期古构造应力场,发现各期古构造应力场的中间主应力轴均为近水平状态,其中建德期最大主压应力方向为NW向,衢江期最大主压应力方向为NNE向,始新世-渐新世期最大主压应力方向为近EW向.指出本区球川-萧山断裂等NE向区域大断裂构造开启的期次,决定了成矿期次,开启的时间决定了铀矿形成的年龄,其开启时序明显受古构造应力场发展演化控制.建德期晚期,随着NW向挤压应力场转为应力松弛状态,区域大断裂处于开启状态,火山喷发期后的深部含矿流体沿区域大断裂向上运移,形成了本区早期铀成矿(125～115 Ma),衢江期NNE向挤压构造应力场使本区区域大断裂再次开启,带来了深部成矿流体,形成了第二期铀成矿(90～70.2 Ma),两期铀成矿叠加最终形成了本区的铀矿化定位.%Analysis of tectonic factors is one of the bases for metallogenic research.Based on measurement of conjugate shear joints and folds developed in each paleotectonic layer,the paleotectonic stress fields since Cretaceous in each period have been recovered.It is found that the intermediate principal stress axes of these paleotectonic stress fields are all nearly horizontal.The direction of the maximum principal stress is NW trending in the Jiande age,NNE trending in the Qujiang age and nearly EW trending from Eocene to Oligocene.It is showed that the period and stage of uranium mineralization are determined by the period and stage of extension of the NE trending regional large faults,such as the Qiuchuan-Xiaoshan fault,whose extensional subsequence is controlled significantly by the evolution of paleotectonic stress field.In the late Jiande age,with the NW trending compressional stress field converted to relaxed state,regional faults were changed from the original thrust faults to tensional faults,and the early stage uranium mineralization (125-115 Ma) was related to migration of ore-bearing fluid along the deep fault subsequent to volcanic eruption.In the Qujiang age,the deep faults were extended again due to NNE trending compressional tectonic stress field,which supplied channel ways for the late stage uranium mineralization (90-70.2 Ma).Eventually,the uranium mineralization in this area is result of two stages of superimposition.
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