迷坝花岗岩形成时的构造环境判别及^(40)Ar/^(39)Ar年代学研究

迷坝花岗岩位于甘肃东部的康县和陕西略阳交界处的迷坝一带。用Maniar的主元素判别法判定它为造山后花岗岩类(POG型)。角闪石和黑云母的^(40)Ar/^(39)Ar测年结果表明其侵位时代为239～229 Ma,是印支期岩浆活动的产物。在193.8Ma左右的早燕山期受到一次原因不明的热事件影响,导致了岩体中黑云母的氩同位素系统部分开放。

甘肃迷坝矽卡岩型铜矿成矿机理及模式研究

甘肃迷坝铜矿是近些年来在西秦岭发现的比较典型的矽卡岩型铜矿,本文研究了其区域地质背景、矿区地层、构造、岩浆岩及其矿体特征,分析了其成矿要素,总结了迷坝矽卡岩型铜矿成矿机理及模式,以期为西秦岭矽卡岩性的矿床的找矿提供参考。

浅谈康县迷坝钒矿地质特征及找矿标志

迷坝矿区位于南秦岭加里东褶皱带,武都弧型构造东部,舟曲-徽县断裂带以南,迭部-武都-略阳断裂带以北。矿区志留纪白水江群黑色岩系内的含炭硅质板岩为钒矿主要含矿层位,矿带长约700 m,宽约100 m。含矿层整体走向近东西向,南倾,倾角40°～85°。角岩化、硅化与钒矿成矿关系密切,是该区寻找钒矿的重要标志。

Dams and Floods

The possible mitigation of floods by dams and the risk to dams from floods are key problems. The People's Republic of China is now leading world dam construction with great success and efficiency. This paper is devoted to relevant experiences from other countries, with a particular focus on lessons from accidents over the past two centuries and on new solutions. Accidents from floods are analyzed according to the dam's height, storage, dam material, and spillway data. Most of the huge accidents that have been reported occurred for embankments storing over 10 hm3. New solutions appear promising for both dam safety and flood mitigation.