Geochronology of Hydrothermal Systems Related to Ore Mineralization

9526673 Hall本项目将最新完善的40 Ar/39 Ar定年技术应用于大规模热液系统的定年问题。 40 Ar/39 Ar方法的最新改进已经证明了这种技术处理甚至是最细晶粒材料的潜力。 该项目将集中于五个研究领域：a）巴拿马Cerro科罗拉多斑岩铜矿存款; B）具有预先存在的Rb-Sr年龄信息的密西西比河谷型矿床; c）内华达州（Twin Creeks）沉积物中的微米金矿床; d）西班牙Almaden汞区; e）纳米比亚Tsumeb-Kombat烟囱矿床。 已收集了所有五个地点的样本。 Cerro科罗拉多存款与粗粒矿物已经使用K-Ar定年，这将提供一个很好的测试的年龄来自细粒蚀变产物。 MVT矿床已经获得了高质量的Rb-Sr年龄，从而提供了对该系统的进一步测试。 剩下的三个地点有现有的年龄安排，对于热液活动的时间很少有共识。 正是这些网站，该项目应该提供最大数量的新信息。

9526673 Hall This project applies newly refined 40Ar/39Ar dating techniques to the problem of dating large scale hydrothermal systems. Recent improvements in the 40Ar/39Ar method have demonstrated the potential for this technique to handle even the finest-grained material. This project will concentrate on five study areas: a) the Cerro Colorado porphyry copper deposit, Panama; b) Mississippi Valley-type (MVT) deposits with pre-existing Rb-Sr age information; c) sediment-hosted micron gold deposits, Nevada (Twin Creeks); d) the Almaden mercury district, Spain; e) the Tsumeb-Kombat chimney deposits, Namibia. Samples for all five sites have been collected. The Cerro Colorado deposit is associated with coarse-grained minerals which have already been dated using K-Ar, and this will provide a good test for the ages derived from fine-grained alteration products. The MVT deposits have high quality Rb-Sr ages already available, thus providing a further test of the system. The remaining three sites have arrange of existing ages with very little consensus as to the timing of the hydrothermal activity. It is with these sites that the project should provide the greatest amount of new information.