Geochronology of Hydrothermal Systems Related to Ore Mineralization

9526673霍尔这个项目将最新改进的40Ar/39Ar测年技术应用于大型热液系统的测年问题。最近对40Ar/39Ar方法的改进证明了这种技术甚至可以处理最细的颗粒材料的潜力。该项目将集中在五个研究区域：a)巴拿马的Cerro Colorado斑岩铜矿床；b)具有原有Rb-Sr年龄信息的密西西比河谷型(MVT)矿床；c)内华达州沉积物赋存的微米金矿床(双溪)；d)西班牙的Almaden汞地区；e)纳米比亚的TSumeb-Kombat烟囱矿床。所有五个地点的样本都已收集完毕。塞罗科罗拉多矿床与粗粒矿物有关，已用K-Ar定年，这将为细粒蚀变产物的年龄提供很好的测试。MVT矿床具有已有的高质量Rb-Sr年龄，从而为该系统提供了进一步的测试。剩下的三个地点已经安排了现有的年龄，但对热液活动的时间几乎没有达成共识。正是有了这些网站，该项目才能提供最多的新信息。

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.