铂族元素矿床研究的某些新进展及其对于四川找铂的启示

Some Advances in the Prospecting and Study of PGE Deposits and their Inspiration to the Exploration of PGE Deposits in Sichuan,China

近年来由于市场需要 ,国内外都开始新一轮的铂族元素矿床找矿工作并取得了新进展。这些进展突出地表现为在世界各地都有新的矿床、矿点发现 ,其中特提斯—喜马拉雅成矿带有可能成为一条新的铂族元素成矿带。在成矿理论方面 ,铂族元素的热液成矿机制和铂族元素在相对低温条件下通过热液作用的活化转移、重新成矿机制受到普遍关注。我国西南部地区的铂族元素矿床具有点多面广、类型多、时代多的特点 ,尤其是后期构造—热事件对于前期含矿构造层的影响非常明显 ,这一方面可能破坏了原有的含矿岩体使之支离破碎 ,但也因此可能形成富矿体。以PGE找铂的地球化学方法在使用时应考虑到具体的地质情况 ,高异常不见得有矿 ,低异常也不见得无矿。

Due to the large market demand,a lot of exploration activities for platinum-group elements deposits around the world resulted in numerous new discoveries during the past decade.Even new localities distributed all over the world,it is more attractive that there are some important new discoveries in the Tethys-Himalayan metallogenic belt,suggesting that it is possible for this belt to become a new producer of PGE in the future.On the other side,the traditional theories of PGE metallogeny are under challenge,because more and more evidences showing that the remobilization of PGE can occur under an even low temperature condition.In the southwestern China,there are numerous occurrences of PGE,which belong to different types and formed in different ages,suggesting a good future for explorationg new PGE deposits.However,all of these PGE deposits or occurrences have been subjected to poly-stage of tectonism,such as heating-uplifting,deep faulting or large scale thrusting in shear zone,resulted in the remobilization of plinium-group elements.Thus,some of the original orebody or ore zone might have been dismembered,but more informationg might be given by the process of tectonic-reactivity.The geochemical method of using PGE anomaly for exploration is generally useful,but should concordant with its geological setting and the mechanism of PGE mineralization,because the high abnormal of PGE content do not mean a PGE deposit(especially in the mantle plume originated large igneous province)while the low abnormal of PGE content do not mean no mineralization.