论文部分内容阅读
遍布全球的Ｋ／Ｔ界线粘土层不仅存在着铱的丰度异常，其它铂族元素的含量也异常高，并且基本上保持着类似与地外物质中的丰度分布模式。实验表明，在粘土层中铂族元素主要呈可交换离子相和难溶金属相的形式存在，而在硫化物和硅酸盐相中的含量却很低。这与铂族元素来源于地外物体撞击的成因解释是一致的。此外，在铂族元素异常层位上普遍有超高温矿物变种（富镁铁尖晶石）、冲击变质矿物和玻璃陨石与其伴生。这些现象为Ｋ／Ｔ界线地外撞击事件的确定提供了无可争议的地质证据。
The global K / T boundary clay layer not only has the abundance anomaly of iridium, but also the content of other platinum group elements is abnormally high, and basically maintains the abundance distribution pattern similar to that of the extra-terrestrial material. Experiments show that in the clay layer, the platinum group elements are mainly in the form of exchangeable ion phase and insoluble metal phase, while the content of sulfide and silicate phase is very low. This is consistent with the explanation of the origin of platinum group elements originating from the impact of extraterrestrial objects. In addition, there are ubiquitous ultra-high temperature mineral species (Mg-rich spinel), impact metamorphic minerals and glass meteorites in the anomalous layer of platinum group elements. These phenomena provide indisputable geological evidence for the determination of K / T boundary external impact.