The End Permian Mass Extinction

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Yi and Yan Zheng, 1993)in the layer reveild some interesting results. High Ir values only occurs in the uppermost part of the layers. This means that the layer is close to the PTB. The concentration of Ir was at least an order of magnitude higher than the background values and this is characteristic of most Upper Permian and Lower Triassic boundaries. The scientists go on to say that "the existance of a rich Ir anomaly on a global scale within the K/T boundary layers of both marine and continental facies has been interpreted as highly impressive evidence for an impact origin. Another discovery that may serve as a marker of an event is microspherules. A variety of microsherules have been discovered in the PTB layers of the Meishan section (Xu et al., 1989). The origin of the microspherules could be multiple. They are small circular indentations in the rocks and the most abondent elements are Si or Si-Al. Mircospherules are similar to cosmic dust. Since a large amount of microspherules occurs in a thin layer of PTB layer it can serve as another e...