滇西南发现石英面状变形构造

PLANAR DEFORMATION FEATURES OF QUARTZ DISCOVERED NEAR LANCANGJIANG DEFORMATION ZONE IN SW YUNNAN, CHINA

采自云南省西南部澜沧江中游临景大桥以东约2km、勐戛河下游北岸的岩石样品的薄片中发现了非常清晰的石英面状变形构造(PDFs)。根据伦敦大学矿物岩石与冰物理实验室费氏台(universalstage)测量分析结果、样品所在地地层时代特征和航卫遥感图像特征的综合分析,认为该PDFs属陨击成因,其陨击事件大约发生在白垩/第三纪边界(距今65Ma),所引起的冲击变质作用已接近最高级阶段的高压二氧化硅相,样品位置接近陨击坑的中心。

The thin sections of rock sample from the north bank of lower course of the Mengga River in western Jinggu County, Yunnan Province, southwestern China, showed a sharply clear planar deformation features （PDFs for short）. Based on analysis by synthesis of remote sensing images, strata from which the rocks were sampled, and the results of universal stage measurements made at the Laboratory of Mineral Rock and Ice Physics, Department of Earth ＆ Planetary Sciences, University College London, the PDFs could be considered as causing by meteorite impact. The impact event might take place at the Cretaceous/Tertiary boundary （65 Ma ago）. The shock metamorphism caused by the impact event might reach near the highest phase of higher P silica phases, and the sampling location be near the center of meteorite-impact crater. It is the first time to discover the most typical meteorite-impact-caused PDFs in China.