关键词: 击变岩, 陨石坑, 三山岛, 太湖

Abstract: In Sanshan islet of Taihu lake, several peculiar stones, identified to be well-developed shock metamorphic rocks, were first found by the authors. It is suggested that they were formed by the impact of an ancient giant meteorite on the Devonian quartzitic sandstones of the Wutong Lorma-tion. Macroscopically, they do show some distinct disintegration partings. And microscopically, they are characterized by the development of bending of quartz grains, the presence of multiple sees of planur features, mechanical twining quartz crystals, the existence of diaplectic glasses, 1e-chatelerites and the radiating fractures in quartz grains which were thought to be caused by the process of phase transformation from the precursor mineral coesite to ordinary quartz. All these phenomena might attribute to a peculiar geologic event caused a sudden impact of a rne-teorite onto the ground surface. This discovery might cast a new light on the origin of Taihu lake, and it might be regarded as an important breakthrough in such a research field.

Key words: Shock metamorphic rocks, Impact crater, Shanshan islet, Taihu lake