| 苏州西山震裂锥:太湖冲击坑又一新证据 |
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| 引用本文： | 王鹤年,钱汉东,陈旸,周丽娅.苏州西山震裂锥:太湖冲击坑又一新证据[J].高校地质学报,2019,25(1):58. |
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| 作者姓名： | 王鹤年 钱汉东 陈旸 周丽娅 |
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| 作者单位： | 南京大学地球科学与工程学院,南京210023;南京大学内生金属矿床成矿机制研究国家重点实验室,南京210023;南京大学地球科学与工程学院,南京,210023;南京大学地理与海洋科学学院,南京,210023 |
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| 基金项目： | 国家重点实验室自主研究项目;国家重点实验室自主研究项目;国家自然科学基金 |
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| 摘 要： | 震裂锥已被公认为陨石冲击地球表面遗留的标志。研究及统计资料表明，震裂锥与陨石冲击形成的中、大型冲击坑
有关。太湖西山震裂锥呈圆锥形，锥体表面有自锥顶向下辐射的锥纹，锥纹具有分叉的特征，这些特征与震裂锥的国际公
认的定义和标准相符。此外，西山震裂锥还具有其特有的其他特征：碎裂岩化显著；气化-熔融现象发育；锥体表面具网
状构造及波纹状、蜂窝状等多种气印。岩相学研究显示，震裂锥及含锥岩石中冲击变质现象明显，微页理（PDFs）、微裂
隙（PFs） 以及靶岩熔融现象发育。以上这些冲击变质的标志，可证明西山震裂锥是冲击成因，而非地表水风化淋溶石灰岩
的喀斯特或风蚀成因的凤稜石。西山震裂锥的发现、太湖湖底冲击击变角砾岩“太湖石”的确定，为太湖冲击坑的研究增
添了新的诊断性证据；加上早期研究确定的、冲击回落至太湖湖底淤泥层中的冲击溅射物，这些众多证据为确定“太湖冲
击坑”或“太湖冲击事件”展示了美好前景。但是，要确定太湖冲击坑的具体位置、大小及构造模式等，尚需更多的深入
研究。
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| 关 键 词： | 太湖 震裂锥 冲击坑 冲击角砾岩 熔融—气化作用 |
Shatter Cones in Xishan,Suzhou: A New Evidence for Taihu Lake Impact Crater |
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| WANGHenian,QIAN Handong,CHENYang,ZHOULiya.Shatter Cones in Xishan,Suzhou: A New Evidence for Taihu Lake Impact Crater[J].Geological Journal of China Universities,2019,25(1):58. |
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| Authors: | WANGHenian QIAN Handong CHENYang ZHOULiya |
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| Abstract: | The shatter cones have been recognized as a sign of meteorite impact on the earth's surface. Research and statistical data
show that shatter cones are related to medium-or larger-scale impact craters. The shatter cones found in Xishan, Suzhou provides a
diagnostic evidence for the existence of impact crater happened in Taihu Lake. The shatter cones are characterized by the conical shapes
and coved with conical striations radiating downward from the top of the cones. The striation has been shown as the feature of
bifurcation. The evidences are consistent with the international definition and standard for the shatter cone. In addition, special
characteristics are also found in shatter cones in Xishan: remarkable cataclasis and the obvious melt-gasification phenomenon. On
surface of cones, there are mesh-structure and the ripples-like, honeycomb-like gas imprint developed. Results of petrographic study
show that shatter cones and cone-contained target rocks have visible impact metamorphism. Planar Deformation Features PDFs], Planar
Features PFs] and target rock melting indicate the impact metamorphism happened. All of these show that shatter cones in Xishan are
distinctly different from cone-sharp karst limestone formed by the surface water dissolution or ventifacts formed by eolian erosive action.
The discovery of Xishan shatter cones and the breccias“Taihu stone” occurring at the bottom of the Taihu Lake has provided the new
diagnostic evidence for the Taihu impact crater. There are also existed impact ejecta identified in earlier studies which fallen back into
the silt layers under the Taihu Lake. Numerous evidences show a beautiful prospect for the determination of “Taihu impact crater” or
“Taihu impact event”. However, there is still much work to be done to determine the detailed locations, size and structural model of the
impact crater in Taihu Lake. |
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| Keywords: | Taihu Lake shatter cone impact crater impact breccias melt-gasification |
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