U.S.-China Cooperative Research: Search for and Study of Impact Structures in China

大学研究会月球与行星研究所的V.L.Sharpton博士和Kevin Burke博士与中华人民共和国国家地震局地质研究所的徐道毅教授和贺永年共同提出的《中国撞击构造的寻找与研究》是由国家自然科学基金资助的。全世界公认的大约120个撞击结构记录了小行星和彗星与地球碰撞的性质和影响。虽然这些构造很容易被随后的地质作用所掩盖，但北美、欧洲和澳大利亚的空间分布却清楚地表明了密集努力寻找这些构造的用处，以及在剩余的大陆地区发起这种努力的潜力。对于辽阔的中国大陆，陨石坑产量计算表明，应该存在10，15个直径(D)大于20公里的陨石坑，但没有一个得到证实。美国研究人员使用中国的轨道图像记录了41个环形结构(3公里×70公里)，然而，除了少数似乎是内生的。最有前景的建筑包括多伦、上河湾、龙斗社、内东和太湖。到目前为止，还没有明确的岩石学证据表明这些特征中的任何一个都是撞击起源。对中国撞击坑的研究将通过(1)对中国的上述5个构造进行广泛的野外考察，以及(2)对北美8个公认的撞击构造进行实地考察，从而使中国人对撞击结构有更深入的了解。这项工作包括构造填图、岩相学分析和同位素测年样品采集，短期内将提供对目标中国构造来源的更清楚了解，短期内将为继续在中国寻找撞击构造奠定基础。

This proposal on "Search for and Study of Impact Structures in China" between Drs. V.L. Sharpton and Kevin Burke of the Lunar and Planetary Institute of the Universities Research Association Inc. and Professor XU Dao.Yi and HE Yong.Nian of the Institute of Geology, State Seismological Bureau, People's Republic of China is sponsored by NSF. Approximately 120 impact structures recognized worldwide document the nature and effects of asteroidal and cometary collisions with Earth. While such structures are obscured readily by subsequent geological processes, the clustered spatial distribution within North American, Europe, and Australia clearly illustrates the usefulness of intensive efforts to search for these structures and the potential for initiating such efforts within the remaining continental regions. For vast landmass of China, crater production calculations suggest 10.15 craters with diameters (D) greater than 20 km should be present but none have been substantiated. The American researchers have documented 41 circular structures (3 km D 70 km) using orbital imagery of China, all but a few, however, appear to be endogenic. The most promising structures include Duolun, Shanghewan, Londoushe, Neidong and Tai Hu Lake. To date, clear petrographic evidence of an impact origin for any of these features has not been demonstrated. This study of impact craters in China will be achieved by (1) extensive field study of the 5 aforementioned structures in China, and (2) field study of 8 recognized impact structures in North America, to provide the Chinese with an understanding of impact structures. This effort, involving structural mapping and sample collection for petrographic analysis and isotopic dating, will provide, in the short term, a clearer understanding of the origin of the targeted Chinese structures, and in the short term, the basis for continuing effort to search for impact structures in China.