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

本论文是由李志刚博士提出的“中国冲击结构的寻找与研究”的建议。美国大学研究协会月球与行星研究所的V.L. Sharpton和Kevin Burke以及徐道教授。易和何勇。中华人民共和国国家地震局地质研究所“年”项目由美国国家科学基金会资助。全世界公认的大约120个撞击结构记录了小行星和彗星撞击地球的性质和影响。虽然这些构造很容易被随后的地质过程所掩盖，但北美、欧洲和澳大利亚的密集空间分布清楚地说明了努力寻找这些构造的有效性，以及在剩余的大陆地区开展此类努力的潜力。对于中国广袤的陆地，陨石坑产生的计算表明，直径(D)大于20公里的陨石坑应该有10.15个，但没有一个得到证实。美国研究人员利用中国的轨道图像记录了41个圆形结构（3公里至70公里），然而，除了少数外，似乎都是内生的。最有潜力的构造包括多伦、上河湾、伦敦社、内洞和太湖。迄今为止，没有明确的岩石学证据证明这些特征中的任何一个是撞击起源的。中国的陨石坑研究将通过(1)对中国上述5个构造进行广泛的实地研究，(2)对北美8个已知的撞击构造进行实地研究，为中国人提供对撞击构造的了解。这项工作包括构造作图、岩石学分析和同位素测年的样品收集，短期内将有助于更清楚地了解目标中国构造的起源，并在短期内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.