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.
