9316561 Wasson This proposal requests funds to permit Dr. John T. Wasson, Institute of Geophysics and Planetary Physics, University of California, Los Angeles, to pursue with Professor Kaset Pitakpaivan, Retired Director, Geological Survey Division, Department of Mineral Resources, Thailand, for a period of 18 months, a program of research to locate and identify craters in northeast Thailand associated with the formation of the Australasian tektites. Field work will be conducted by collaborating U.S. and Thai teams of about five members each. Theory holds that tektites, glasses with high silicon dioxide (60-80%) and high aluminum oxide (10-15-%) contents, are produced by the melting of a well-mixed continental sediment such as shale or soil during the impact of an asteroid or comet with the Earth. Small tektites, usually weighing less than 300 g and in the shape of disks, dumbbells, and teardrops, are believed to have been formed by the solidification of a liquid while spinning in the atmosphere. Larger layered tektites are believed to have been formed on the ground from puddles of silicate melt. Promising research sites will be identified from remote sensing data provided by the Thai collaborators. Rock samples returned from the field will be examined for shocked quartz by optical microscopy, nuclear magnetic resonance, and by other techniques to search for evidence of shock effects. Confirmation of the impact origin of tektites requires the identification of the crater or craters, but none has been found. While most researchers are of the opinion that the tektites were produced in a single crater with a diameter of about 10 km or more, the PI has proposed that additional smaller craters are required to account for the layered tektites which are found across a 1,200 km distance from Hainan Island through Cambodia to Thailand. The highest density of Australasian tektites is found in the southeast corner of northeast Thailand. The research problem is of great interest to geologists, and the present project may do much to resolve the uncertainty in this field regarding the formation of these tektites. The PI and his collaborators are highly respected researchers in the field of this proposal. This project is relevant to the objectives of the East Asia and Pacific Program which seeks to increase the level of cooperation between U.S. scientists and engineers and their counterparts in the Asia-Pacific region through the exchange of scientific information, ideas, skills, and techniques and through collaboration on problems of mutual benefit. ***
