Lechatelierite-Bearing Microspherules from Semicoke Hill (Kiviõli, Estonia): Contribution to the Contamination Problem of Natural Microtektites

F. Marini ； A. Raukas

《Oil Shale》 26卷3期 (2009/09) Pp. 415-423

並列摘要

During the course of the last hundred years, microscopic magnetite and glassy spherules of different genesis (extraterrestrial, volcanic, industrial, biogenic, diagenic, explosive, etc.) have often been found in various geological formations. Alongside classical geological methods, research into extraterrestrial and explosive spherules can provide valuable information and facilitates stratigraphical correlations over large areas. Several authors have recently stressed that studies on cosmic-and impact-related microspherules may seriously be hampered by outcrop-and laboratory contamination. Fly-ash particles and steel slags resembling iron-rich cosmic spheres are the most frequently invoked industrial contaminants. In contrast, little attention has been paid to glassy spherules of industrial origin that might resemble microtektites. Our finding of lechatelierite inclusions in obvious industrial provenance might cast serious doubts of the validity of the classical «Lechatelierite Criterion» as a test for impact glasses.