NEW METHOD FOR THE STUDY OF AIRBORNE PARTICLES BASED ON TREE-RESIN TRAPPING AND ANALYTICAL ELECTRON-MICROSCOPY

This paper describes a new method for the study of datable airborne particles, of both terrestrial and extraterrestrial origin, and presents preliminary results of an application which casts light on the famous Siberia explosion of the beginning of the century. A dramatic, airborne explosion occurred on 30 June 1908 in Tunguska, Siberia, causing a fire in an area of about 2000 km2, while in a larger region trees were felled in radial directions. No craters were found at the epicentre of the damaged area. A large amount of literature is available on the subject and several suggestions were made on the cause of the catastrophe, the more probable, comet or asteroid collisions, besides other less plausible speculations. The interest is diffused among different scientific disciplines such as astrophysics and cosmology, nuclear physics, earth and environmental sciences and even politics. Conventional chemical analyses of material picked up on the scene have been inconclusive in clarifying the cause of the event. This paper presents preliminary results obtained by a new method based on analytical electron microscopy of micro-sized airborne particles trapped in tree resin at the time of the explosion and preserved during the following years. The results clearly show that this approach can yield significant, historically reliable information. The method can be applied also in other fields, such as for monitoring and studying volcanic emissions and for investigating cosmic dusts which arrived on the earth before heavy modern pollution took place and different kinds of fall-outs.