SECONDARY MELT CHARACTERISTICS: EVIDENCE SUPPORTING AN EXTRATERRESTRIAL PROVENANCE FOR WESTWATER, UTAH, MICROSPHERULES

Microspherules (MS) ranging in size from 1µm to 425µm were first discovered at Westwater, Utah, in Jan. 2000. Both magnetic metallic crystalline and non-magnetic cryptocrystalline glass MS were separated from sediments excavated from what appears to be the bottom of a late Pleistocene or early Holocene ice dam lake situated along the banks of the Colorado River about two and one-half miles west of the Colorado-Utah state line.

A scanning electron microscope and energy dispersive spectrometry were used to compare the Westwater MS with known terrestrial (T) and extraterrestrial (ET) particles. Though basic chemistry of T and ET particles is difficult to use as identifying criterion, this chemistry in combination with specific MS morphology may be used (in certain circumstances) to identify the cosmic origin for some MS.

Upon entry into the earth's atmosphere particles greater than ± 600µm (?) tend to vaporize, whereas particles less than 200µm to ± 600µm range will experience heating sufficient to cause partial melting and associated morphological alterations including annealed tails, ablation rings, melt material tracks, melt scour grooves, and migration of melt material.