Nickel-rich Tektites from Australia

Abstract

DURING the course of an extensive investigation of the geochemistry of australites by me and others^1,2 a total of 43 determinations of major and trace elements have been made. These results have served to establish the abundances of the chemical elements in australites, their range in composition, the chemical composition of their parent material, and the geochemical environment at their place of origin². A primary purpose of the work has been to determine the abundance of elements critical for theories of tektite origin. Because tektites are commonly believed to originate during impact of a meteorite, asteroid or comet on another body³, an investigation was made of the concentration of elements such as nickel, which, by analogy with terrestrial impact glasses, could provide evidence of the event. With two exceptions, which are the subject of this communication, the nickel content of australites averages 30 p.p.m., with a range in values of 23–35 p.p.m. (Table 1). The average iron–nickel ratio is 1,180, the nickel–cobalt ratio is 2.0 and the chromium–nickel ratio averages 2.5. These values are very similar to those encountered in crustal rocks (Table 1, columns 5 and 6), and the australite data in general provide little evidence for any extra-terrestrial component.