THE HISTORY OF TEKTITES

Abstract

This account covers the history of tektites, from prehistoric times, through the descriptions by the Chinese in medieval times, their discovery and description in the Austro-Hungarian Empire in the 18th century, Charles Darwin's encounter with a flanged button australite at what is now Albany, Western Australia, in the early 19th century, and the descriptions by Lacroix and others of further discoveries in Indo-China, the Ivory Coast and the USA, in the first half of the 20th century. F.E. Suess and R.H. Walcott first suggested a meteoritic provenance about 1900, and L.J. Spencer suggested ejection from terrestrial impact sites. Up to the 1950s, sophisticated research techniques were not available and speculation ruled, with many highly imaginitive and fanciful hypotheses emerging. As the Apollo landing approached, many new sophisticated research methods were developed and research proliferated. Evidence for terrestrial origin accumulated at this time, although lunar origin remained popular, and it was confirmed by rejection of lunar provenance following the Apollo and Luna recovery missions. The favoured mode of origin became ejection from a minority of large-scale impact sites on the Earth, and the relationship between the Ries impact structure and moldavites, and between Bosumtwi Crater and Ivory Coast tektites, was firmly established. Then in the 1990s the Chesapeake Bay structure was discovered, the source of the North American tektites? Wind-tunnel experiments by D.R. Chapman showed that flanged-button australites were produced by ablation on descending through the atmosphere. Prolific researches, led by B.P. Glass, on deep-sea cores revealed the existence of microtektites, thus extending three of the strewn fields to large areas covered by sea. Kindred occurrences at Zhamanshin and Popigai in the USSR, in a Pliocene structure beneath the south Pacific Ocean, at the Cretacetus-Tertiary (K/ T) boundary in Haiti and Mexico, and within late Devonian sediments in Belgium and China are briefly described, as well as natural glasses in Libya and Tasmania, of obscure origin. There remain a number of unsolved questions - among them the source of the huge Australasian Strewn Field, the enigma of the manner of dispersal of large, irregular Muong Nong-type tektites, the relationship of microtektites to the larger tektites found on land, and the relationship of all tektites to the geology of the likely target area of the source impact and processes of jetting from impact sites. © The Geological Society of London 2006.