Tektites
Tektites
- Christian KoeberlChristian KoeberlUniversity of Vienna
Summary
Tektites are a rare type of impact glass; they are found in only four distinct and geographically extended strewn fields, ranging from 0.8 to 35 million years in age. For three of these four strewn fields, the source crater is known. Microtektites from three of the four fields are also known from deep-sea cores, in addition to normal, centimeter-sized specimens; their distribution defines the extent of the strewn fields. Tektite-like glasses have more recently been found in a few other locations, but they show limited distribution, or few specimens have been recovered, or their sources and origins are not well understood, or a combination of these circumstances may be the case. Tektites differ from “normal” impact glasses in that they were derived from the very surface of the target area (as is indicated by their high content of the cosmogenic radioisotope 10Be) and may have formed and been ejected before the main crater excavation phase even began. They have very minor meteoritic components, as indicated in, for example, Os isotopic studies. As most tektites are homogeneous glass, they must have experienced extremely high formation temperatures. Twenty-first-century work has shown that Zn, Cu, Cd, and Sn are isotopically fractionated by volatilization in tektites. The study of unconventional stable isotopes provides interesting clues regarding the formation, differentiation, and deposition of tektites. Tektites are clearly an interesting and unusual subtype of impact glasses.
Subjects
- Planetary Surfaces