Glassy spherules containing primary crystallites (clinopyroxene-bearing spherules) and diagenetically altered spherules with relict quench textures have been found in late Eocene and Cretaceous-Tertiary boundary sediments, respectively. These spherules have been referred to as 'microtektites' by some authors. Although the late Eocene spherules and K-T boundary spherules, like microtektites, are believed to have been formed by impact, they are not microtektites, which by definition do not contain primary crystallites. Furthermore, the late Eocene and K-T boundary spherules can be distinguished from microtektites by their more basic composition, the absence of lechatelierite, and an association with iridium anomalies. In order to avoid confusion with microtektites, it is proposed that impact-generated spherules containing primary crystallites be referred to as microkrystites.
Lunar and Planetary Science Conference Proceedings
- Pub Date:
- Earth Surface;
- Hypervelocity Impact;
- Lunar and Planetary Exploration; Miscellaneous