The chemical variation of moldavite tektites: Simple mixing of terrestrial sediments

Abstract

Abstract-To test different hypotheses of moldavite formation, a major and trace-element study of 25 moldavite tektites and Sm-Nd isotope measurement of three moldavite tektites was completed. The samples were selected from the classical substrewnfields and the newly described locations in Lusatia (Saxony, Germany). Samples with unusual bulk composition were also included. The results c o n f m earlier studies that the variation in the chemical composition can be explained by single impact and through incomplete mixing of at least three lithographical components dominated by one of the three minerals or mineral groups: dolomite, clay minerals and quartz. An additional endmember, possibly a rare Earth's mantle component, containing high Co, Cr and Ni concentrations is also needed to explain the observed variations in compatible elements of some tektites. Volatile element abundances are low but not necessarily the result of selective volatilization.

A laboratory model of splash‐form tektites

“…Applying the viscosity calculation techniques of Bottinga and Weill (1972) and Shaw (1972) to various tektite compositions (Glass 1972;Frey 1977;Meisel et al 1997;Albin et al 2000) suggests that, at their liquidus temperatures, tektites vary in viscosity from 10 2 to 10 7 Pa s. These results are in agreement with the calculations of Klein et al (1980), who found tektite viscosities in the range 10 2 to 10 13 Pa s over the temperature range of 700 to 1400°C. To investigate the influence of temperature on viscosity, we consider experimental and analytical results for magmatic liquids: Dingwell et al (2000) found that granitic melts, some of which are reasonable analogues for tektites, vary in viscosity from 10 10 to 10 12 Pa s at 1000°C and from 1 to 10 3 Pa s at 2000°C.…”

Chemistry, small-scale inhomogeneity, and formation of moldavites as condensates from sands vaporized by the Ries impact

“…observed two SiO 2 enriched and two SiO 2 depleted zones on a 250 m long traverse in a moldavite from Locenice, Bohemia. Rost (1966) and Meisel et al (1997) described Muong-Nongtype moldavites from Bohemia. Bouška and Ulrych (1984) observed nine "two-coloured" moldavites from Southern Bohemia, in which brownish zones were poorer in SiO 2 than the surrounding glass.…”

The most distal moldavite findings from Lower Silesia, Poland

“…The Ries crater was produced by the impact of an asteroid that was probably 1.5 km in diameter (STÖFFLER et al, 2002). European tektites originated from the melting of the uppermost sedimentary target rocks that belong to the Upper Freshwater Molasse, which overlies the Swabian-Franconian Alb plateau (MEISEL et al, 1997;TRNKA and HOUZAR, 2002;ŘANDA et al, 2008;MAGNA et al, 2011; BRACHANIEC et al, 2014bBRACHANIEC et al, , 2015BRACHANIEC et al, , 2016, and this study). B. and C. General view of the Gozdnica Formation in the western part of the Nowa Wieś Kącka sandpit.…”