Chemistry of Tertiary sediments in the surroundings of the Ries impact structure and moldavite formation revisited

0458591 - GLÚ 2017 RIV GB eng J - Článek v odborném periodiku
Žák, Karel - Skála, Roman - Řanda, Zdeněk - Mizera, Jiří - Heissig, K. - Ackerman, Lukáš - Ďurišová, Jana - Jonášová, Šárka - Kameník, Jan - Magna, T.
Chemistry of Tertiary sediments in the surroundings of the Ries impact structure and moldavite formation revisited.
Geochimica et Cosmochimica Acta. Roč. 179, 15 April (2016), s. 287-311. ISSN 0016-7037. E-ISSN 1872-9533
Grant CEP: GA ČR GA13-22351S; GA MŠMT(CZ) LM2011019
Institucionální podpora: RVO:67985831 ; RVO:61389005
Klíčová slova: sediments * Tertiary * tektites * moldavites * Ries impact structure
Kód oboru RIV: DB - Geologie a mineralogie
Impakt faktor: 4.609, rok: 2016

Moldavites, tektites of the Central European strewn field, have been traditionally linked with the Ries impact structure in Germany. They are supposed to be derived mainly from the near-surface sediments of the Upper Freshwater Molasse of Miocene age that probably covered the target area before the impact. Comparison of the chemical composition of moldavites with that of inferred source materials requires recalculation of the composition of sediments to their water-, organic carbon- and carbon dioxide-free residuum. This recalculation reflects the fact that these compounds were lost almost completely from the target materials during their transformation to moldavites. Strong depletions in concentrations of many elements in moldavites relative to the source sediments (e.g., Mo, Cu, Ag, Sb, As, Fe) contrast with enrichments of several elements in moldavites (e.g., Cs, Ba, K, Rb). These discrepancies can be generally solved using two different approaches, either by involvement of a component of specific chemical composition, or by considering elemental fractionation during tektite formation. The proposed conceptual model of moldavite formation combines both approaches and explains moldavite formation in five steps.
Trvalý link: http://hdl.handle.net/11104/0258841