66th Annual Meteoritical Society Meeting (2003) 5201.pdf

NO EVIDENCE OF IMPACT ORIGIN OF THE AMOENEBURG-BASIN (HESSEN, GERMANY). M. Harting, G. Istrate, S. Semertzidis-Griebel, M. Meudt, V. Zibat, D. Stüben.

Lot of material has been found with remarkably but only morphological identity to real tektites as well as some pieces assumed as melted rocks, shatter cones and (impact-) glasses in the Amoeneburg-Basin (Hessen, Germany) by amateurs. However, our recent scientific investigations show that these material from the Amoeneburg-Basin is just terrestrial material. Assumed tektites could be identified as diagenetic concretion of Buntsandstein material. Assumed shatter cones could not be identified as real shatter cones according to definition (Gibson & Spray, 1997), more likely they seem to be surface features like striae or tectonical induced harnisch surfaces. The assumed melted rocks are silica- concretions of the upcoming formations. Glasses found inside the basin are clearly volcanic material (obsidian) or of industrial affinity and show no similarity to tektite glasses. Assumed spherule rich deposits are red chert silica concretions with secondary, spherical crystallization. Pigmentation of argillaceous or silica rich sediment or gel is related to the mineralogy of iron-bearing constituents. The red-purplish pigmentation is produced by hematite; this may be of primary origin or formed during diagenesis in an oxidizing environment, by direct precipitation from a gel, or by dehydration of iron hydroxides. There is no evidence for impact origin according to real impact induced spherules (Harting et al., 2002; Schulte et al., 2002) for these material. Field examinations inside the basin were also inconclusive, only common country rocks as well as their tectonical features could be observed. High-pressure minerals like coesite/stishovit cold not be determined. Few other rock fragments found inside the basin could not be repatriated to the Amoeneburg- Basin. According to Upheaval Dome structure, Utah (Koeberl et al., 1999) the Amoeneburg-Basin shows just and only sparse morphological affinity to real impact sites. Koeberl, C., Plescia, J.B., Hayward, C.L. & Reimold, W.U. (1999): A petrographic and geochemical study of quartzose nodules, country rocks, and dike rocks from the Upheaval Dome structure, Utah. – Meteoritics Planet. Sci. 34, 861-868. Harting, M., Rickers, K., Kramar, U., Simon, R., Staub, S. & Schulte, P. (2002): Multielemental geochemical investigations by SRXRF microprobe studies on tectite material: Evidence from the NE-Mexican Cretaceous/Tertiary record. – Eos Trans. AGU, 83 (47), Fall Meet. Suppl. Abstract P22B-0403, 2002. Schulte, P., Stinnesbeck, W., Kontny, A., Stüben, D., Kramar, U. & Harting, M. (2002): Multiple (immiscible) melt phases of mafic composition in Chicxulub impact ejecta from northeastern Mexico: New constraints on target lithologies. – Eos Trans. AGU, 83 (47), Fall Meet. Suppl. Abstract OS22C-0293, 2002.