HORNUNG, T. (2002)

Orthosphinctes (Pseudorthosphinctes) cf. suevicus SIEMIRADZKI 1898 - ein ungewöhnlicher Ammonitenfund aus
der nördlichen Frankenalb

Orthosphinctes (Pseudorthosphinctes) cf. suevicus SIEMIRADZKI 1898 - an uncommon ammonite from the Northern Franconian Switzerland



The topmost galar ammonite subzone (uppermost Oxfordian) provided one bodily preserved ammonite in an uncommon stage of conservation: a lot of idiomorphic pyrite crystalls were grown in the transition zone between phragmocon and living chamber. The overgrowing of one globular to cubically crystall on the ammonite phragmocon is very frequent within the rich ammonite faunule of the Oxfordian and Kimmeridgian. This specimen, coated additionally by an green-coloured glaukonite, shows at least around 30 pyrite crystalls evidenced by X-ray analysis pointing to locally reduced microsetting within an aerobic environment.


published in: Geol. Bl. NO-Bayern 52, 1-4: 63-68, Erlangen