Correlation potential of the Upper Jurassic (lower Kimmeridgian) Platynota Chronozone deposits in northeastern Spain

Abstract

Ammonite biostratigraphy and its correlation potential are evaluated for the lower Kimmeridgian, Platynota Chronozone, in the eastern Iberian Range, E–NE Spain. The presence of the Orthosphinctes, Ardescia desmoides and Schneidia guilherandense subzones has been confirmed. Four formal ammonite "intra-subzone biodivisions" (i.e. so-called horizons or biohorizons) are recognised, one of them defined for the first time – the Olorizia olorizi "intra-subzone biodivision". Based on the discovery of new ammonite assemblages, the biostratigraphic scheme proposed at the biozone level is considered to have strong correlation potential for successions deposited in Tethyan epicontinental and oceanic fringe environments. The potential for correlation at the intra-zone level is higher with respect to epicontinental than oceanic fringe deposits, but precise correlation at the subzone and "intra-subzone biodivision" levels between the eastern Iberian Range and SE France remains difficult. An updated subdivision of the Sutneria platynota Biozone is interpreted for oceanic fringe sections. Additionally, the ammonite genus Olorizia Moliner is erected and briefly discussed.