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Rettenbacher Quarry carbonate sequence in the Northern Calcareous Alps represents highly dynamic pelagic carbonate sedimentation in the lower slope environment. The section spans from upper Tithonian Crassicollaria colomi Subzone to middle Berriasian Calpionella elliptica Subzone. Radiolarian samples belong to Pseudodictyomitra carpatica Zone. Considerable redeposition of calpionellids, organic walled dinoflagellate cysts, calcareous nannofossils and foraminifera in the allodapic layers, as well as extensive normal polarity remagnetisation event with substantial clockwise rotation is documented. Quantitative predominance of genera Watznaueria and Cyclagelosphaera indicate strong nannofossil modification during diagenesis. The almost straight trend in the δ13C with some slight carbon-isotope perturbations is recorded at Rettenbacher. Three significant and stratigraphically important negative excursions of the δ13C carb values were identified — including tentative indication of a new "Negative peak 4" in the upper part of the Elliptica Subzone — and correlated with other sections confirming stability, respectively isochronity within carbon chemostratigraphy. • Upper Tithonian to middle Berriasian biostratigraphy and bioevents. • Sequence represents dynamic pelagic carbonate sedimentation in lower slope setting. • A new "Negative peak 4" of the δ13C carb values in the upper part of Elliptica Sbz. • Extensive normal polarity remagnetisation event with substantial clockwise rotation. [ABSTRACT FROM AUTHOR]

Abstract: This study summarizes the final results of magnetostratigraphic and biostratigraphic investigations of the Tithonian/Berriasian (J/K) boundary limestones at the locality of Puerto Escaño, Spain. The aim is to prepare the background for correlation of an upper Tithonian and lower Berriasian biostratigraphic zonation with global magnetoevents (manifested in detailed magnetostratigraphic profiles) between the Tethyan and the Boreal realms. Magnetostratigraphic studies were applied to an 8.1-m-thick part of the section embracing upper Tithonian and lower Berriasian strata. The average sampling interval was 30mm. The analysis of the IRM acquisition curves proved the presence of magnetite and hematite, the former mineral being the main carrier of the remanent magnetization. Progressive thermal demagnetization mostly revealed three NRM components, and magnetostratigraphy was based on the directions of the most stable of them, with unblocking temperature varying mostly from 300 to 540°C. Due to almost parallel beds, the fold test applied to this component did not give convincing results. In contrast, the reversal test received the best classification ‘A’. The detected polarity zones could has been unequivocally identified against the M-sequence of polarity intervals drawn from the Geomagnetic Polarity Time Scale 2004. This fact, together with the results of the reversal test, confirmed the ChRM to be the primary component. The sampled part of the section included a part of magnetozone M20r, full magnetozones M20n to M18r and a part of magnetozone M18n. Especially the detection of two reverse respectively by M20n.1r and M19n.1r with thicknesses only 40 and 90mm, respectively, required much effort when sampling the section. The calculated sedimentation rate varied from 1 to 5mm/ky. The positions of the individual events of tintinnoid biostratigraphy (mainly calpionellids) relative to the global magnetic polarity timescale are precisely defined. The base of the Calpionella Standard Zone, which is considered to be a potential J/K boundary indicator in ammonite-free sections from the Tethyan realm, or in sections where calpionellid stratigraphy applies, lies within magnetozone M19n at the level of 35% of its local thickness. None of the boundaries in the calpionellid zonation coincides precisely with any of those in the palaeomagnetic zonation, but the first appearance datum (FAD) of Calpionella grandalpina Nagy, indicating the base of the Intermedia Subzone, lies in close proximity to the base of magnetozone M19r. The last appearance datum (LAD) for Praetintinnopsella andrusovi Borza in Bed 14A corresponds approximately to the base of the Kysuca Subzone. [Copyright &y& Elsevier]