High-resolution ammonite, belemnite and stable isotope record from the most complete Upper Jurassic section of the Bakony Mts (Transdanubian Range, Hungary)

Abstract

This research focuses on the cephalopod fauna and biostratigraphy of the latest Jurassic succession of the Lókút Hill (Bakony Mts, Transdanubia, Hungary). Fossils were collected bed-by-bed from Ammonitico Rosso facies and from the subsequent Biancone type rock. The poorly preserved cephalopods from the lowermost part of the profile, immediately above the radiolarite, may represent a part of the Oxfordian stage. The rich Kimmeridgian ammonite fauna is published for the first time while the formerly illustrated Tithonian fauna is revised. All the successive Kimmeridgian and Early Tithonian Mediterranean ammonite zones can be traced. The highest documented ammonite zone is the Late Tithonian Microcanthum Zone. The beds above yielded no cephalopods. Particular attention was paid to the belemnite fauna of over 120 specimens collected under strict ammonite control. Among the belemnite faunas an Early Tithonian, an early middle Tithonian, a late middle Tithonian, and a latest Tithonian assemblage can be distinguished. Thereby, an association is distinguished in the middle Late Kimmeridgian and one that characterizes the Oxfordian-Kimmeridgian boundary beds. The main difference from previously published belemnite data appears to be that the Hungarian assemblages are impoverished with respect to contemporary faunas from Italy and Spain (Mediterranean Province). An isotopic analysis of the belemnites show that the carbon-isotope data are consistent with carbon-isotope stratigraphies of the Western Tethys and show a decrease in values towards the Jurassic-Cretaceous boundary.

Carbon cycle history through the Jurassic–Cretaceous boundary: A new global δ13C stack

“…The belemnite fauna allowed the recognition of four belemnites assemblages (TiBA-I to TiBA-IV) for the Tithonian part . Range charts showing the distribution of the complete ammonoid and belemnite fauna were presented in Főzy et al (2011).…”

“…The beds gently dip (20°) to the north. Biostratigraphic data from the Tithonian part of the section were first provided by Vigh (1984), later amended and complemented by late Oxfordian and Kimmeridgian cephalopod data by Főzy et al (2011). In addition, rabowski et al (2010a) developed a calpionellid biostratigraphy and magnetostratigraphy for the Tithonian-Berriasian part of the section.…”

“…Higher up-section, a return towards more positive values up to 0.7‰ is observed. iostratigraphic data (Vigh, 1984;Főzy et al, 2011;rabowski et al, 2010a) together with magnetostratigraphic data (Grabowski et al, 2010a) allow us to accurately place the low point seen in the carbon isotope curve within these schemes. This minimum appears in the upper part of …”

“…= Parastomiosphaera malmica Zone. elemnite assemblages are from Főzy et al (2011). biostratigraphy (from Horváth andKnauer, 1986, Főzy, 1990) and carbon and oxygen isotope curves.…”

New species of lower Tithonian macroconchiateHybonoticerasfrom Mexico and the co-occurrence ofMazapilitesandHybonoticerasin the Mexico-Caribbean area

“…2.1). Such an interpretation can be recognized in the illustrations and/or synonymy lists by Oppel (1863), Benecke (1866), Favre (1877), Di Stefano (1883), Valduga (1954), Barthel (1959), Berckhemer and Hölder (1959), Collignon (1959, at least for H. laevigatum Collignon, 1959), Stephanov (1959), Enay et al (1971, 2005), Olóriz (1978), Sapunov (1979), Mariotti et al (1979), Rossi (1984), Sarti (1984, 1985), Verma and Westermann (1984), Geyssant in De Wever et al (1986), Howarth (1992, 1998), Pathak (1993), Wierzbowski (1994), Benzagaggh and Atrops (1997), Caracuel and Olóriz (1999), Cecca (1999), Benzagaggh (2000), Zeiss (2001), Enay (2009), Fözy et al (2011), Grigore (2011), and Schweigert et al (2012), among others. Revision based on well-preserved material collected bed-by-bed is needed to propose a precise interpretation (e.g., Zeiss, 2001), which must be based on population-level data to reach a conclusive evaluation of phenotype variability in the Oppel species.…”