Geertekerkhof 14bis


Geertekerkhof 14bis

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Bujtor L.,University of Pécs | Janssen N.M.M.,Geertekerkhof 14bis | Verreussel R.M.C.H.,TNO
Neues Jahrbuch fur Geologie und Palaontologie - Abhandlungen | Year: 2013

The first record of belemnites from fossil hydrothermal vent sites in the Mecsek Mountains of Hungary emphasizes the occurrences of belemnites in Mesozoic chemosynthetic-microbial based ecosystems reported only from cold seep carbonates to date. From the outer shelf-upper bathyal (<300 m) hydrothermal vent site latest Valanginian - Early Hauterivian taxa Adiakritobelus (?), Hibolithes, Duvalia, and Pseudobelus (belemnites) and organic-walled dinoflagellate cysts (a.o. Spiniferites dentatus) are reported. The laterally extending hemipelagic facies yielded latest Berriasian and earliest Valanginian taxa, like: Duvalia, Pseudobelus, and Berriasibelus. The reported belemnite assemblage from this vent site and its coeval beds dated the time span of the iron-ore formation and venting more precisely, between the Early Valanginian and earliest Hauterivian. The belemnite and dinoflagellate cyst assemblages are typical of the Mediterranean Province of the Tethyan Realm. © 2013 E. Schweizerbart'sche Verlagsbuchhandlung, Stuttgart, Germany.

Price G.D.,University of Plymouth | Fozy I.,Hungarian Natural History Museum | Janssen N.M.M.,Geertekerkhof 14bis | Palfy J.,Eötvös Loránd University | Palfy J.,Hungarian Academy of Sciences
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2011

A high resolution stable isotope study of Upper Valanginian-Barremian (Early Cretaceous) belemnites from Bersek Quarry (Gerecse Mountains, Transdanubian Range, Hungary) is presented. Over 190 belemnite rostra (including Hibolithes subfusiformis, Duvalia dilatata and Conohibolites gladiiformis) have been analysed for oxygen and carbon isotopes and for trace element geochemistry. The obtained carbon isotope curve shows a long term decrease from ~. 1.2‰ in the Upper Valanginian to ~-0.5‰ in the Upper Hauterivian followed by more variable values in the Early Barremian. Superimposed on this trend are a number of possible shorter term peaks. This pattern broadly follows published carbon isotope curves for the same interval and is therefore thought to reflect a global rather than a regional signal. The oxygen isotopes show the most positive values in the uppermost Valanginian and become increasingly more negative through the Hauterivian into the Barremian. Such changes are interpreted as an increase in marine temperatures through the section. The Mg/Ca data paralleling the oxygen isotope trend confirms our temperature interpretation. The oxygen isotope ratios are generally more negative and therefore allow us to infer warmer temperatures, than those derived from belemnites from time equivalent sections in Germany and Speeton, UK, consistent with the more southerly latitudinal position of the Gerecse Mts. within the Tethys Ocean. The oxygen isotope and Mg/Ca data also reveal habitat differences for the different belemnite groups analysed. Vaunagites pistilliformis, ". Belemnites" pistilliformis and Hibolithes typically have more negative oxygen isotope values than Pseudobelus and Duvalia and are therefore interpreted to have lived in warmer and/or shallower parts of the water column, consistent with previous interpretations. © 2011 Elsevier B.V.

Fozy I.,Hungarian Natural History Museum | Janssen N.M.M.,Geertekerkhof 14bis | Price G.D.,University of Plymouth
Geologica Carpathica | Year: 2011

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.

Bodin S.,Ruhr University Bochum | Meissner P.,Ruhr University Bochum | Janssen N.M.M.,Geertekerkhof 14bis | Steuber T.,The Petroleum Institute | Mutterlose J.,Ruhr University Bochum
Global and Planetary Change | Year: 2015

There is an abundance of evidence for short intervals of cold climatic conditions during the Early Cretaceous. However, the lack of a high-resolution, long-term Early Cretaceous paleotemperature record hampers a full-scale synthesis of these putative "cold snap" episodes, as well as a more holistic approach to Early Cretaceous climate changes. We present an extended compilation of belemnite-based oxygen, carbon and strontium isotope records covering the Berriasian-middle Albian from the Vocontian Basin (SE France). This dataset clearly demonstrates three intervals of cold climatic conditions during the Early Cretaceous (late Valanginian-earliest Hauterivian, late early Aptian, latest Aptian-earliest Albian). Each of these intervals is associated with rapid and high amplitude sea-level fluctuations, supporting the hypothesis of transient growth of polar ice caps during the Early Cretaceous. As evidenced by positive carbon isotope excursions, each cold episode is associated with enhanced burial of organic matter on a global scale. Moreover, there is a relatively good match between the timing and size of large igneous province eruptions and the amplitude of Early Cretaceous warming episodes. Altogether, these observations confirm the instrumental role of atmospheric CO2 variations in driving Early Cretaceous climate change. From a long-term perspective, the coupling of global paleotemperature and seawater strontium isotopic ratio during the Early Cretaceous is best explained by temperature-controlled changes of continental crust weathering rates. © 2015 Elsevier B.V..

This paper deals with the distribution of belemnites in the latest Hauterivian to early Bedoulian of the Angles Barremian Stratotype Section (ABSS). The distribution of the belemnites in the ABSS is not uniform, mainly due to the inaccessibility of certain beds. To cover this, and to compare the distribution with more proximal settings, we investigated a section to the north of Le Bourguet. The latest Hauterivian sediments mainly yield Hibolithes ex gr. subfusiformis besides some Duvalia ex gr. dilatata. The earliest Barremian sediments deliver a richer association that yields the last Hibolithes spp. The first typical Barremian belemnites occur just one bed above the Hauterivian-Barremian boundary based on ammonites. This belemnite association (BaBA1) consists of Duvalia ex gr. silesiacagagrica, Duvalia pontica and several species of Hibolithes. At the boundary between the Nicklesia pulchella and the Kotetishvilia compressissima zones the diversity increases and the first classical Barremian belemnites occur. These were formerly attributed to Mesohibolites (BaBA2). These species are herein attributed to a new genus Shvetsovia. Together with the duvaliids from BaBA1 they were first described from Abkhasia by SHVETSOV (1913). The latest Early Barremian (BaBA3) and the earliest Late Barremian (BaBA4) show well diversified belemnite associations, with many classical species, dominated by few genera closely resembling the true Mesohibolites. Eventually, these belemnite associations are compared to more proximal sections within the Vocontian Basin, and areas outside the Vocontian Basin (chiefly Hungary and Georgia). Some differences in the frequency and abundance of several species in these different palaeogeographical settings are believed to indicate differences in natural habitat. Duvalia ex gr. grasiana appears to be more abundant in more distal sections, while juvenile Mesohibolitidae, Conohibolites and Curtohibolites appear to be more abundant in the more proximal environments. Finally, a biozonation is presented and defined based on the distribution of the belemnites in the ABSS. This biozonation appears applicable in the more proximal sections, although some biozones are diachronous. The first Mesohibolites occur in the Upper Barremian Imerites giraudi Zone. In the Barremian-Bedoulian boundary sediments, as defined in the ABSS, Neohibolites first occurs, but the latter is only dominant in the marly sediments above the "calcareous Bedoulian". In the Late Barremian-early Bedoulian seven main belemnite associations can be distinguished, viz. BaBA5, BaBA6, BaBA7, BdBA1, BdBA2, BdBA3 and BdBA4. The following new species and genera are described: Hibolithes keleptrishvilii sp. nov. (latest Hauterivian), Duvalia vermeuleni sp. nov. (Early Barremian), Curtohibolites (?) bourguetensis sp. nov. (Early Barremian), and Shvetsovia gen. nov. (late Early-early Late Barremian). Besides, the Late Barremian yields the new species Mesohibolites anglesensis. Moreover, eleven species are described in open-nomenclature.

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