First record of a gladius-bearing coleoid Teudopsis bollensis Voltz (Cephalopoda, Coleoidea) in the Toarcian of the Western Carpathians (Slovakia)
ABSTRACT A fairly complete and relatively well-preserved gladius of the vampyropod coleoid cephalopod Teudopsis bollensis Voltz is recorded from the Lower Toarcian succession of the Kysuca Unit in the Pieniny Klippen Belt of Slovakia. These sediments are represented by dark-grey and black shales laid down in an oxygen-depleted environment during the Toarcian Oceanic Anoxic Event and potentially represent the first Jurassic ‘Konservat-Lagerstätte’ in the Western Carpathians. The first reliable record of the Early Jurassic genus Teudopsis from this area notably extends its palaeogeographic distribution to the northwestern continental margin of the Tethys Ocean. The systematics, palaeogeography and stratigraphy are briefly discussed in a European context.
- [Show abstract] [Hide abstract]
ABSTRACT: In this paper we present for the Austroalpine domain the Jurassic tectonostratigraphic evolution mirrored by sedi-mentary successions and basin evolution. The palaeogeo-graphic position together with characteristic litho- and microfacies features cause the lithostratigraphic definition of the different formations. For this reason for each formation the age range as well as their sedimentological and facies characteristics are documented in relation to the geodynamic and basin evolution. Strike and morphology of the facies zones in the Early to early Middle Jurassic followed the Triassic features. Only in the westernmost part of the Austroalpine domain ex-tensional tectonics led to the formation of the newly formed southeastern passive continental margin of the Penninic Ocean. In late Early resp. Middle Jurassic times the situation generally changed due to the partial closure of the Neotethys Ocean. The Austroalpine domain attained the lower plate position at that time. Due to ophiolite obduction this time span was characterized by a propagating thrust belt in front of the overriding ophiolite nappe stack. West-directed nappe thrusting caused the formation of deep-water trench-like basins in front of the prograding nappes which obliquely cut through former facies belts. Tectonic shortening de-creased in Late Jurassic times. In contrast to the Triassic evolution, Jurassic shallow-water carbonates are generally missing in the Austroalpine domain with exception of the Late Jurassic, when new shallow-water carbonate ramps and platforms established and sealed the main tectonic shortening structures. They existed until the Early Cretaceous. The Jurassic history of the Austroalpine domain mirrors the palaeogeographic position between two oceanic domains: A) to the west (northwest) the newly formed Penninic Ocean, where continental extension started around the Triassic/Jurassic boundary resp. in the Hettangian and first oceanic crust was formed in late Early Jurassic; and B) to the east (southeast) the Neotethys Ocean, in which the closure started before the Early/Middle Jurassic boundary with the onset of inneroceanic thrusting.
- [Show abstract] [Hide abstract]
ABSTRACT: The Pliensbachian–Toarcian interval was marked by major environmental disturbances and by a second-order mass extinction. Here, we reappraise the taxonomic, spatiotemporal and selective dynamics of extinctions over the whole interval, by analysing a high-resolution dataset of 772 ammonite species from NW Tethyan and Arctic domains. On average, 40–65% of ammonite species disappeared during each subchronozone, but higher extinction pulses (reaching 70–90%) prevailed from the Margaritatus to the Dispansum Chronozone. The main extinctions, corresponding to the Gibbosus, Pliensbachian–Toarcian boundary, Semicelatum, Bifrons–Variabilis, and Dispansum events, differed in their dynamics, suggesting episodes of ecological stress related to climate change, regression, disturbance in the carbon cycle or anoxia. The multi-pulsed volcanic activity in the Karoo–Ferrar province could well have triggered these ecological changes. In addition, ammonites experienced a morphological bottleneck during the Gibbosus event, 1 Ma before the Early Toarcian diversity collapse. Typically, drops in richness were related both to high extinctions and to declines in origination rates. This feature could result from strengthened ecological stresses related to the temporal overlap of environmental disturbances. After the Early Toarcian crisis, the recovery of ammonites was rapid (2 Ma) and probably influenced by a coeval marine transgression.Journal of the Geological Society 01/2010; 167:21-33. DOI:10.1144/0016-76492009-068 · 2.80 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: The Toarcian Oceanic Anoxic Event (T-OAE) (ca. 182 Myr, Early Jurassic) represents one of the best-recognized examples of greenhouse warming, decreased seawater oxygenation and mass extinction. The leading hypothesis to explain these changes is the massive injection of thermogenic or gas hydrate-derived 13C-depleted carbon into the atmosphere, resulting in a > 3 per mil negative carbon isotope excursion (CIE), accelerated nutrient input and dissolved oxygen consumption in the oceans. Nevertheless, the lack of a precisely dated record of the T-OAE outside low latitudes has led to considerable debate about both its temporal and spatial extent and hence concerning its underlying causes. Here we present new isotopic and lithological data from three precisely dated N Siberian sections, which demonstrate that mass extinction and onset of strong oxygen-deficiency occurred near synchronously in polar and most tropical sites and were intimately linked to the onset of a marked 6‰ negative CIE recorded by bulk organic carbon. Rock Eval pyrolysis data from Siberia and comparisons with low latitudes show that the CIE cannot be explained by the extent of stratification of the studied basins or changes in organic matter sourcing and suggest that the negative CIE reflects rapid 13C-depleted carbon injection to all exchangeable reservoirs. Sedimentological and palynological indicators show that the injection coincided with a change from cold (abundant glendonites and exotic boulder-sized clasts) to exceptionally warm conditions (dominance of the thermophyllic pollen genus Classopollis) in the Arctic, which likely triggered a rapid, possibly partly glacioeustatic sea-level rise. Comparisons with low latitude records reveal that warm climate conditions and poor marine oxygenation persisted in continental margins at least 600 kyr after the CIE, features that can be attributed to protracted and massive volcanic carbon dioxide degassing. Our data reveal that the T-OAE profoundly affected Arctic climate and oceanography and suggest that the CIE was a consequence of global and massive 13C-depleted carbon injection.Earth and Planetary Science Letters 12/2011; 312(s 1–2):102–113. DOI:10.1016/j.epsl.2011.09.050 · 4.72 Impact Factor