Sequence Stratigraphy and Onlap History of the Donets Basin, Ukraine: Insight into Carboniferous Icehouse Dynamics

The degree to which Permo-Carboniferous cyclothemic successions archive evidence for long-term variations in ice volume during the Late Paleozoic Ice Age is insufficiently resolved. Here we develop the sequence stratigraphy and onlap-offlap history for a 33-my interval of the Carboniferous using the U-Pb calibrated succession of the Donets Basin, Ukraine, in order to assess the relationship between sea-level, high-latitude changes in glacial extent, and climate. Integrated subsurface and outcrop data permit meter-scale correlation of 242 biostratigraphically constrained limestones and coals, and in turn individual cyclothems, across ~250 km of the Donets Basin. Rapid uniform subsidence and basinwide continuity of marker beds indicate Pennsylvanian deposition under relatively stable tectonic conditions. Three scales of sequences (avg. durations of ~140 ky, ~480 ky and 1.6 my) are recognized on the basis of stratigraphic stacking patterns and basinwide architecture of marine to terrestrial facies assemblages. The hierarchy of sequences and the geographic and stratigraphic positions of shifts in base-level sensitive facies across the Donets ramp permit the construction of an onlap-offlap history at a sub-400 ky scale. Major sea-level lowstands occur across the mid-Carboniferous boundary and during the early Moscovian. These lowstands coincide with glacial maxima inferred from high-latitude glacigenic deposits. The middle to late Pennsylvanian is characterized by a stepwise onlap, culminating in an earliest Gzhelian highstand, suggesting contraction of Carboniferous ice sheets prior to the initiation of Early Permian glaciation. The stratigraphic position of climate sensitive facies within individual Donets cyclothems indicates a turnover from seasonal sub-humid or semi-arid climate to everwet conditions during the late lowstand and maximum ice sheet accumulation. Comparison of the stratigraphic and aerial distribution of coals and evaporites in the Donets Basin with the onlap-offlap history further indicates everwet conditions during lowstands and inferred glacial maxima and drier climate during onlap and inferred ice sheet contraction at the intermediate (~0.8 to 1.6 my) and long (106 yr) time-scales. Taken together, the relationship between inferred climate and glacioeustasy suggests a likely teleconnection between high-latitude ice sheet behavior and low-latitude atmospheric dynamics

Cladistic tests of monophyly and relationships of biostratigraphically significant conodonts using multielement skeletal data: Lochriea homopunctatus and the genus Lochriea

Since the 1960s, huge progress has been made in reconstructing the multielement skeletons of conodont species and developing a biologically defensible taxonomy. Nevertheless, a widespread prejudice remains that certain parts of the conodont skeleton, particularly the P1 elements, are more informative than others with regard to taxonomy and evolutionary relationships. Here, we test these views. A new partial multielement reconstruction of the skeleton of the biostratigraphically significant conodont originally described as Gnathodus commutatus homopunctatus allows us to conduct a cladistic test of the alternative hypotheses of phylogenetic placement of this species. Our analysis also provides the first test of the hypothesis that Lochriea– species of which are markers for global correlation – is monophyletic and tests hypotheses concerning the origins of the genus. Our results demonstrate that homopunctatus is a species of Lochriea and that the genus is monophyletic. The widely held view that Lochriea arose from a species of Bispathodus is not supported. Our results show that it is difficult to predict a priori which parts of the conodont skeleton carry phylogenetic signal, and provide strong support for the hypothesis that similarity in the morphology of conodont P1 elements alone is not a reliable guide to relationships and taxonomic groupings of conodont species. This is because P1 elements with similar morphologies are convergently acquired in multiple conodont clades, because reliance on the characters of only one of the six or seven morphologically distinct elements of the conodont skeleton ignores phylogenetically significant data and because P1 elements can lack characters that might seem to be diagnostic of a genus. Conodonts are no different to other organisms: ignoring data that have the potential to be phylogenetically informative is unlikely to produce the most reliable hypotheses of evolutionary relationships. We suggest that other biostratigraphically significant hypotheses of relationship between conodont taxa that are based on P1 elements alone should be subject to cladistic testing

Global time scale and regional stratigraphic reference scales of Central and West Europe, East Europe, Tethys, South China, and North America as used in the Devonian-Carboniferous-Permian Correlation Chart 2003 (DCP 2003)

The boundaries of the Devonian, Carboniferous, and Permian stages of the Global Stratigraphic Reference Scale (abbreviated to Global Stratigraphic Scale-GSS) are described in relation to the biostratigraphic and/or lithostratigraphic units of the Regional Stratigraphic Reference Scales (abbreviated to Regional Stratigraphic Scales-RSS) of Central and West Europe, East Europe, Tethys, South China (eastern Tethys), and North America. In their type regions the boundaries of GSS units rarely coincide with those of homonymous RSS units. Moreover, the definitions of some RSS units have changed several times over the last decades, and subsequent misunderstanding of the stratigraphical significance of these changes has often introduced errors into proposed global correlation charts. The stratigraphic framework proposed in our global Devonian-Carboniferous-Permian Correlation Chart 2003 [DCP 2003 (Devonian-Carboniferous-Permian Correlation Chart 2003, Menning, M., Schneider, J. W., Alekseev, A. S., Amon, E. O., Becker, G., von Bitter, P. H., Boardman, D. R., Bogoslovskaya, M., Braun, A., Brocke, R., Chernykh, V., Chuvashov, B. I., Clayton, G., Dusar, M., Davydov, V. I., Dybova-Jachowicz, S., Forke, H. C., Gibling, M., Gilmour, E. H., Goretzki, J., Grunt, T. A., Hance, L., Heckel, P. H., Izokh, N. G., Jansen, U., Jin Y.-G., Jones, P., Käding, K.-Ch., Kerp, H., Kiersnowski, H., Klets, A., Klug, Ch., Korn, D., Kossovaya, O., Kotlyar, G. V., Kozur, H. W., Laveine, J.-P., Martens, Th., Nemyrovska, T. I., Nigmadganov, A. I., Paech, H.-J., Peryt, T. M., Rohn, R., Roscher, M., Rubidge, B., Schiappa, T. A., Schindler, E., Skompski, S., Ueno, K., Utting, J., Vdovenko, M. V., Villa, E., Voigt, S., Wahlman, G. P., Wardlaw, B. R., Warrington, G., Weddige, K., Werneburg, R., Weyer, D., Wilde, V., Winkler Prins, C. F., Work, D. M., 2004). Abschlußkolloquium DFG-Schwerpunktprogramm 1054: Evolution des Systems Erde während des jüngeren Paläozoikums im Spiegel der Sedimentgeochemie. Abstracts Univ. Erlangen, Germany, 2004, p. 43.] (herein abbreviated to DCP 2003, and cited as DCP, 2003 in references) is an attempt to reduce these errors. The DCP 2003 is the stratigraphic base for Project 1054 of the Deutsche Forschungsgemeinschaft (DFG) "The evolution of the Late Palaeozoic in the light of sedimentary geochemistry". This composite time scale has been carefully balanced, as far as data allows, to remove unnecessary, artificial compression and expansion of time intervals, biozonations and depositional events. The ages selected in DCP 2003 are markedly different to those in the Geologic Time Scale 1989 [GTS 1989 (Harland, W.B., Armstrong, R.L., Cox, A.V., Craig, L.E., Smith, A.G., Smith, D.G., 1990). A geologic time scale 1989. Cambridge Univ. Press, Cambridge.; Harland, W.B., Armstrong, R.L., Cox, A.V., Craig, L.E., Smith, A.G., Smith, D.G., 1990. A geologic time scale 1989. Cambridge Univ. Press, Cambridge, pp. 1-263.] and in Gradstein and Ogg [Gradstein, F.M., Ogg, J., 1996. A Phanerozoic time scale. Episodes 19 (1/2), 3-4, insert.), whereas they are closer to those of the Geologic Time Scale 2004 [GTS 2004; Gradstein, F.M., Ogg, J.G., Smith, A.G., 2004. A Geologic Time Scale 2004. Cambridge Univ. Press, Cambridge, pp. 1-589.]. Mostly, the ages are rounded to the nearest 0.5 Ma in order to avoid estimates of questionable accuracy, whereas ages of 0.1 Ma in the GTS 2004 and their error bars of ± 0.4 Ma to ± 2.8 Ma for the Devonian to Permian stage boundaries suggest an improved accuracy. In contrast, in the DCP 2003 questionable ages and positions of stratigraphic boundaries are marked by arrows