A comparative analysis of some Late Carboniferous basins of Variscan Europe

Abstract

Vegetation diversity and pattern changes, and their relation to tectono-sedimentary histories are compared between selected Euramerican Late Palaeozoic coalfields, to understand better the controls on the dynamics of the Pennsylvanian terrestrial ecosystems and to demonstrate the problems with comparing data from various basins. The analysis is based on data from the following basins of different geotectonic and palaeogeographical positions: the cratonic Pennines Basin, the foreland South Wales and Upper Silesia basins, and the fault-related Intra Sudetic and Central and Western Bohemia basins. The analysis indicates that complex factors are responsible for changes in plant diversity and vegetation patterns. These are related to climate, tectonics, preservation potential, sampling biases and the current state of revision of the flora in each basin. Plant diversity patterns in the basins differ because of local controls and/or the character and detail of the available data. Maximum diversity varies among the basins within the Langsettian and Duckmantian substages. Two apparent step-like drops in diversity were detected within coal-bearing strata of most basins: at the Duckmantian/Bolsovian boundary and at the Bolsovian/Asturian boundary. Further and more prominent falls are related to transitions from coal-bearing to non-coal-bearing (mostly red bed) strata or vice versa during Stephanian times. Interpretation of climatic signals recorded in the sedimentary successions indicates that Westphalian and middle Stephanian times were wet intervals, whereas early and late Stephanian times were drier.

Wetland-Dryland Vegetational Dynamics in the Pennsylvanian Ice Age Tropics

“…Yet farther to the east, in central Pangea, the nature of glacial-interglacial cyclicity, on the finest scales, becomes increasingly difficult to recognize because of the complexity of the landscape in and around the Variscan portion of the Central Pangean Mountains and the overprint of syndepositional tectonics in some portions (Stollhofen et al 1999;Opluštil 2005;Opluštil and Cleal 2007;. Even so, changes in climate and sedimentation patterns can be recognized to varying degrees in these areas and related to glacial-interglacial controls at various spatiotemporal scales (Oyarzun et al 1999;Stollhoffen et al 1999;Roscher and Schneider 2006;Bertier et al 2008;Gastaldo et al 2009;van Hoof et al 2012;Opluštil et al 2013b).…”

“…These floras are drawn almost entirely from wetland evolutionary lineages, even if some species and genera of pteridosperms and ferns are rarely found in typically lowland wetland settings from the interior Pangean and marginal-Variscan flatlands (Cleal 2008b;Š imů nek and Cleal 2011). It has been hypothesized that the steep walls of these narrow basins supported a flora that, though adapted to wet climates, was specialized for growth under conditions of less waterlogging than found in the basin floors, where coals developed (Opluštil and Cleal 2007). These assemblages, however, lack elements typical of the seasonally dry flora, mainly conifers or known minor associates of the dominant elements.…”

On the fundamental difference between coal rank and coal type

“…The physical and biological dynamics of this time were superimposed on the complex low-latitude landscape where a vast amount of Pennsylvanian peat formed (e.g., Cecil et al, 2003a;Cleal et al, 2009;Gastaldo et al, 1993;Greb et al, 1999Greb et al, , 2003Greb et al, , 2008Staub, 2002). The Euramerican portion of this landscape included the Variscan-Appalachian mountain ranges, subparallel to the equator (Opluštil and Cleal, 2007), creating large areas of both cratonic and intermontane basins for peat formation in Europe and southeastern Canada (Bashforth et al, 2010;Calder, 1994;Opluštil and Cleal, 2007;Piedad-Sánchez et al, 2004;Roscher and Schneider, 2006), and the large cratonic basins in the United States, in which many of the major coal beds, particularly in the Middle Pennsylvanian, developed on flat landscapes often of vast areal extent (Belt et al, 2011;Calder and Gibling, 1994;Cecil et al, 1985Cecil et al, , 2003bGreb et al, 2003;Heckel, 1995Heckel, , 2008Staub, 2002). Climatic fluctuations, sea-level fluctuations, changes in siliciclastic sediment flux, and the formation of peat and limestone, were not independent variables (Cecil and Dulong, 2003).…”

Palaeoecology of Macroneuropteris scheuchzeri, and its implications for resolving the paradox of ‘xeromorphic’ plants in Pennsylvanian wetlands

“…The late Moscovian-Kasimovian was a time of significant uplift of the Variscan mountain range in centralthrough-western Europe (Cleal et al, 2009;Falcon-Lang et al, 2012). Thus, the disappearance and failure to return of such a formerly widespread and abundant species suggests that there may have been migrational barriers between wetlands in the uplifting Variscan Foreland, where M. scheuchzeri had been abundant earlier, and those of intermontane basins and areas south of the Variscan Orogen, which mostly developed in the Moscovian-Kasimovian (Opluštil and Cleal, 2007).…”