This paper is a contribution to the redefinition of the base of Carboniferous system. At present the criterion for the definition of the Devonian–Carboniferous boundary is the first occurrence of a conodont species. In order to evaluate the stratigraphic potential for new criteria for the definition of the Devonian–Carboniferous boundary, the distribution of conodont species of Bispathodus, Branmehla, Palmatolepis, Polygnathus, Protognathodus, Pseudopolygnathus and Siphonodella across the boundary is presented and discussed. An updated biozonation scheme across the boundary based on the First Appearance of Bispathodus ac. aculeatus, Bispathodus costatus, Bispathodus ultimus, Protognathodus kockeli, Siphonodella bransoni and Siphonodella duplicata is proposed, and it is suggested that the new criterion for the definition of the base of the Carboniferous system be the First Appearance Datum of Pr. kockeli or Si. bransoni
The uppermost Famennian -lowermost Tournaisian interval has been analysed in detail using biostratigraphy, sedimentology, magnetic susceptibility and geochemistry in a reference section of the relatively shallow carbonate ramp environment within the Pomeranian Basin. High-resolution biostratigraphic study, based on miospores, allows recognition of the standard western European lepidophyta-nitidus (LN) and verrucosus-incohatus (VI) zones, as well as the Convolutispora major Zone, a local Pomeranian equivalent of the European standard hibernicus-distinctus (HD) Zone. The sedimentary succession and specific phenomena recognized close to the Devonian/Carboniferous boundary, such as fluctuations in water column euxinia, wildfire evidence, relative sea-level changes and perturbations of the carbon cycle reflected by positive carbon excursions, display a pattern partly similar to that observed in many areas in Europe during the Hangenberg Event, although the Hangenberg Black Shale horizon is not developed here. These important microscale environmental perturbations were observed not only within the Famennian LN miospore Zone but in a wide interval between the LN and the lowermost local Convolutispora major miospore zones ( = lower part of HD standard miospore Zone). It is still uncertain whether the recognized event(s) were connected solely with the Hangenberg Event, which was possibly complex and multi-phased as is sometimes suggested, or whether they represent a succession of regionally limited, post-Hangenberg events. This question needs to be further investigated on broader stratigraphic and geographical scales.
The Carboniferous sedimentary history of the Pomeranian Basin (NW Poland) begins with Hastarian open-marine carbonates and is terminated with ?lower Asbian terrestrial deposits in the north-eastern part and, ?upper Asbian or Brigantian, open-marine shales in the south-western part of the basin. The ?latest Viséan, Serpukhovian and early Bashkirian was a period of regional non-deposition and erosion. In the Upper Bashkirian-Gzhelian strata, an alluvial depositional environment was recognized.The Mississippian depositional history of the area has been punctuated by several, regional-scale events: (1) during the late Famennian-early Tournaisian times anoxic conditions developed over the entire basin. The results of both conodont and miospore studies show the presence of a stratigraphic gap within this sequence (which also show extremely reduced thicknesses), that comprises the uppermost Famennian (Middle and Upper praesulcata conodont zones) and the lowermost Hastarian (sulcata-sandbergi conodont zones). This stratigraphic gap probably resulted from some chemical and/or hydrodynamical factors rather than from any tectonic uplift; (2) volcanic activity on the nearby East European Craton (EEC), which was the source of large amounts of detrital (volcaniclastic) material supplied to the Pomeranian Basin during the Early crenulata-?early anchoralis-latus chrons (late Hastarian-early Ivorian), caused with time the gradual shallowing of the sedimentary environment. This shallowing trend began in the Early typicus Chron (early Ivorian) and terminated with terrestrial deposits in the early Asbian.The sedimentary succession and specific phenomena recognized in this structurally unstable basin, displays a pattern partly different from that observed in some areas in Europe. It would appear that other local factors, such as tectonic mobility of the hinterland area (EEC) and the Pomeranian Basin floor, were the possible causes of observed variations and relative sea-level changes.
A multidisciplinary study of the Devonian–Carboniferous boundary interval in pelagic successions of the Holy Cross Mountains and Sudetes and the ramp successions in the Western Pomerania region (Poland) is presented herein. The analysis applies the results of new palaeontological and biostratigraphic studies based mainly on conodonts, ammonoids and palynomorphs, biostratigraphic results interpreted earlier by different authors that have been re-examined, and geochemical and mineralogical characteristics, as well as magnetic susceptibility measurements across the Devonian–Carboniferous boundary interval. The study is focused on the interval from the Famennian ultimus conodont Zone to the Tournaisian duplicata conodont Zone, and from the Famennian lepidophyta–explanatus (LE) miospore Zone to the Tournaisian verrucosus–incohatus (VI) miospore Zone, respectively. The paper highlights sections, which are the most representative for the Devonian–Carboniferous boundary in each region, illustrates and summarises current knowledge on the uppermost Famennian to lowermost Tournaisian in these regions, gives data and correlation of the important stratigraphic markers for each region, and briefly correlates them outside the region. The sedimentary successions and specific phenomena, together with microscale environmental perturbations, recognised close to the Devonian/Carboniferous boundary in Poland, display a pattern similar to that observed in many areas in Europe during the Hangenberg Event.
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