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Westphalian-Stephanian macrofloras of the Southern Pennines Basin, UK

Cleal C.J.

Studia Geologica Polonica

2008

Vol. 129

25-41

The southern part of the Pennines Basin (Warwickshire, South Staffordshire and Wyre Forest coalfields) has a condensed succession of middle Langsettian to upper Asturian or lower Cantabrian strata. The Langsettian-Duckmantian part of the succession is in a grey coal-bearing facies, in which many coal seams have become vertically accreted, and in which macrofloras of the Laveineopteris loshii Subzone, Lonchopteris rugosa Zone and Neuropteris semireticulata Subzone can be recognised. Species composition and Total Species Richness diversity curves compare well with those from the Central Pennines Basin to the north, suggesting that they represent an essentially unified area of vegetation. Red beds of the Etruria Formation appear in the lower Bolsovian Substage (stratigraphically lower in the marginal southernmost part of the basin). The Etruria Formation macrofloras are not abundant, but where they do occur are not significantly less species-rich than in the contemporaneous grey coal-bearing sequence in the Central Pennines. The Etruria Formation macrofloras belong to the N. semireticulata Subzone, and there is no evidence of the overlying Laveineopters rarinervis Subzone that would indicate a late Bolsovian age. The grey, mainly arenaceous Halesowen Formation unconformably overlies the Etruria Formation, and yields low- diversity macrofloras that probably indicate the late Asturian Dicksonites plueckenetii Subzone. The succeeding red-beds of the Salop Formation yield even lower diversity macrofloras, but there is some evidence that they may belong to the Cantabrian O. cantabrica Zone. A comparison of these new data with the evidence from the Central Pennines helps confirm the robustness of Total Species Richness as a proxy for environmental change in Late Carboniferous palaeotropical coal-bearing sequences.

Macrofloral biostratigraphy of the Ottweiler Group in Saar-Lorraine and its consequences for Stephanian palynostratigraphy and geochronology

Cleal C.J.

Studia Geologica Polonica

2008

Vol. 129

9-23

A revised macrofloral biostratigraphy for the Stephanian Ottweiler Group of the Saar- Lorraine Coalfield places most of the succession in the upper Stephanian B Substage (Alethopteris zeilleri Zone). Only the Breitenbach Formation at the top of the Group indicates a position in the middle Stephanian C Substage (Sphenophyllum angustifolium Zone). These revised correlations now make the tonstein date for the Wahlschied Seam, one of the few reliable radiometric dates for the Stephanian Stage, compatible with the recently proposed Carboniferous time scales. It also explains the large time gap at the base of the Holz Conglomerate suggested by the radiometric dates. There is now little evidence that the palynological ST Zone extends lower than the Stephanian B Substage, and that there appears to be a gap in the palynological zonation between the lower Cantabrian and top of the Barruelian Substages.