High resolution miospore stratigraphy of the Upper Famennian of eastern Belgium, and correlation with the conodont zonation.

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Abstract

The Ourthe valley in eastern Belgium provides the most complete exposures of the upper Famennian Condroz Group. A detailed miospore stratigraphy has been established for this succession. The lower three miospore biozones of the Upper Famennian (GF, VCo and VH Oppel Zones) are re-defined and subdivided into five new interval zones. The GF Oppel Zone which spans the Middle and Upper Famennian boundary was previously subdivided into three interval zones is now reduced to two. The highest Retispora macroreticulata (Mac) Interval Zone is now removed (due to its very sporadic occurrence) which results in the Grandispora microseta (Mic) Interval Zone of the GF Oppel Zone now being the lowest miospore interval zone of the Upper Famennian. The overlying VCo Oppel zone is subdivided into two new interval zones, the Rugospora radiata (Rad) and overlying Grandispora cornuta (Cor) interval Zones. A detailed study based on new and published material of the two nominal zonal taxa of the VCo Zone has clarified their morphology and resolved identification problems with other closely related Upper Devonian taxa. Furthermore, a biometric comparison of Grandispora cornuta with Grandispora tamarae has resulted in the specific diagnosis of G. cornuta being emended to increase its minimal spine length to 8 µm. The biostratigraphic implications for intercontinental correlations with the Upper Famennian of North America are discussed. The overlying VH Oppel Zone is subdivided into two new interval zones, the Apiculiretusispora verrucosa (Ver) Interval Zone and the overlying Vallatisporites hystricosus (Hys) Interval Zone. All of the new miospore interval zones are closely correlated with the well established conodont zones occurring in five sections of the Ourthe Valley. The new integrated data sets provide a high resolution biostratigraphy for the Upper Famennian stratigraphic interval in eastern Belgium.

Pour citer cet article

A propos de : Kenneth T. HIGGS

A propos de : Cyrille PRESTIANNI

A propos de : Maurice STREEL

A propos de : Jacques THOREZ