Thin continental Carboniferous sequences crop out sparsely in the western Southern Alps (Alpe Logone, Mesenzana, Grantola, Bosco Valtravaglia-Fabiasco,Val Tresa, etc.) and are currently the subject of a detailed litho- and biostratigraphic revision, to reconsider their chronological position with respect to previously published age constraints. The age of these Upper Palaeozoic sedimentary successions, scattered over a wide area and strongly tectonized along major structural lineaments, has long been debated between Westphalian and Stephanian. The present work focuses mainly on the palynology of the Brezzo di Bèdero section (Luino, Lake Maggiore). The recovered palynoflora is assigned to 42 spore genera and 76 species of which one genus and 10 species are newly proposed. Fifty-seven spore species and 19 pollen species are described and illustrated. Qualitatively, the Bèdero palynoflora shows strong affinities to those ofWestern Europe. The most abundant palynomorphs are trilete spores known to be characteristics of the late Westphalian and early Stephanian assemblages. These are characterized by the remarkable presence of Florinites and subordinately Wilsonites species, low numbers of Potonieisporites, rare Limitisporites and Vesicaspora, and very rare Latensina-Cordaitina pollen. The occurrence of diverse monolete spores Laevigatosporites, Punctatosporites, Spinosporites, Thymospora and Torispora, with common Lundbladispora gigantea, L. simonii, Stenozonotriletes rubius n. sp. together with the absence of plicate and taeniate pollen grains suggests a strong resemblance to the late Westphalian–early Stephanian interval assigned to the OT Zone of Western Europe. Variations in the quantitative composition can be likely attributed to variations in the environmental setting with regards to non-forming peat deposits. The palynological suite is indicative of the existence of a well-established lowland Cordaiteans vegetation and well settled pterophytic, pteridosperm and subordinately sphenophytic and lycophytic, hygrophytic plant communities.
Miospore assemblages of the Bedero section Varese, Upper Carboniferous from Southern Alps, Italy
PITTAU, PAOLA;
2008-01-01
Abstract
Thin continental Carboniferous sequences crop out sparsely in the western Southern Alps (Alpe Logone, Mesenzana, Grantola, Bosco Valtravaglia-Fabiasco,Val Tresa, etc.) and are currently the subject of a detailed litho- and biostratigraphic revision, to reconsider their chronological position with respect to previously published age constraints. The age of these Upper Palaeozoic sedimentary successions, scattered over a wide area and strongly tectonized along major structural lineaments, has long been debated between Westphalian and Stephanian. The present work focuses mainly on the palynology of the Brezzo di Bèdero section (Luino, Lake Maggiore). The recovered palynoflora is assigned to 42 spore genera and 76 species of which one genus and 10 species are newly proposed. Fifty-seven spore species and 19 pollen species are described and illustrated. Qualitatively, the Bèdero palynoflora shows strong affinities to those ofWestern Europe. The most abundant palynomorphs are trilete spores known to be characteristics of the late Westphalian and early Stephanian assemblages. These are characterized by the remarkable presence of Florinites and subordinately Wilsonites species, low numbers of Potonieisporites, rare Limitisporites and Vesicaspora, and very rare Latensina-Cordaitina pollen. The occurrence of diverse monolete spores Laevigatosporites, Punctatosporites, Spinosporites, Thymospora and Torispora, with common Lundbladispora gigantea, L. simonii, Stenozonotriletes rubius n. sp. together with the absence of plicate and taeniate pollen grains suggests a strong resemblance to the late Westphalian–early Stephanian interval assigned to the OT Zone of Western Europe. Variations in the quantitative composition can be likely attributed to variations in the environmental setting with regards to non-forming peat deposits. The palynological suite is indicative of the existence of a well-established lowland Cordaiteans vegetation and well settled pterophytic, pteridosperm and subordinately sphenophytic and lycophytic, hygrophytic plant communities.
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