The biostratigraphic and palaeoenvironmental study of microfossils contained in the "Silt di Verrua Savoia" and in the overlaying "Calcareniti di Castel Verrua", cropping out in a wide quarry front near Verrua Savoia (Turin, Piedmont), has allowed us to refer most of the succession to the MPl3 Biozone of the early Pliocene, on the basis of the co-occurence of Hirsutella margaritae and Globoconella puncticulata. Only the Calcareniti top seems referable to the MPl4a Biozone, owing to the presence of the only G. puncticulata. Foraminifer and ostracod assemblages suggest, for the lower part of the silty unit, a depositional environment placed between the deep outer neritic zone and the upper epibathyal zone. In the top part of "Silt of Verrua Savoia", where sandy and calcareous sandstone levels already come out, microfossils of finer levels point out a passage to an outer neritic palaeoenvironment. Also most of the overlying "Calcareniti of Castel Verrua" are referable to the outer neritic zone. A further palaeobathymetry decrease seems to occur only in the upper part of the succession, where assemblages are indicative of inner-outer neritic zone. The comparison between sections sampled at the two sides of the quarry (Section A, NW, Sections B and C, SE) points out some differences and suggests for the Section B a depositional palaeoenvironment slightly less deep and more influenced by shallow waters than that documented in the Section A.
Lo studio biostratigrafico e paleoambientale dei microfossili conservati nei Silt di Verrua Savoia e nelle sovrastanti Calcareniti di Castel Verrua, affioranti in un ampio fronte di cava presso Verrua Savoia (Torino, Piemonte), ha permesso di attribuire la maggior parte della successione alla Biozona MPl3 del Pliocene inferiore. Solo la parte sommitale delle Calcareniti sembra correlabile alla Biozona MPl4a. Le associazioni a foraminiferi e ostracodi indicano una progressiva riduzione della paleobatimetria, da un ambiente circalitorale profondo-epibatiale superiore a circalitorale e, infine, al limite tra infra-circalitorale. Il confronto tra le sezioni campionate ai due lati della cava (Sez. A a NO, Sez. B e Sez. C a SE) mette in evidenza alcune differenze e suggerisce un ambiente leggermente meno profondo, più interessato da apporti da acque basse per la Sez. B.
Le associazioni plioceniche a foraminiferi e ostracodi di Verrua Savoia (Piemonte, Italia NW): analisi biostratigrafica e paleoambientale.
Violanti D
2005
Abstract
The biostratigraphic and palaeoenvironmental study of microfossils contained in the "Silt di Verrua Savoia" and in the overlaying "Calcareniti di Castel Verrua", cropping out in a wide quarry front near Verrua Savoia (Turin, Piedmont), has allowed us to refer most of the succession to the MPl3 Biozone of the early Pliocene, on the basis of the co-occurence of Hirsutella margaritae and Globoconella puncticulata. Only the Calcareniti top seems referable to the MPl4a Biozone, owing to the presence of the only G. puncticulata. Foraminifer and ostracod assemblages suggest, for the lower part of the silty unit, a depositional environment placed between the deep outer neritic zone and the upper epibathyal zone. In the top part of "Silt of Verrua Savoia", where sandy and calcareous sandstone levels already come out, microfossils of finer levels point out a passage to an outer neritic palaeoenvironment. Also most of the overlying "Calcareniti of Castel Verrua" are referable to the outer neritic zone. A further palaeobathymetry decrease seems to occur only in the upper part of the succession, where assemblages are indicative of inner-outer neritic zone. The comparison between sections sampled at the two sides of the quarry (Section A, NW, Sections B and C, SE) points out some differences and suggests for the Section B a depositional palaeoenvironment slightly less deep and more influenced by shallow waters than that documented in the Section A.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
