New constraints to the geodynamic evolution of the southern sector of the Calabria–Peloritani Arc (Italy)Nouvelles données sur l'évolution géodynamique du secteur méridional de l'Arc Calabro-Péloritain (Italie)

New studies have been carried out on the Tertiary of the Stilo Unit, the uppermost of the Calabria–Peloritani Arc southern sector, and the Stilo–Capo d'Orlando Formation, sealing the whole nappe stack. The Tertiary terrains linked to the Mesozoic cover of the Stilo Unit consist of the lowermost Oligocene Palizzi Formation and the Late Rupelian–Aquitanian Pignolo Formation. The possibility that they deposited before the emplacement of this unit as the highest tectonic sheet of the sector is suggested. The base of the Stilo–Capo d'Orlando Formation resulted of Burdigalian age in both type areas. This interpretation, together with the existing and new data, allows proposing an age close to the Aquitanian–Burdigalian boundary for the stacking of the whole Calabria–Peloritani Arc southern sector. To cite this article: G. Bonardi et al., C. R. Geoscience 334 (2002) 423–430.     

Calcareous nannofossils and the Santonian/Campanian and Campanian/Maastrichtian boundaries on the Brazilian Continental Margin: historical overview and state of the art

Recognition of the Campanian stage on the Brazilian Continental Margin, using calcareous nannofossils, has been historically problematic. This paper constitutes an overview of earlier works, showing how nannofossil biostratigraphic ideas have evolved since Troelsen & Quadros provided the first biozonation of this region in 1971. Recent studied have provided data which have helped to clarify these apparent biostratigraphic problems, and allows this region to be placed in a global biostratigraphic context.The earliest researchers identified the Santonian/Campanian boundary by the last occurrences of ‘Lithastrinus grillii’ andPetrobrasiella venata. P. venatawas later abandoned as an index species due to its rarity and, instead, the last occurrences ofMarthasterites furcatusand ‘Lithastrinus grillii’ became the most-used markers. However, the stratigraphic age of these biohorizons diverged from those quoted in the literature. In the Brazilian basins, these extinctions, rather than having occurred in the Campanian as was recorded elsewhere, were considered to mark the top of the Santonian, as suggested by correlations with other microfossil groups (primarily foraminifera and palynomorphs). To explain this phenomenon, the existence of a condensed sequence was postulated for most of the Brazilian marginal basins, where the uppermost Santonian deposits were apparently indistinguishable from those of the lowermost Campanian. In line with current correlations presented in the nannofossil literature, and with new information obtained from core and side-wall samples, it is now believed that the extinction of these speciesdidoccur in the Campanian in the Brazilian basins, whilst the last occurrence ofLithastrinus moratus(previously misidentified asLithastrinus grillii) has become a useful Santonian marker. Thus the Santonian/Campanian boundary in Brazil lies in a stratigraphic position similar to elsewhere in nannofossil terms, that is below CC18.The Campanian/Maastrichtian boundary was initially characterised in nannofossil terms in Brazil by the last occurrence ofBroinsonia parca constricta, and later by the last occurrence ofEiffellithus eximius. Recently acquired data has shown that the sequence of events in the Brazilian marginal basins is similar to that of the Sissingh/Perch-Nielsen standard biozonation scheme through this interval. Again, correlations in the literature with the recently defined boundary (in macrofossil terms) thus allow the boundary to be determined between the last occurrences ofBroinsonia parca constrictaandUniplanarius trifidus, that is, in CC23b.