In the Northern Apennine fold and thrust belt, the post-collisional stages are characterized by the Oligocene–Pliocene progressive shortening and shifting of the foredeep basins, resulting from the eastward migration of the orogenic front toward the belt foreland represented by the Adria plate continental margin. The foredeep deposits were involved in the tectonic stack as thrust sheets detached from their substrate and overthrust by the Ligurian Units derived from the Jurassic Ligure-Piemontese oceanic basin. The Eocene-Oligocene succession of the Modino Unit (Tuscan Domain of the Northern Apennine) is composed by turbidites deposited on top of the Apenninic prism during the early collisional and postcollisional stages. The biostratigraphical, and petrographycal analysis of different stratigraphic sections of the Modino Unit Succession enables us to give a paleotectonic reconstruction of the evolution of this part of the foredeep. The use of calcareous nannofossils help us recognize most of the biostratigraphic units using the Chronostratigraphic Global Chart with the biohorizons developed for the Mediterranean region by Catanzariti et al., 1997, and this data was integrated with the new bioevents reported in Agnini et al., 2014 for the Lutetian and Bartonian part of the succession. The biostratigraphycal analysis suggest that the age of the Modino Unit succession is comprised between Lutetian and Aquitanian. The petrographycal analysis on arenites show a change in sandstone compositions from the basal to the upper part of the sequence. This change is underlined by the significant presence of ophiolitic rock fragments (serpentinites, basalts and cherts) only in the oldest arenites of the succession (Lutetian and Rupelian). Moreover, this data suggests that the sedimentation of the lower part of the Modino Unit succession is influenced by sediment failures and submarine landslides from a proximal and intermittent source composed by oceanic crust successions. Probably this source can be localized in the Apenninic wedge. We think that the Rupelian-Chattian interval for this Unit, represents the link between the stage of dominant Apenninic sedimentation influenced by a high tectonic activity and the stage with dominant Alpine sedimentation.

Biostratigraphy and provenance data from Modino Unit Succession: new insights from the Northern Apennine inner-foredeep sequence

PANDOLFI, LUCA;
2015-01-01

Abstract

In the Northern Apennine fold and thrust belt, the post-collisional stages are characterized by the Oligocene–Pliocene progressive shortening and shifting of the foredeep basins, resulting from the eastward migration of the orogenic front toward the belt foreland represented by the Adria plate continental margin. The foredeep deposits were involved in the tectonic stack as thrust sheets detached from their substrate and overthrust by the Ligurian Units derived from the Jurassic Ligure-Piemontese oceanic basin. The Eocene-Oligocene succession of the Modino Unit (Tuscan Domain of the Northern Apennine) is composed by turbidites deposited on top of the Apenninic prism during the early collisional and postcollisional stages. The biostratigraphical, and petrographycal analysis of different stratigraphic sections of the Modino Unit Succession enables us to give a paleotectonic reconstruction of the evolution of this part of the foredeep. The use of calcareous nannofossils help us recognize most of the biostratigraphic units using the Chronostratigraphic Global Chart with the biohorizons developed for the Mediterranean region by Catanzariti et al., 1997, and this data was integrated with the new bioevents reported in Agnini et al., 2014 for the Lutetian and Bartonian part of the succession. The biostratigraphycal analysis suggest that the age of the Modino Unit succession is comprised between Lutetian and Aquitanian. The petrographycal analysis on arenites show a change in sandstone compositions from the basal to the upper part of the sequence. This change is underlined by the significant presence of ophiolitic rock fragments (serpentinites, basalts and cherts) only in the oldest arenites of the succession (Lutetian and Rupelian). Moreover, this data suggests that the sedimentation of the lower part of the Modino Unit succession is influenced by sediment failures and submarine landslides from a proximal and intermittent source composed by oceanic crust successions. Probably this source can be localized in the Apenninic wedge. We think that the Rupelian-Chattian interval for this Unit, represents the link between the stage of dominant Apenninic sedimentation influenced by a high tectonic activity and the stage with dominant Alpine sedimentation.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11568/753842
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