The Oligo-Miocene Northern Apennines evolution is characterized by the migration of the foredeep-belt-system related to the eastward progressive retreat of the Adria lithosphere. The Late Oligocene-Miocene turbidite deposits are represented by the Macigno Fm., the Modino Unit, the Cervarola Succession and the Marnoso-Arenacea Fm. This sediments are the infilling sequence of the Apenninic foredeep basin, located at the front of Northern Apennines thrust and fold belt. The aim of this work is a detailed correlation between the different stratigraphic sections of the Modino Unit, cropping out along the transect of Tuscan-Emilian region in order to propose a possible paleotectonic scenario of this area at the Oligo-Miocene boundary . The three sections analyzed in this work are: Monte Modino section, Le Tagliole-Borra section, both cropping-out in the province of Modena, and the Monte Cisa section, cropping-out in the Reggio-Emilia province. This study was carried out using a high resolution stratigraphy, a modal analysis on arenites and a biostratigraphycal analysis by calcareous nannofossils assemblage. The succession of the Modino Unit shows an overall thickening and coarsening upward trend characterized by a basal clayey-marly lithofacies made up of fine- to medium-grained arenites that correspond to the Fiumalbo Shale (Auctt). In the central part this Unit is characterized by a thin-bedded marly lithofacies interfingered (in the Monte Modino section) with different levels of breccias, corresponding to the Marmoreto Marls (Auctt). Finally, the upper sequence is characterized by thin bedded turbidites from fine to medium grained arenites, grade upward to thick bedded medium- to coarse-grained arenites. This part corresponds to the Monte Modino Sandstones Fm. Auctt. The calcareous nannofossils assemblage indicates that the age of this sequences is Lutetian and Chattian, (biozone MNP15-MNN1d of Catanzariti et al., 1997). The modal analysis on arenites shows an high percentage of metamorphic lithic fragments derived from an alpine source area (in agreement with data of Di Giulio, 1999 and Van de Kamp & Leake, 1995), but the percentage of unmetamorphic serpentinitic fragments, associated with non-metamorphic radiolarites, suggests the presence of different source areas in the arenites of Fiumalbo Shale (Sassolera Sandstones Member of Chicchi & Plesi, 1991), respect to the Monte Modino Sandstones Fm.

High resolution stratigraphy, petrography and biostratigraphy of Modino Unit (Northern Apennines, Italy): preliminary results.

MARCHI, ALESSANDRA;PANDOLFI, LUCA
2013

Abstract

The Oligo-Miocene Northern Apennines evolution is characterized by the migration of the foredeep-belt-system related to the eastward progressive retreat of the Adria lithosphere. The Late Oligocene-Miocene turbidite deposits are represented by the Macigno Fm., the Modino Unit, the Cervarola Succession and the Marnoso-Arenacea Fm. This sediments are the infilling sequence of the Apenninic foredeep basin, located at the front of Northern Apennines thrust and fold belt. The aim of this work is a detailed correlation between the different stratigraphic sections of the Modino Unit, cropping out along the transect of Tuscan-Emilian region in order to propose a possible paleotectonic scenario of this area at the Oligo-Miocene boundary . The three sections analyzed in this work are: Monte Modino section, Le Tagliole-Borra section, both cropping-out in the province of Modena, and the Monte Cisa section, cropping-out in the Reggio-Emilia province. This study was carried out using a high resolution stratigraphy, a modal analysis on arenites and a biostratigraphycal analysis by calcareous nannofossils assemblage. The succession of the Modino Unit shows an overall thickening and coarsening upward trend characterized by a basal clayey-marly lithofacies made up of fine- to medium-grained arenites that correspond to the Fiumalbo Shale (Auctt). In the central part this Unit is characterized by a thin-bedded marly lithofacies interfingered (in the Monte Modino section) with different levels of breccias, corresponding to the Marmoreto Marls (Auctt). Finally, the upper sequence is characterized by thin bedded turbidites from fine to medium grained arenites, grade upward to thick bedded medium- to coarse-grained arenites. This part corresponds to the Monte Modino Sandstones Fm. Auctt. The calcareous nannofossils assemblage indicates that the age of this sequences is Lutetian and Chattian, (biozone MNP15-MNN1d of Catanzariti et al., 1997). The modal analysis on arenites shows an high percentage of metamorphic lithic fragments derived from an alpine source area (in agreement with data of Di Giulio, 1999 and Van de Kamp & Leake, 1995), but the percentage of unmetamorphic serpentinitic fragments, associated with non-metamorphic radiolarites, suggests the presence of different source areas in the arenites of Fiumalbo Shale (Sassolera Sandstones Member of Chicchi & Plesi, 1991), respect to the Monte Modino Sandstones Fm.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11568/261738
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