The San Remo 258-271 Sheet of the Carta Geologica d'Italia alla scala 1:50.000 (CARG Project) covers an area characterized by the occurrence of the Provençal (the Meso-Cenozoic section of the Ligurian Alps fordeep and foreland) and the Ligurian Alps nappe front units (i.e.: the Western Liguria Flysch complex). In the considered area, the Meso-Cenozoic cover consists of marls and marly-clays, Campanian in age, that are overlain by the Paleogene unit named “Nummulitique” by the French authors. This “Nummulitique” is composed of a transgressive upper Lutetian complex evolving into a Bartonian-Priabonian siliciclastic turbidite complex (Ventimiglia flysch). The lower complex includes coarse grained siliciclastic, mixed and carbonate lithofacies of shallow marine environments (Capo Mortola calcarenite) grading upwards to deep marine marls (Olivetta San Michele silty marl). In the area, the nummulitic limestone is commonly made up of larger foraminifera calcarenite and calcirudite that, from South to North, laterally grade to oncolithic limestone (Loreto calcarenite member), mainly composed of rhodoliths and Acervulina macroids. The Ventimiglia flysch can be regarded as a lateral equivalent of the french «Grès d’Annot». The sedimentation of the lower and the upper complex is controlled by the tectonic events of the Ligurian Alps. The former deposits took place during the early evolution stage of the Ligurian Alps foredeep basin, whereas the turbidite deposits of Ventimiglia flysch record the basin filling phase. Evidences of this tectonic control are provided by the occurrence in the Ventimiglia flysch of olistoliths and olistostromes supplied by the chain front, and of slumping and synsedimentary folding. The nappe front is made by the structurally highest units of the Alpine building. These are flysch units originally located in very inner sectors (the oceanic Piedmontese-Ligurian Domain) and turbidite deposits, probably representing the early foreedep sedimentation, that are tectonically interposed between the Provençal domain and the Flysch nappe. The tectonic pile is composed, top to bottom, by the following tectonic units: San Remo - Monte Saccarello (Cretaceous in age; including the San Bartolomeo formation, basin plain sediments; Bordighera sandstone, arenaceous turbidites; San Remo flysch, calcareous turbidites) and Baiardo-Triora (composed only by the Priabonian Baiardo flysch, characterized by the occurrence of olistoliths supplied by the chain front). The San Remo - Monte Saccarello Unit exhibits syn-sedimentary deformation structures, three ductile deformations (the SW-verging D1 and D2 and the NW-verging D3), and brittle-ductile shear zones.

Carta Geologica d'Italia alla scala 1:50.000 con Note Illustrative - Foglio "San Remo" n.258-271.

GIAMMARINO, STANI;DABOVE, GIAN MARIO;FRAVEGA, PATRIZIA;MORELLI D;PIAZZA, MICHELE;VANNUCCI, GRAZIA MARIA
2010

Abstract

The San Remo 258-271 Sheet of the Carta Geologica d'Italia alla scala 1:50.000 (CARG Project) covers an area characterized by the occurrence of the Provençal (the Meso-Cenozoic section of the Ligurian Alps fordeep and foreland) and the Ligurian Alps nappe front units (i.e.: the Western Liguria Flysch complex). In the considered area, the Meso-Cenozoic cover consists of marls and marly-clays, Campanian in age, that are overlain by the Paleogene unit named “Nummulitique” by the French authors. This “Nummulitique” is composed of a transgressive upper Lutetian complex evolving into a Bartonian-Priabonian siliciclastic turbidite complex (Ventimiglia flysch). The lower complex includes coarse grained siliciclastic, mixed and carbonate lithofacies of shallow marine environments (Capo Mortola calcarenite) grading upwards to deep marine marls (Olivetta San Michele silty marl). In the area, the nummulitic limestone is commonly made up of larger foraminifera calcarenite and calcirudite that, from South to North, laterally grade to oncolithic limestone (Loreto calcarenite member), mainly composed of rhodoliths and Acervulina macroids. The Ventimiglia flysch can be regarded as a lateral equivalent of the french «Grès d’Annot». The sedimentation of the lower and the upper complex is controlled by the tectonic events of the Ligurian Alps. The former deposits took place during the early evolution stage of the Ligurian Alps foredeep basin, whereas the turbidite deposits of Ventimiglia flysch record the basin filling phase. Evidences of this tectonic control are provided by the occurrence in the Ventimiglia flysch of olistoliths and olistostromes supplied by the chain front, and of slumping and synsedimentary folding. The nappe front is made by the structurally highest units of the Alpine building. These are flysch units originally located in very inner sectors (the oceanic Piedmontese-Ligurian Domain) and turbidite deposits, probably representing the early foreedep sedimentation, that are tectonically interposed between the Provençal domain and the Flysch nappe. The tectonic pile is composed, top to bottom, by the following tectonic units: San Remo - Monte Saccarello (Cretaceous in age; including the San Bartolomeo formation, basin plain sediments; Bordighera sandstone, arenaceous turbidites; San Remo flysch, calcareous turbidites) and Baiardo-Triora (composed only by the Priabonian Baiardo flysch, characterized by the occurrence of olistoliths supplied by the chain front). The San Remo - Monte Saccarello Unit exhibits syn-sedimentary deformation structures, three ductile deformations (the SW-verging D1 and D2 and the NW-verging D3), and brittle-ductile shear zones.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11567/259300
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