The Portofino Conglomerate (Eastern Liguria, Northern Italy): Provenance, Age and Geodynamic Implications

The Portofino Conglomerate (PC) cropping out in the Eastern Liguria is an approximately 500 m thick, very gently folded succession mainly composed of poorly bedded and mostly matrix-supported conglomerates. It stratigraphically rests on Helminthoid Flysch (UA3) thrusted onto Antola Unit. We vertically distinguished three ruditic litho/petrofacies: (i) Paraggi (fP) with carbonate clasts from succession; (ii) Monte Pallone (fMP) prevailing meta-carbonate minor quartz-rich (meta)siliciclastic high-pressure–low-pressure (HP-LP) metabasite clasts; (iii) Bocche (fMB) dominant (meta)siliciclastic, clasts, granitoid elements medium-temperature–high-temperature (MT-HT) regional metamorphic rocks. middle-upper Eocen age litho/petrofacies constrained by well-preserved microforaminifers (e.g., Globigerinatheka) recovered matrix. During its sedimentation, directions paleocurrents would indicate that PC underwent a counterclockwise rotation coeval first Cenozoic rotational phase Sardinia–Corsica system (50–30 Ma) then stopped before sedimentation litho/petrofacies. vertical compositional variation sedimentary inputs suggested result progressive deepening erosional level tectonic pile can be located Ligurian Alps Chain. considered as likely apical part submarine fan deposited piggy-back/thrust-top basin within Alpine nappe stack. This body was later tectonically transported eastward UA3 substrate (similarly to Epiligurian Units Northern Apennines) Apenninic orogenic (i.e., Unit).