--> ABSTRACT: The Pliocene Canyon-Perched Deltas of Ventimiglia (NW Italy), by A. Breda and D. Mellere; #90906(2001)

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A. Breda and D. Mellere

Department of Geology, Paleontology and Geophysics, University of Padova, Padova, ITA

ABSTRACT: The Pliocene Canyon-Perched Deltas of Ventimiglia (NW Italy)

The narrow Ligurian and Provençal shelf (north-western Italy and south-eastern France) is dissected by a series of deeply incised paleovalleys and related slope canyons. These features, formed during the Messinian base-level fall, were rapidly transgressed and then infilled - during Pliocene - by spectacular, coarse-grained Gilbert-deltas. The Ventimiglia paleovalley is cut entirely into Eocene turbidites. The basal erosion surface of the valley is highly irregular and paved by Lower Pliocene transgressive shales up to 180 m thick. The main valley -fill feature is an up to 500 m thick Gilbert-delta complex that progrades to the south into the canyon head. The shelf and shelf edge delta complex is conglomeratic and shows clinothems up to 150 m thick with foresets dipping 5°-15° to the southsoutheast. At least four superimposed deltaic cycles have been identified, attesting to the Pliocene high frequency cyclicity. Tectonic uplift and erosion of the Alpine hinterland controlled the steepness of the shelf – slope profile and provided the coarse-grained supply to the deltas, whereas eustatic fluctuations controlled the deltaic architecture. Highstands, falling stages and lowstands are accompanied by progradation of the conglomeratic wedges, with condensed shale intervals marking the transgressive tracts.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado