The Friulian-Venetian Basin I: architecture and sediment flux into a shared foreland basin

Giovanni Toscani (1), Andrea Marchesini (2), Chiara Barbieri (3), Andrea Di Giulio (1), Roberto Fantoni (3), Nicoletta Mancin (1) & Adriano Zanferrari (2)
(1) Dipartimento di Scienze della Terra e dell'Ambiente, Università di Pavia, Italy.
(2) Dipartimento di Chimica, Fisica e Ambiente, Università di Udine, Italy.
(3) Eni S.p.A., Exploration and Production Division, San Donato Milanese, Italy.

The Friulian-Venetian Basin is a foreland basin shared by three thrust belts during the Cenozoic (External Dinarides, eastern Southern Alps and Northern Apennines). A complex sequence of tectonic and sedimentary events took place in this basin through time due to this setting. Based on a large dataset of seismic reflection profiles and well logs we reconstructed the complex succession of these events that created accommodation space (tectonic processes) and filled it (sedimentary processes). To do this we carried out eleven regional transects, and traced five basin-scale key stratigraphic surfaces that depict the general architecture of the basin and help in describing its main evolutionary steps. Each surface underwent the effects of one or more tectonic events recorded by different amount and direction of flexure. The five isobaths maps, together with the present-day topography, bound five stratigraphic intervals described through isopach maps. The joint analysis of isobaths and isopach maps highlights tectonic phases, related to thrust-belt activity, creating the accommodation space and its sedimentary fill derived from the erosion of either the same belt or older belts. Through decompaction of the volume of the sediment intervals bounded by the mapped basin-scale key-surfaces, the detrital flux through time was estimated. Starting from the low values (111 km3/My) during the Dinaric-driven cycle, the flux increases during the Southalpine-driven cycles (366 km3/My), but strongly increases reaching its maximum (2110 km3/My) during Calabrian-Holocene time, characterized by low tectonic activity. This supports the idea that climate variability is by far more efficient than tectonics in promoting erosion of mountain belts.

foreland basin, Flexural effects, Sediment flux, NE Italy.