Paleobathymetric reconstruction of the Miocene "Venetian foothills" (NE Italy): a multidisciplinary approach based on foraminiferal assemblages and rhodolith facies
Abstract
A paleobathymetric reconstruction, based on the integrated study of both foraminiferal assemblages and red-algal concretions (rhodoliths), has been carried out for the Venetian Foothill succession cropping out along the southern border of the Alpine chain (Veneto-Friuli Foreland System, NE Italy). The studied succession, up to 500 m thick, has been deposited into a shallow to deep water marine environment during the Aquitanian to Langhian time-interval, due to the combined effect of the Dinaric and Alpine tectonics and the eustatic sea-level changes. The main goals of this work are: i) to reconstruct the paleobathymetry of the Venetian foothill succession and, tentatively, ii) to relate the bathymetric evolution of the studied areas to the sea-level changes and to the history of the vertical motion ("geohistory") of the underlying substratum in response to tectonics and sedimentary load. The detected time-interval (Aquitanian to Langhian) is particularly important as it embraces the transition between the Dinaric and South-Alpine orogenetic phases. The main results can be summarised as follows: a paleobathymetric evolution has been observed for the studied succession from the Aquitanian to the Langhian. In particular a 40--60 m paleodepth has been determined for the Calcareniti di Castelcucco Fm. Moreover a peculiar depositional environment, such as an outer-shelf incised by submarine canyons and characterised by a relatively high water hydrodynamism, has been proposed for this formation on the basis of the rhodolith size (5--6 cm). An upper to lower neritic depth (from 0--100 to 100--200 m) has been obtained for the Siltiti dei Casoni and Arenarie di Libano Formations and for the Marne di Monte Bolago Fm., respectively. An upper bathyal depth (200--600 m) has been determined for the lower-middle part of the Marne di Monfumo Fm. Finally a gradually decreasing in depth has been observed, in particular a lower to upper neritic paleodepth (from 200--100 to 100--0 m) has been proposed for the upper portion of the Marne di Monfumo Fm. and for the Monte Baldo Fm., respectively. This paleobathymetric evolution has also been related to the transgressive-regressive cycles and to the geohistory of the underlying substratum in response to tectonics and sedimentary load.
- Publication:
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EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA.....5211M