Active extensional faulting and sedimentation are linked during basin evolution because tectonics controls the creation of the accommodation space, the sediment supply and the variation of the rate between subsidence and sedimentation. Depositional sequence mapping is a powerful technique that assists the interpretation of basin evolution on continental margins. By contrast, the detailed geometry and sequence of movements on the linked fault system directly controls the dip and strike development of the sedimentary fill, its facies, and the second order faulting within the sediments. The Tyrrhenian Sea is characterised by two large bathial basins (Vavilov and Marsili Basins), covered by few ten of meters of sediments, and a number of peri-Tyrrhenian basins filled by thousands of meters of clastic and/ or volcaniclastics sediments, spanning from Pliocene to Quaternary times. The stratigraphic record of these basins offers the opportunity to study the timing and kinematics of the basin-forming faults. Since the development of the peri-Tyrrhenian basins is genetically linked to the formation of the Tyrrhenian Sea back-arc basin the knowledge of the kinematics of the fault bounded basins is relevant for the building of a model of opening for the Tyrrhenian Sea. The geologic evolution of the Eastern Tyrrhenian Sea Continental Margin between the 42° and the 38° N parallel (from Campania to Calabria margins) has been reconstructed on the basis of a large amount of multichannel and single-channel seismic reflection data (ca. 5500 km of profiles) with different resolution and penetration, exploration wells, core data and onshore data. We interpreted this seismic grid using a seismic and sequence stratigraphy approach in a dedicated GIS environment and generated: isochron maps, 2-D models of relevant geological surfaces and 3-D digital models linking stratigraphic horizons and faults. The stratigraphy of these basins clearly records a poly-phased history of subsidence. Each episode of basin formation gives rise to a distinctive stratigraphic signature and to tectonically-enhanced sequence boundaries. In this paper we describe the depositional responses to episodic tectonic events. The Eastern pery-Tyrrhenian basins are genetically linked to the opening of the Tyrrhenian sea backarc basin, but they have indipendent stratigraphies due to different fault patterns and subsidence histories and sediment supply. The analysis of the stratigraphic record of Calabria margin, the southernmost and deepest basin, permitted to recognize several tectonic stages, each one characterized by a change in tectonic style and sedimentation. The subsidence of this area began in the Serravallian-Tortonian, but the major basin subsidence occurred in the Pliocene-Lower Pleistocene and was successively affected by transcurrent tectonic events. The Campania Margin features several sedimentary basins affected by three extensional events. The oldest extensional event occurs during the Upper Pliocene-Lower Pleistocene, whereas the youngest one occurred in the southern part of the Campania margin over the last 400 ky. In this study we emphasized intermediate scale unconformity-bounded sequences that are capable of record the basin responses to more subtle changes in extensional subsidence and structural styles. The reconstructed tectono-sedimentary evolution of the Eastern pery-Tyrrhenian basins can integrate our knowledge of the Tyrrhenian Sea crustal fabric and dynamics, plate kinematics, and timing of back-arc opening.
|Titolo:||Tectono-sedimentary processes in the Eastern Continental Margin of the Tyrrhenian Sea|
|Data di pubblicazione:||2012|
|Appare nelle tipologie:||4.2 Abstract in Atti di convegno|