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The Tyrrhenian Basin is a sedimentary basin located in the eastern Mediterranean Sea. It is bounded by Sardinia to the west, Corsica to the northwest, Sicily to the southeast, and Italy to the northeast.
Regional Geologic Setting
The Tyrrhenian Basin is a back-arc basin formed from the northwest subduction of the African plate beneath the Eurasian plate. It trends roughly northwest-southeast and contains two sub-basins - the Vavilov and Marsili basins.
Stratigraphy
Basement Structure
Tyrrhenian basement rocks consist of late Paleozoic granites derived from the Hercynian orogeny.[1] Basement rocks in the southeastern portion of the basin were reactivated during the Alpine orogeny while those to the northwest were undisturbed.[1]
Upper Sardinia Margin
The Upper Sardinia Margin is a fault-bounded passive margin to the northwest of the Vavilov Basin. Seismic reflection surveys across the Upper Sardinia Margin exhibit a stratigraphic geometry suggestive of pre-rift, syn-rift, and post-rift sequences.[2] Drill cores penetrating to the base of the syn-rift sediments identified a transgressive sequence related to subsidence of the continental crust during the rifting stage of the Tyrrhenian Basin opening.[2] At the base of the syn-rift sequence is 60 meters of Tortonian conglomerate with subrounded clasts derived from metamorphosed carbonate and quartzitic basement.[2] It is inferred that this conglomerate formation was deposited in a high-energy subaerial environment like an alluvial fan. Overlying the conglomerate formation are oyster-bearing glauconitic sandstones deposited in a nearshore environment.[2] Late Tortonian to Early Messinian calcareous ooze and claystone with benthic foram assemblages overlays the sandstone formation; this indicates that water depth increased,[2] perhaps due to subsidence at the end of the syn-rift period. The boundary between the syn-rift and post-rift periods is believed to be located in a 50 meter section of late Messinian gypsum that overlays the calcareous ooze and claystone formations. At the top of the stratigraphic section is a 243-meter-thick section of Pliocene to Pleistocene post-rift sediment containing calcareous mud with occasional terrigenous clastics and volcanic ash.[2]
Vavilov Basin
The basement stratigraphy in the Vavilov Basin consists of strongly serpentinized peridotite with both high and low-temperature phases of deformation. The peridotite is overlain by 120 meters of tholeiitic pillow basalt with carbonate-filled veins. Nannofossils and planktonic foraminifera within the carbonate veins constrain the age of emplacement between 3.1-3.6 Ma.[2] Immediately above the basalt is a 100 meter-thick section of Pleistocene sedimentary cover, consisting primarily of nannofossil-rich mud with occasional reworked volcanogenic debris[2].
Marsili Basin
Basin Development
References
- ^ a b Sartori; et al. (2001). "Neogene evolution of the southwestern Tyrrhenian Sea (Sardinia Basin and western Bathyal plain)". Marine Geology. 175: 47–66. doi:10.1016/S0025-3227(01)00116-5.
{{cite journal}}:|access-date=requires|url=(help); Explicit use of et al. in:|last1=(help) - ^ a b c d e f g h Kastens, K. and Mascle, J. (1988). "ODP Leg 107 in the Tyrrhenian Sea: Insights into passive margin and back-arc basin evolution". Geological Society of America Bulletin. 100 (7): 1140–1156. Retrieved 16 February 2015.
{{cite journal}}: CS1 maint: multiple names: authors list (link)
- ^ Sartori, R. (2003). "The Tyrrhenian back-arc basin and subduction of the Ionian lithosphere" (PDF). Episodes. 26 (3): 217–221. Retrieved 16 February 2015.