The Tyrrhenian back－arc basin and subduction of the Ionian lithosphere

A deep, narrow, and distorted Benioff zone, plunging from the Ionian Sea towards the southern Tyrrhenian basin, is the remnant of a long and eastward migrating subduction of eastern Mediterranean lithosphere. From Oligocene to Recent, subduction generated the Western Mediterranean and the Tyrrhenian back-arc basins, as well as an accretionary wedge constituting the SouthernAoenninic Arc.In the Tyrrhenian Sea, stretching started in late Miocene and eventually produced two small oceanic areas: the Vavilov Plain during Pliocene (in the centralsector) and the Marsili Plain during Quaternary (in the southeastern sector). They are separated by a thicker crustal sector, called the Issel Bridge. Back-arc exten-sion was rapid and discontinuous, and affected a land locked area where continental elements of various sizesoccurred. Discontinuities in extension were mirrored bychanges in nature of the lithosphere scraped off to form the Southern Apenninic Arc. Part of the tectonic units of the southern Apennines, accreted into the wedge from late Miocene to Pliocene, had originally been laid down on thinned conti-nental lithosphere, which should constitute the deep portion of the present slab. After Plio-cene, only Ionian oceanic lithosphere wassubducted, because the large buoyancy of thewide and not thinned continental lithosphere of Apulia and Africa (Sicily) preserved the seelements from roll back of subduction. After Pliocene, the passively retreating oceanic slabhad to adjust and distort according to the geometry of these continental elements.The late onset of arc volcanism in respect to the duration of extension in the Tyrrhenian-Ionian system may find an expla-nation considering an initial stage of subduc-tion of thinned continental lithosphere. The strong Pleistocene vertical movements that occurred in the whole southeastern system(subsidence in the back-arc basin and upliftin the orogenic arc) may instead be related to the distortion of the oceanic slab.

Phytoplankton Communities in a Coastal Site of Natural Reserve “Lake of Tarsia-Mouth of River Crati”-Northern Ionian Sea, Calabria (Italy)

Our work was aimed to study the phytoplankton communities in two coastal sites placed in Natural Reserve “Lake of Tarsia-Mouth of river Crati” in Northern Ionian Sea-Calabria (Italy). This zone represents a wetland area of high natural interest populated by different organisms (animals and plants) living in a transitional ecosystem characterized by a great biodiversity. The sampling was performed in two different seasonal periods (summer and autumn 2012) and in two different sites (marine site vs fluvial one). Different algal genera/species were recognized and analyzed by Utermohl inverted microscope method and also qualitative and quantitative measures of biomass were performed. The results showed that the dominant group was the Diatoms with exclusive species in such periods in both the sampling sites;we also observed the presence of genera and/or species of potentially toxic algae (Pseudo-nitzschia sp., Alexandrium taylori, Prorocentrum micans, Skeletonema sp.), mostly in summer. Complessively, the phytoplankton biomass was always higher in marine site than in the fluvial site. The results were also processed considering the context of the chemical-physical parameters (such as temperature, pH, salinity, nutrients). The high concentration of the nutrients N and P in such periods indicated a state of meso-eutrophic waters both in the proximity of river site as well as in the marine zone. The data represent the first contribution to the knowledge of the phytoplankton structure in this area, which results in a very variable environment with a high recovery capacity.

Trace metals in <i>Posidonia oceanica</i>in a coastal area of the Ionian Sea (Calabria, Italy)

As, Cd, Cu and Pb concentrations were measured in Posidonia oceanica sampled from meadows located in two sites along the calabrian coast (Ionian Sea, South-eastern Mediterranean). By dating the scales and the rhizome using retrospective procedures (lepidochronology), a time series over a period of nine years (1995-2004) was analysed. Throughout the whole lepidochronological period, the arsenic content in the scales was tenfold higher than that measured in the rhizome with a peak in the lepidochronological year 1996-1997 and a general decrease in the years after. Pb concentration also showed a tendency to decrease with time, whereas the Cd and Cu concentration were increasing. A comparison of the metal level in dead sheaths (scales) and living tissue (leaves) was also performed. The detailed distribution of the trace metals along the leaf axis and in the leaves at different developmental stages (adult, intermediate and juvenile) showed some differences in the metal content. The results also indicate that the arsenic content measured in the leaf blade reflects the high As content measured at the superficial sediments at one of the two sampled sites, demonstrating, for the first time, that P. oceanica would be a good indicator for this element.

New ideas on the tectonic of the Kurveleshi anticlinal belt in Albania, and the perspective for exploration in its subthrust

The external thrustbelt of Albania consists of some tectonic zones(Ionian,Kruja and Krasta-Cukali zones),that are westward overthrust,with a large amplitude(50e100 km),above the Apulian platform and South Adriatic Basin.The relative movement of the Adriatico-Apulian sub-plate between,the Euro Asiatic and African plates during from the Mesozoic to the Tertiary period,mainly controlled the tectonic evolution of the Albanides.The Ionian zone consists of anticline belts(Berati,Kurveleshi and Cika),that are overthrust toward the west with an amplitude about 20e30 km Their overthrustings was realized through regional sliding evaporitic horizons,which caused the masking of folded structures in the subthrust,with the perspective plays.The Kurveleshi anticlinal belt represents a mega-anticlinal with a length of 210 km and a width of about 20 km,and it is characterized by anticline structures with heterogeneous dimensions,predominantly those of great dimensions and linear type.The overthrusting of the anticline units has a local character,and it is more developed in the Kurveleshi anticlinal belt.Its magnitude is about 8e10 km.As a result of these overthrusts,imbrication and duplex styles are formed,leadind to the masking of the subthrust complex with structures of large interest(e.g.Delvina,Karbunara,etc.)where two oil fields have been dioscovered beneath the Mali Gjere anticline(Delvina oil field)and the Kremenara anticline(Karbunara oil field).Backthrust faults phenomena are secondary and they taken place in the post-collision stage.Generally they are easterward thrust faults of structural units with an amplitude of 5e10 km.The Kurveleshi anticlinal belt,based on tectonic features,is divided into two parts:The southern part,from Qafa Sevaster in the north down to Greece to the south.and northern part,from Qafa Sevaster in the south up to the end of the Patos-Verbas structure.In the southern part these features predominate:The anticline structures are large in size,and overthrust with a large amplitude(8e10 km)westward.The evaporitic diapirs have erupted through local faults of the anticline structures of the Kurveleshi anticlinal belt(Mali Gjere,Kurveleshi and Fterra anticlines).These eruptions(Delvina,Picar-Kapariel-Bashaj,etc.)have helped in the overthrusting of these structural units.It must be mentioned that the backthrusting is also affected by the diapir action.Moreover,vertical diapir occur,in the center of the structures like Navarica.In the northern part,the anticline structures are generally small to medium in size.Only the Patos-Verbas anticline is larger in size.In the Kurveleshi anticlinal belt the Ballsh and Visoka oilfields have developed.The eastern flank of the Shushica synclinal belt apears folded,and the carbonate anticline structures have developed.Existing oil fields include the Gorisht-Kocul,Cakran-Moallaj-Kreshpan and Amonica.These oil fields shoud continue towards the north(under the overthrust of the Patos-Verbas antcline)and in the south(under the regional ovethrust of the Kuervelesh anticlinal belt).