Outgassing of Mantle Volatiles in Compressional Tectonic Regime Away From Volcanism: The Role of Continental Delamination

In this study we discuss the occurrence of mantle-derived heat and volatiles (i.e., helium and CO 2 ) feeding hydrothermal systems in a seismically active margin between two convergent plates (African and European) without any signals of volcanism. The helium (He) isotopes clearly indicate a mantle-derived component in the outgassing volatiles. The estimated mantle-derived He fluxes are up to two to three orders of magnitude greater than those in a stable continental area. Such high He fluxes cannot be provided by a long-lasting diffusion, thereby implying a more efficient transport (i.e., advective transport through faults). He data coupled to heat-He relationship suggest the occurrence of active degassing of magmatic intrusions in this area of continental collisional. Geophysical data indicate the presence of a hot mantle wedge below the outgassing of mantle volatiles and a system of faults cutting the continental crust down to the hot mantle wedge. Here we discuss the hot mantle wedge and possible associated magmatic intrusions as the source of the mantle-derived volatiles outgassing in the region. We also assessed the output of mantle-derived CO 2 from the investigated hydrothermal basins. The possible occurrence of magma at depth as well as the geometry of the thick-skinned deformed wedge unambiguously indicates delamination processes that are related to continental subduction. Hence, we show that delamination processes can really produce magma at depth without evidences of volcanism at the surface. Finally, we have also provided the fault systems that work as a network of pathways and actively sustain the advective transfer of the mantle fluids toward the surface

The transition between the Marsili oceanic crust and the W Calabria rifted margin: rifting and drifting in the upper plate of the Ionian subduction zone

The western Calabria continental margin forms the transition between the Late Pliocene to Recent Marsili spreading center and continental Calabria. Integrating highpenetration and -resolution upper crustal seismic images with seafloor morphology, ODP well data and geological/geophysical constraints we provide a detailed reconstruction of the architecture of the distal portion of the W Calabria rifted margin and of the adjacent Marsili “oceanic” domain (Fig. 1) and develop a scheme for the Pliocene to present rifting and drifting of the upper plate of the Ionian subduction zone. Our seismic data document the presence of stretched and thinned continental crust, less than 10 Km thick into the eastern sector of the Marsili abyssal plain previously considered as floored by a three-layer oceanic crust. Thinning of the crust is associated with a numbers of 2-4 km wide tilted blocks composed of an acoustic basement and pre- and syn-rift sediments. Stretching factors between 1.1 and 1.42 (ca. 40% extension) has been obtained assuming a domino-like style of deformation. With few exceptions, the infill completely smoothes out pre-existing topography and explain the flat sea floor in the area surrounding the Marsili volcano. Extensional tectonics began in the Late (?) Pliocene – Early (?) Pleistocene times and ended at ca. 0.5 Ma resulting in the formation of ca. 70 km of “oceanic” domain with an average spreading rate between ca. 5.1 and 5.9 cm/yr. The appearance of vescicular basalts in the Marsili basin was not associated with the end of extension. The post-extensional sedimentary package has fairly constant thicknesses of ca. 350 along the entire Marsili abyssal plain. The Marsili volcano grows close to the western termination of the stretched and thinned W Calabria continental crust, in an asymmetric position with respect to the < 2 Ma Marsili Basin itself

A Jurassic-Cretaceous intraplatform basin in the Panormide Southern Tethyan margin (NW Sicily, Italy), reaveled by integrating facies and structural analyses with subsidence history

We illustrate the tectono-sedimentary evolution of a Jurassic-Cretaceous intraplatform basin in a fold and thrust belt present setting (Cala Rossa basin). Detailed stratigraphy and facies analysis of Upper Triassic-Eocene successions outcropping in the Palermo Mts (NW Sicily), integrated with structural analysis, restoration and basin analysis, led to recognize and describe into the intraplatform basin the proximal and distal depositional areas respect to the bordered carbonate platform sectors. Carbonate platform was characterized by a rimmed reef growing with progradational trends towards the basin, as suggested by the several reworked shallow-water materials interlayered into the deep-water succession. More, the occurrence of thick resedimented breccia levels into the deep-water succession suggests the time and the characters of synsedimentary tectonics occurred during the Late Jurassic. The study sections, involved in the building processes of the Sicilian fold and thrust belt, were restored in order to obtain the original width of the Cala Rossa basin, useful to reconstruct the original geometries and opening mechanisms of the basin. Basin analysis allowed reconstructing the subsidence history of three sectors with different paleobathymetry, evidencing the role exerted by tectonics in the evolution of the narrow Cala Rossa basin. In our interpretation, a transtensional dextral Lower Jurassic fault system, WNW-ESE (present-day) oriented, has activated a wedge shaped pull-apart basin. In the frame of the geodynamic evolution of the Southern Tethyan rifted continental margin, the Cala Rossa basin could have been affected by Jurassic transtensional faults related to the lateral westward motion of Africa relative to Europe

SEDIMENTARY DYNAMICS OF THE MARETTIMO CONTINENTAL SHELF AND MARETTIMO CHANNEL (EGADI ISLANDS – WESTERN MEDITERRANEAN): ANALYSIS OF DEPOSITIONAL AND EROSIONAL FEATURES.

Sedimentary dynamics of the Marettimo continental shelf and Marettimo Channel (Egadi Island – Western Mediterranean), have been unveiled based on the erosive and depositional features observed at the seafloor. Different morphologic features were recognized through side scan sonar, multibeam and high-resolution seismics, acquired in the framework of national Research Projects (CARG, GebecSud, MaGIC) carried out by the Department of Earth and Marine Science (former Department of Geology and Geodesy) of the University of Palermo. Sediment samples have been also collected and analyzed. The Egadi Islands are part of the NW Sicilian offshore, and belong to the mountain chain that connects the Sicilian chain to the Maghrebides one. The Marettimo Island represents an isolated portion of the Egadi continental shelf and is separated from the rest of the archipelago by the Marettimo Channel. Previous studies allowed to recognize different kind of sedimentary structures along the seafloor. Lo Iacono and Guillén (2008) described extensive field of subaqueous dunes (Ashley, 1990) along the Marettimo inner shelf, forming on gravelly and pebbly sediments and related to strong storm events (H:5.5 m, T: 12 s). Larger dunes have been observed in the north-western sector of the inner shelf with wavelengths ranging from 1 to 2.5 m, heights between 15 cm and 30 cm and extending laterally for hundreds of meters. Moreover in the north-eastern sector of the inner shelf, sorted bedforms have been detected at a depth of 40 m: they are characterized by a width varying between 15 m and 50 m and a length that reaches hundreds of meters. In the south-eastern sector of the Marettimo outer shelf, Colantoni et al. (1993) map two groups of sedimentary structures. In the same area, Lo Iacono (2004) recognized two-dimensional and three-dimensional subaqueous dunes. 2D dunes are found at depths between 60 and 90 m and show a wavelength variable between 15 and 50 m. 3D dunes, which are found at a depth of 80 m, are characterized by a wavelength of 30 m and a lateral extent of 50 m. Morphological evidences of a strong hydrodynamic regime come also from the morphobathymetric analysis of the Marettimo Channel, that is a 24 km long submarine valley oriented NNW-SSE, with a depth ranging from a minimum of 180 m to a maximum of 370 m and a width from 2 km to 14 km. Inside the channel, south of its narrowest point, a 180 m deep bathymetric threshold separates two areas, which deepens towards opposite directions: north-west and south. The flanks of the sector that deepens towards the NW are affected by mass-wasting features (Lo Iacono et al., 2007). The western flank of the channel, which delimits the Marettimo continental shelf, is carved by gullies, making the shelf-edge very uneven. Gullies develop to a maximum depth of 280 m and have a length of 250 m and a width of 50 m. At the bottom of the channel a linear incision 20 m deep, 400 m wide and almost 3 km long, is probably generated by erosive bottom currents. On the whole, the morpho-sedimentary structures here described reveal a strong hydrodynamic regime. The morphological and textural features of the bedforms observed on the Marettimo inner continental shelf suggest the occurrence of sporadic medium to strong storm events coming from western sectors. The morphological characteristics of the Marettimo Channel reveal the occurrence of strong bottom currents probably related to the severe interchange of water masses between the Tyrrhenian Sea and the Sicily Channel. References: Ashley, G., 1990. Journal of Sedim. Petrology 60, 160–172. Colantoni, P., Ligi, M., Morsiani, M.P., Penitenti, D., 1993. UNESCO Reports in Mar. Science 58, 93–98. Lo Iacono, C., 2004. Università di Napoli ‘‘Federico II,’’ Naples, Italy. Ph.D. Thesis, 150pp... Lo Iacono, C., Catalano, R., Agate, M., 2007. VI Conv. FIST GeoItalia, Rimini (Italy), 12-14 Sept. Lo Iacono C., Guillén J., 2008. Continental Shelf Research 28, 245–256

Ampiezza e tassi dei movimenti verticali a Capo Vaticano (Calabria occidentale,Italia) negli ultimi 20 mila anni determinati sulla base di cunei progradanti epiattaforme di abrasione.

Ampiezza e tassi dei movimenti tettonici verticali sono stati quantificati nel settore offshore di Capo Vaticano (Calabria occidentale), nell’intervallo Pleistocene superiore – Olocene, sulla base delle profondità del ciglio dei cunei progradanti infralitorali e delle piattaforme di abrasione formatesi durante l’ultimo massimo glaciale (LGM). I cunei progradanti sono stati riconosciuti in profili sismici a riflessione ad alta risoluzione Sparker. I dati sismici sono stati acquisiti lungo la piattaforma e la scarpata continentale superiore, durante le crociere oceanografiche Marisk 2010 e 2012 organizzate dall’IAMC del CNR di Napoli, il DISTEM dell’Università di Palermo e il Dip. di Scienze della Terra dell’Università di Napoli. La deformazione tettonica verticale del promontorio di Capo Vaticano e del suo prolungamento offshore è caratterizzata da una marcata asimmetria, con profondità dei cigli dei cunei infralitorali che si approfondisce progressivamente procedendo verso NE. La rimozione della componente non tettonica dei movimenti verticali, ottenuta utilizzando dati sulle variazioni glacio-eustatiche del tardo Quaternario [Lambeck et al., 2011], indica nell’area in esame ~11 (± 5) m di sollevamento e di ~25 (± 5) m di subsidenza, nell’intervallo post-LGM, muovendoci da sud-ovest verso nord-est, su una distanza di ~22 km. Il valore medio del tasso di sollevamento e di subsidenza (considerando la componente sia regionale sia locale) per gli ultimi 20.350 (± 1,35) anni sono pari a 0,52 (± 0,28) mm/anno e di 1,23 (± 0,32) mm/anno, rispettivamente. I valori dell’ampiezza e il pattern dei movimenti verticali ottenuti attraverso l’analisi dei cunei progradanti infralitorali sono comparabili, sebbene a tassi parzialmente differenti, sia con quelli determinati attraverso marker geomorfologici tardo Olocenici [Spampinato et al., 2012] che con i tassi di sollevamento a lungo termine calcolati sulla base delle posizioni dei terrazzi marini formatisi a 80 a 215 mila anni [Cucci & Tertulliani, 2010]. L’integrazione dei nuovi dati con quelli disponibili in letteratura indica che il basculamento del promontorio di Capo Vaticano è episodico ed è avvenuto principalmente tra 215 e 125 mila anni e nel post-LGM