Southeastern Tyrrhenian Sea Research Articles

Hinterland geology and continental margin growth: the case of the Gioia Basin (southeastern Tyrrhenian Sea)

Abstract The Gioia Basin is a small trough located in the southeastern Tyrrhenian Sea between the Aeolian island arc and Sicily and Calabria. It is experiencing a post-rift margin evolution, while tectonic deformation and high rates of vertical movement are still affecting the Sicilian and Calabrian mainland. The analysis of the evolution of the post-rift depositional systems along the various sectors of the Gioia Basin margin has been carried out through the combined interpretation of multibeam bathymetry and seismic reflection data. Two seismic units have been identified and their component geomorphological elements ascertained through the analysis of seismic facies distribution. In general, the depositional architecture of the margin, the sedimentary environments and facies and related geomorphological elements that are active in the shaping of the margin appear to be mainly controlled by the physiography of the basin itself and by the geology of the hinterland that results from the structural evolution of the adjacent land areas. An evolution from a generalized slope bypass setting to a prograding offlapping slope architecture is recognized and explained as due to the transition from an out-of-grade to a graded profile progressing from the early post-rift stage to the later margin growth stage. Along the Sicilian margin, a constructional apron, mainly consisting of channel levee deposits, makes up much of the studied sedimentary package and reflects a high sediment supply related to the large size of river catchments on land. In contrast, the northeastern Sicilian basin sector is a destructional margin that flanks a region where small river drainage systems result in a low sediment supply to the basin and a continued high uplift rate promotes slope instability; as a consequence, the basin infill is here almost completely made up of mass-wasting deposits. In the Calabrian margin, a first phase of low sediment supply probably coinciding with the filling of the further inland Gioia Tauro half-graben was followed by the establishment of the Gioia-Mesima channel-canyon system that, furnishing an effective sediment flux to the margin, allows the formation of an intraslope depositional body consisting of channelized turbidite lobes.

Is there a mantle plume below Italy?

Some of the most diverse igneous rocks found on Earth occur along the length of Italy and in many of the islands in the southeastern Tyrrhenian Sea, all the result of Cenozoic magmatism. Magmas extremely rich in alkalis, particularly potassium, and many undersaturated with respect to silica, were erupted, as well as others of calc‐alkalic affinity (see legend in Figure 1).Their origin has been the subject of heated debate, and there is still no general consensus about how they formed. Most attribute them to subduction‐related processes (see Beccaluva et al. [2004] for a review); others consider them to be the result of within‐plate magmatism [e.g., Vollmer, 1976; Lauecchia and Stoppa, 1996]. Still others consider magmatism the result of a deep, mantle upwelling within a slab window coupled with mixing between isotopically different reservoirs [Gasperini et al., 2002].

Sedimentological and paleontological features of sea floor sediments of penta palummo and miseno volcanic highs, gulf of naples (south-eastern Tyrrhenian sea)

A sedimentological and paleontological study has been carried out on surficial sediments of Penta Palummo and Miseno volcanic banks, in the Gulf of Naples (South-eastern Tyrrhenian Sea). The deposits consist of bioclastic sand (coralline algae, bryozoans, gastropods, bivalvs and echinoderms). The benthic foraminiferal assemblage is mainly characterized by epiphytic species. Bioclastic sand is autochtonous and derived from breakdown of algal buildups.

Microearthquakes in the Tyrrhenian Sea as revealed by joint land and sea-bottom seismographs

Five independent ocean-bottom seismographs (OBS) were operated from 17 to 28 May, 1987 in the Southeastern Tyrrhenian Sea, at a depth range of 1000–2800 m. These were concomitantly run with nine Vesuvian Observatory and University of Calabria temporary digital seismic stations along the Calabrian coast together with fifteen permanent seismic stations in Southern Italy. The latter stations also belong to the University of Calabria, and to the Italian National Institute of Geophysics. About 200 local shocks, mainly microearthquakes ( M L < 3), were recorded by the OBS network. At least three swarms were located approximately beneath the subsea volcano Alcione (at depths of 2–7 km), beneath Diamante seamount (7–16 km), and, on land, beneath Mt. Sacro (7–10 km). Some features of the observed seismicity are typical of active volcanic areas. Up to 30 tectonic earthquakes were also located, either by the OBS array alone or by sea-bottom and land-based stations together. More than half of them occurred beneath the Tyrrhenian Sea, with the others occuring on the Apennine Peninsula. The majority of the earthquakes originated in the upper crust (1–10 km). Some concentration of shocks along the subsea slope was observed. Three shocks were located in the Benioff zone of the Calabrian arc. Some very small shocks were also distinguished in the mantle between the Benioff zone and the Moho, which may support hypotheses of deep roots (up to the asthenosphere) for volcanism in island arcs.

The Palinuro volcano and magmatism of the southeastern Tyrrhenian Sea (Mediterranean)

The Palinuro Seamount is a complex volcano located along an E-W trending, possibly strike-slip fault system extending seaward of the Calabrian Arc in the southeastern Tyrrhenian Sea. The lavas from its top are Pleistocene in age and display a marked calcalkaline affinity. Age and petrochemistry are almost identical to those of the Aeolian island arc, that have been interpreted as generated by subduction of the eastern Mediterranean beneath the Calabrian Arc. The bathyal plain between these volcanic areas is presently undergoing distension, possibly with marginal oceanization. Here, a third volcano, the Marsili Seamount, again displays in its topmost portions Pleistocene lavas with calc-alkaline affinity. In the southeastern Tyrrhenian sea calc-alkaline magmas thus seem not to be confined to the island arc system, but also characterize volcanics emplaced in apparently quite different structural settings.