Abstract
The integrated analysis of high-resolution multibeam bathymetry and single-channel seismic profiles around Salina Island allowed us to characterize the stratigraphic architecture of the insular shelf. The shelf is formed by a gently-sloping erosive surface carved on the volcanic bedrock, mostly covered by sediments organized in a suite of terraced bodies, i.e. submarine depositional terraces. Based on their position on the shelf, depth range of their edge and inner geometry, different orders of terraces can be distinguished. The shallowest terrace (near-shore terrace) is a sedimentary prograding wedge, whose formation can be associated to the downward transport of sediments from the surf zone and shoreface during stormy conditions. According to the range depth of the terrace edge (i.e., 10–25 m, compatible with the estimated present-day, local storm-wave base level in the central and western Mediterranean), the formation of this wedge can be attributed to the present-day highstand. By assuming a similar genesis for the deeper terraces, mid-shelf terraces having the edge at depths of 40–50 m and 70–80 m can be attributed to the late and early stages of the Post-LGM transgression, respectively. Finally, the deepest terrace (shelf-edge terrace) has the edge at depths of 130–160 m, being thus referable to the lowstand occurred at ca. 20 ka. Based on the variability of edge depth in the different sectors, we also show how lowstand terraces can be used to provide insights on the recent vertical movements that affected Salina edifice in the last 20 ka, highlighting more generally their possible use for neo-tectonic studies elsewhere. Moreover, being these terraces associated to different paleo-sea levels, they can be used to constrain the relative age of the different erosive stages affecting shallow-water sectors.
Highlights
In the last few decades, recent advances in seafloor imagery systems enabled to extensively map the submarine flanks of volcanic islands in different geodynamic setting, revealing a large variability of landforms due to volcanic, tectonic, and erosive-depositional processes [1,2,3,4,5,6,7,8]
The integration of morpho-bathymetric data and single-channel seismic profiles allows us to reconstruct the overall stratigraphic architecture of the shelf surrounding Salina Island, with particular attention to the development of terraced prograding wedges, i.e. submarine depositional terraces. These prograding wedges lie above an erosive surface that was carved on volcanic bedrock (Figures 5 and 6) and interpreted as the result of cumulated marine erosion on the flanks of subaerial/shallow-water volcanic centres during stages of reduced or inactive volcanism over different eustatic cycles [17]
At Salina, the shelf edge is commonly at depths comparable or shallower than the maximum depth of −127 m reached by the sea level in the last 450 ka [29], even if these values are not corrected for glacio-hydro-isostatic effect), in agreement with the regional uplift that characterizes the Aeolian Islands since the Last Interglacial, as witnessed by raised terraces [26]
Summary
In the last few decades, recent advances in seafloor imagery systems enabled to extensively map the submarine flanks of volcanic islands in different geodynamic setting, revealing a large variability of landforms due to volcanic, tectonic, and erosive-depositional processes [1,2,3,4,5,6,7,8]. (a) to reconstruct the original extension of early volcanic centres in the development of the island, including deeply eroded submarine cones, with respect to subaerial main centres, and (b) to assess the vertical movements of the volcanic edifice that have occurred after the shelf formation due to erosion [13,14,15,16,17] Another geomorphological/stratigraphic marker for relative paleo-sea level reconstruction and assessment of vertical movement is the edge depth of prograding sedimentary wedges, forming morphological terraces (Submarine Depositional Terraces, SDT hereafter, [18,19,20]). A good match has been found between the depth of these terraces (commonly in the range of 15–60 m) and the upper
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