3D Modelling of Late Quaternary coastal evolution between Albenga and Loano (Western Liguria, Italy)

Figures & data

Figure 1. Geographical setting of the study area. (a) Schematic map of the Ligurian Sea and location of the study area. (b) Bathymetric map of the study area derived from the EMODnet data (Fiorentino et al., 2021) with the location of the seismic lines. Black lines: Sub Bottom profiles (SBP); Red lines: Boomer seismic lines.

(a) Schematic draw of Italy with enlightened the extension of the NW of the Regione Liguria with the location of the main towns along the coastline (East to West: Genova, Savona, Albenga and Ventimiglia).and the target area of this study, which is presented in Fig 1(b). (.b) bathymetry of the study area with the location map of the seismic lines and of the profiles showed in the figures (East to West: La Spezia, Genova, Savona, Albenga, Ventimiglia and Nice) with bathymetry.

Figure 2. (a) thickness (in meters) of the TRF seismic unit (seismic wave velocity of 1650 m/sec TWTT), corresponding to the Holocene Lutites. (b) Morpho-bathymetric map of the study area showing the location of the shelf-break and the three heads of Albenga, Ceriale and Loano Canyons.

(a) Thickness map of the TRF seismic unit. (.b) Bathymetric map of the study area with shaded relief of the areas covered by seismic profiles.

Figure 3. Seismo-stratigraphic architecture of the shelf area in front of Albenga and summary of the identified seismo-stratigraphic units and surfaces of the late Quaternary sequence. The acronyms with their corresponding chrono-stratigraphic units from literature are also indicated. (a) Boomer line 2007–4 showing the thick Plio-Pleistocene deposits buried by the HARF deposits (mainly gravels and sands) and the recent HST deposits (constituted by fine-grained sands and muds). (b) detail of Boomer line 2007–4 highlighting the internal architectures of the Late Quaternary sequence. It is visible, in detail, the retrogressive overlap pattern of the high-amplitude reflective subunits (respectively: TST1-5) and the presence of a buried, very high-amplitude subunits (BHARF) at the base of the transgressive unit.

(a) Boomer seismic line across the shelf area with interpretation and indication of the units, subunits and reflectors identified. (.b) magnification of the seismic line of the Fig 3(a) highlighting the seismo-stratigrafic architecture of the transgressive unit and subunits.

Figure 4. (a) Seismic Boomer line 2007–9 showing the seismo-stratigraphic units TRF, TST3, and their separating surface THARF calibration based on Vibracore C10 data sampling. (b) Vibra-core sampling log reconstruction and a related photo image of coarse littoral sediments (sands and gravels) of the transgressive TST3 subunits and muddy offshore deposits of the TRF unit, corresponding with the Transgressive Systems Tract (TST) and High Stand Systems Tract (HST), respectively.

(a) Boomer seismic line showing the position of the vibracore C10 used for the stratigraphic calibration of the TRF and HARF units. (.b) detailed stratigraphy of the Vibracore C10 data and picture of the core.

Figure 5. (a) Seismic SBP line 29 showing the common terraced-like arrangement of the HARF Sub-units deposits (TST1-5). (b) Three-dimensional view of the SBP lines showing the high lateral continuity of the HARF subunits highlighted by the high amplitude reflection facies and the terraced arrangement.

(a) Sub Bottom Profile interpretation showing the terraced arrangement of the transgressive subunits TST1-5. (.b) three-dimensional view of Sub Bottom Profile showing high the lateral continuity of the HARF subunits.

Figure 6. (a) Seismic SBP line 14 (trace in Figure 1(b)) showing the features of the TST subunits in the shelf area along the Monte Croce High. (b) Seismic Boomer line 2007–26 showing the Plio-Pleistocene morphostructural high outcropping in the outer shelf area bounded by a fault zone with NW dip. Green and orange dashed lines indicate the main Plio-Pleistocene reflectors.

(a) Seismic SBP line showing the features of the TST subunits in the shelf area along the Monte Croce High. (.b) Seismic Boomer line showing the Plio-Pleistocene morpho-structural high outcropping in the outer shelf.

Figure 7. (a) Seismic SBP line 11 shows the accumulation features of the TST1 subunit in the outer shelf area, consisting of symmetrical, high-reflective ridges with troughs filled with less reflective deposits. (c) Seismic SBP line 38 showing a thickness of the TRF unit minimal, or absent, while the THARF reflector is generally more irregular associated with small depressions and sub-outcropping reliefs. (b) and (d) Insets of the TST subunits distribution map with the location of the seismic lines.

(a) image of a Sub Bottom Profiler seismic line SBP11 which enlightens the position of the transgressive deposits and the occurrence of buried littoral dunes produced during the TST1 stage. (.b) Extract of the main map with the distribution of the transgressive deposits together with the trace of analysed seismic lines. (c) Image of a Sub Bottom Profiler seismic line SBP38 which enlightens the position of the thick delta-conoid deposits produced by the Centa River. Also, other transgressive deposits are shown. (d) extract of the main map with the distribution of the transgressive deposits, of the Centa rivers delta conoids together with the trace of the analysed seismic lines.

Figure 8. Palaeo-environmental reconstruction of the evolution of the coastal areas between Albenga and Loano since the Last Glacial Maximum. The evolutions steps TST 1, TST2, TST3, TST4 and TST5 were reconstructed based on the distribution of the transgressive deposits TST and their paleo-morphologies.

Maps showing the stepwise evolution of the coastline of the study area from stage TST1 to stage TST5. Main watercourses, paleoenvironmental elements and location of present-day towns are also indicated. Lands in grey colour, sea in light blue.

Fiorentino, A., Battaglini, L., & D’Angelo, S. (2021). EMODnet collation of geological events data provides evidence of their mutual relationships and connections with underlying geology: A few examples from Italian seas. Quarterly Journal of Engineering Geology and Hydrogeology, 54(1), 2019–2147. doi:10.1144/qjegh2019-147

 Web of Science ®Google Scholar