The offshore sector of southwestern Sicily, as represented in the Sheet 628 “Sciacca”, is part of the external segment of the Sicilian Fold-and-Thrust Belt (SFTB) and has recorded a complex geological evolution. The integration of marine geophysical data, seismic stratigraphy, and well-log interpretations has allowed for a detailed reconstruction of the 3D geological model down to a depth of 5 km, correlating tectonic structures between offshore and onshore sectors. The main stratigraphic setting of this sector consists of Meso-Cenozoic carbonate successions (Saccense domain) overlain by Neogene-Quaternary syntectonic deposits, with the Pleistocene terrigenous sediments recording the most recent tectonic deformation. The regional Neogene to Quaternary tectonic evolution of this sector of the SFTB is defined by a multistage deformation history: i) Messinian to Early Pliocene compressional event resulted in south-east vergent folds in the post-early Jurassic portion of the sedimentary succession with local decollement surfaces at different stratigraphic intervals, ii) the Late Pliocene–Early Pleistocene compressional stage generated highangle thrusts responsible for the exhumation of main carbonate reliefs and the development of the a new forward thrust system named Gela Thrust Wedge; this last was also responsible for the occurrence of structures generated by gravity processes; iii) a post-Early Pleistocene compressional-transpressional event activated major tectonic structures, including a conjugate NNE-SSW-oriented left-lateral transpressive fault (pop-up structure). This structure is recognizable in the western offshore sector (Capo San Marco). The integration of seismic-stratigraphic and structural data has provided insights into the linkage between deep and shallow geological structures. The gravimetric anomaly map reveals a NE-SW-trending positive Bouguer anomaly, consistent with subsurface tectonic features. Heat flux data confirm the relationship between deep aquifer systems within fractured Mesozoic carbonates and offshore fluid escape structures, linking the Sciacca Geothermal Field to offshore thermal anomalies. Analysis of high-resolution single channel seismic profiles provided for a detailed assessment of most recent tectonic activity, that is responsible for NNE-SSW trending high angle faults affecting the seabed, as well as pockmarks, chimneys, and gas flares, concentrated in the western and central offshore sector (Capo San Marco and Verdura River mouth, and indicating active fluid migration. These morphological features are strongly correlated with the most recent buried tectonic structures here reconstructed, providing evidence of active tectonics. Finally, the 3D geological model has delineated the extent, thickness, and fault boundaries of buried tectonic units, refining our understanding of the region’s tectonic evolution and the relationships between deep geological structures and seabed morphological features.
Offshore 3D geological model of the 628 Sheet “Sciacca” (Progetto CARG)
Rizzo G. F.
;
2025-01-01
Abstract
The offshore sector of southwestern Sicily, as represented in the Sheet 628 “Sciacca”, is part of the external segment of the Sicilian Fold-and-Thrust Belt (SFTB) and has recorded a complex geological evolution. The integration of marine geophysical data, seismic stratigraphy, and well-log interpretations has allowed for a detailed reconstruction of the 3D geological model down to a depth of 5 km, correlating tectonic structures between offshore and onshore sectors. The main stratigraphic setting of this sector consists of Meso-Cenozoic carbonate successions (Saccense domain) overlain by Neogene-Quaternary syntectonic deposits, with the Pleistocene terrigenous sediments recording the most recent tectonic deformation. The regional Neogene to Quaternary tectonic evolution of this sector of the SFTB is defined by a multistage deformation history: i) Messinian to Early Pliocene compressional event resulted in south-east vergent folds in the post-early Jurassic portion of the sedimentary succession with local decollement surfaces at different stratigraphic intervals, ii) the Late Pliocene–Early Pleistocene compressional stage generated highangle thrusts responsible for the exhumation of main carbonate reliefs and the development of the a new forward thrust system named Gela Thrust Wedge; this last was also responsible for the occurrence of structures generated by gravity processes; iii) a post-Early Pleistocene compressional-transpressional event activated major tectonic structures, including a conjugate NNE-SSW-oriented left-lateral transpressive fault (pop-up structure). This structure is recognizable in the western offshore sector (Capo San Marco). The integration of seismic-stratigraphic and structural data has provided insights into the linkage between deep and shallow geological structures. The gravimetric anomaly map reveals a NE-SW-trending positive Bouguer anomaly, consistent with subsurface tectonic features. Heat flux data confirm the relationship between deep aquifer systems within fractured Mesozoic carbonates and offshore fluid escape structures, linking the Sciacca Geothermal Field to offshore thermal anomalies. Analysis of high-resolution single channel seismic profiles provided for a detailed assessment of most recent tectonic activity, that is responsible for NNE-SSW trending high angle faults affecting the seabed, as well as pockmarks, chimneys, and gas flares, concentrated in the western and central offshore sector (Capo San Marco and Verdura River mouth, and indicating active fluid migration. These morphological features are strongly correlated with the most recent buried tectonic structures here reconstructed, providing evidence of active tectonics. Finally, the 3D geological model has delineated the extent, thickness, and fault boundaries of buried tectonic units, refining our understanding of the region’s tectonic evolution and the relationships between deep geological structures and seabed morphological features.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
