During Pleistocene, transtensional to extensional faulting affected the axial sector of the Southern Apennines fold and thrust belt, allowing the formation of NW-trending fault-related intermontane basins, filled by continental Quaternary deposits (Giano et al., 2000). Among them, the High Agri Valley (HAV) has a great importance, due to the presence of natural resources. The Quaternary clastic infill of the HAV (Carbone & Giano, 2015) was formed during the activity of two main systems of NW-trending basin-bounding faults: the East Agri Fault System to the NE and Monti della Maddalena Fault System to the SW. With the aim to better understand the geometry of the clastic infill succession of the HAV, the study was focused on the realisation of a 3D static model in MOVE©, based on the acquisition of surface and subsurface data. Surface data, synthesised into a detailed geological map at a 1:25,000 scale, were collected in the field with the Geopaparazzi© smartphone application, and processed with the QGis© free software. Field data were combined with stratigraphic information coming from shallow wells, pre-existing Shallow and Deep Electrical Resistivity Tomographies (Colella et al., 2004; Rizzo et al., 2004), and five newly acquired (5) deep electrical resistivity investigation down to 1000 m depth. By identifying levels with different resistivity and joining them with the information of well logs, has been possible to create 15 geological cross-sections reaching about 1000 m depth. The 3D model allowed to construct in detail the bottom buried surface of the clastic infill deposits. The surface was processed to obtain an elevation map, which allowed the identification of three main depocenters and two threshold zones, partially corresponding to those already recognized by Colella et al. (2004). The difference in elevation between the bottom of clastic deposits and the surface topography allowed the creation of an isopach map, showing the depocentral areas with greater detail, reaching about 450 m of thickness. The geometry of depocenters is connected to the control played by NW-trending Quaternary faults, mainly characterized by dip-slip kinematics. The depocenters are bounded by thresholds, probably due to the activity of NE-trending transverse faults, with a possible strike-slip kinematics. In conclusion, the integration of geological mapping, the geophysical data and the analysis of shallow well logs into a static 3D model, has provided a more detailed image of the buried HAV basin, that might be useful for hydrogeological studies and the interpretation of the Quaternary evolution of the whole area. We are very grateful to Eni SpA and Shell Italia E&P for providing necessary data and authorizing their publication. We would like also to thank their technical teams for the fruitful discussions.
Multidisciplinary analyses for a 3D modeling of Quaternary clastic infill of the High Agri Valley
Rizzo E.
2023
Abstract
During Pleistocene, transtensional to extensional faulting affected the axial sector of the Southern Apennines fold and thrust belt, allowing the formation of NW-trending fault-related intermontane basins, filled by continental Quaternary deposits (Giano et al., 2000). Among them, the High Agri Valley (HAV) has a great importance, due to the presence of natural resources. The Quaternary clastic infill of the HAV (Carbone & Giano, 2015) was formed during the activity of two main systems of NW-trending basin-bounding faults: the East Agri Fault System to the NE and Monti della Maddalena Fault System to the SW. With the aim to better understand the geometry of the clastic infill succession of the HAV, the study was focused on the realisation of a 3D static model in MOVE©, based on the acquisition of surface and subsurface data. Surface data, synthesised into a detailed geological map at a 1:25,000 scale, were collected in the field with the Geopaparazzi© smartphone application, and processed with the QGis© free software. Field data were combined with stratigraphic information coming from shallow wells, pre-existing Shallow and Deep Electrical Resistivity Tomographies (Colella et al., 2004; Rizzo et al., 2004), and five newly acquired (5) deep electrical resistivity investigation down to 1000 m depth. By identifying levels with different resistivity and joining them with the information of well logs, has been possible to create 15 geological cross-sections reaching about 1000 m depth. The 3D model allowed to construct in detail the bottom buried surface of the clastic infill deposits. The surface was processed to obtain an elevation map, which allowed the identification of three main depocenters and two threshold zones, partially corresponding to those already recognized by Colella et al. (2004). The difference in elevation between the bottom of clastic deposits and the surface topography allowed the creation of an isopach map, showing the depocentral areas with greater detail, reaching about 450 m of thickness. The geometry of depocenters is connected to the control played by NW-trending Quaternary faults, mainly characterized by dip-slip kinematics. The depocenters are bounded by thresholds, probably due to the activity of NE-trending transverse faults, with a possible strike-slip kinematics. In conclusion, the integration of geological mapping, the geophysical data and the analysis of shallow well logs into a static 3D model, has provided a more detailed image of the buried HAV basin, that might be useful for hydrogeological studies and the interpretation of the Quaternary evolution of the whole area. We are very grateful to Eni SpA and Shell Italia E&P for providing necessary data and authorizing their publication. We would like also to thank their technical teams for the fruitful discussions.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
