Syn-graben hidden folded structuring revealed by advanced gravity analysis: Kalaa Khesba case study (Northwestern Tunisia)

International audienceCentral Tunisia is characterized by numerous folded graben systems. In this study, the gravity data were analyzed to reveal the Syn-Graben hidden folded structuring associated with the NW-SE Kalaa Khesba graben (northwestern Tunisia). For the regional-residual separation, we adopted the Gaussian Regional/Residual Filter. This Filter was coupled with the Tilt filter to exhibit shallow sources associated with hidden folded structures toward the Kalaa Khesba graben. This method presents a new spatial filter designed to separate short-wavelength anomalies from long wavelength anomalies. After the detailed mapping of positive and negative gravity anomalies associated with respectively, anticlines and synclines, we have produced the Total Horizontal Gravity Gradient map, the Source Edge Detect (SED) map and Euler solution map to delineated the faulting network. Finally, a structural map of the Kalaa Khesba graben was achieved and compared with seismic lines analysis. In this study case, the gravity data analysis can be considered as a preferred method for structural mapping such as hidden faults and faults. The advanced processing of gravity data produces also a fine image of the subsurface geometry of a graben as well as to enable a better understand the structural complexity and the role of the various tectonic features

Syn-graben hidden folded structuring revealed by advanced gravity analysis: Kalaa Khesba case study (Northwestern Tunisia)

International audienc

Syn-graben hidden folded structuring revealed by advanced gravity analysis: Kalaa Khesba case study (Northwestern Tunisia)

International audienc

Syn-graben hidden folded structuring revealed by advanced gravity analysis: Kalaa Khesba case study (Northwestern Tunisia)

International audienceCentral Tunisia is characterized by numerous folded graben systems. In this study, the gravity data were analyzed to reveal the Syn-Graben hidden folded structuring associated with the NW-SE Kalaa Khesba graben (northwestern Tunisia). For the regional-residual separation, we adopted the Gaussian Regional/Residual Filter. This Filter was coupled with the Tilt filter to exhibit shallow sources associated with hidden folded structures toward the Kalaa Khesba graben. This method presents a new spatial filter designed to separate short-wavelength anomalies from long wavelength anomalies. After the detailed mapping of positive and negative gravity anomalies associated with respectively, anticlines and synclines, we have produced the Total Horizontal Gravity Gradient map, the Source Edge Detect (SED) map and Euler solution map to delineated the faulting network. Finally, a structural map of the Kalaa Khesba graben was achieved and compared with seismic lines analysis. In this study case, the gravity data analysis can be considered as a preferred method for structural mapping such as hidden faults and faults. The advanced processing of gravity data produces also a fine image of the subsurface geometry of a graben as well as to enable a better understand the structural complexity and the role of the various tectonic features

Syn-graben hidden folded structuring revealed by advanced gravity analysis: Kalaa Khesba case study (Northwestern Tunisia)

International audienceCentral Tunisia is characterized by numerous folded graben systems. In this study, the gravity data were analyzed to reveal the Syn-Graben hidden folded structuring associated with the NW-SE Kalaa Khesba graben (northwestern Tunisia). For the regional-residual separation, we adopted the Gaussian Regional/Residual Filter. This Filter was coupled with the Tilt filter to exhibit shallow sources associated with hidden folded structures toward the Kalaa Khesba graben. This method presents a new spatial filter designed to separate short-wavelength anomalies from long wavelength anomalies. After the detailed mapping of positive and negative gravity anomalies associated with respectively, anticlines and synclines, we have produced the Total Horizontal Gravity Gradient map, the Source Edge Detect (SED) map and Euler solution map to delineated the faulting network. Finally, a structural map of the Kalaa Khesba graben was achieved and compared with seismic lines analysis. In this study case, the gravity data analysis can be considered as a preferred method for structural mapping such as hidden faults and faults. The advanced processing of gravity data produces also a fine image of the subsurface geometry of a graben as well as to enable a better understand the structural complexity and the role of the various tectonic features

Geodynamics of the Southern Tethyan Margin in Tunisia and Maghrebian domain: new constraints from integrated geophysical study

The geodynamic evolution of the Southern Tethyan Margin of Tunisia is investigated using geophysical studies. Analysis of gravity and seismic reflection data in the Maghrebian domain and Southern Tunisia reveals the geodynamic role played by the North Saharan Flexure (NSF) in the evolution of the Southern Tethyan Margin. The Saharan Atlas Mountains (Atlasic Basin) and the African Craton (Telemzan High) are separated by the NSF which is a regional-scale feature that may represent a significant basement discontinuity that has controlled the Paleozoic, Mesozoic, and Cenozoic evolution of the Tunisian and Maghrebian Tethyan Basin

Geophysical Constraints on the Location and Nature of the North Saharan Flexure in Southern Tunisia

Gravity data, integrated with seismic refraction/reflection data, well data and geological investigations, were used to determine the location of the paleogeographic boundary between the Precambrian Saharan domain and the younger Tunisian Atlas domain. This boundary (North Saharan Flexure or NSF) has not been as clearly defined as it has been to the west in Algeria and Morocco. The gravity data analysis, which included the construction of complete Bouguer and residual gravity anomaly maps, revealed that the Atlasic domain is characterized by relative negative gravity anomalies and numerous linear gravity trends implying a thick and deformed sediment cover. The Saharan domain is characterized by relatively positive gravity anomalies with few gravity trends implying a thin and relatively undeformed sediment cover. An edge-enhancement analysis of the residual gravity anomalies revealed that the NSF is characterized by a series of discontinuous east- and northwest-trending linear anomalies south of 34°N that are not related to the well-known faults within the Gafsa and Accident de Medenine regions. Based on the continuity of the amplitudes of seismic reflection data and the trends of the residual gravity anomalies, the NSF is not an abrupt discontinuity but a series of step faults dipping toward the Atlasic domain. To obtain a more quantitative representation of the southern edge of Tunisian Atlas, a regional gravity model constrained by two wells and seismic reflection/refraction data was constructed along a north-south trending profile which confirms the presence of thicker sediments north of the NSF. Our analysis shows that the NSF has controlled the depositional environment of the sedimentary rocks within the region since at least Triassic time and has acted as a barrier to Atlasic deformation south of the NSF. The NSF is considered an important tectonic feature that has controlled the paleogeographic evolution of the southern margin of the Tethys Ocean, and it continues to be active today based on seismicity hazard studies