Gravity constraints on the underground structural framework and associated volcanism of the Maghrebian allochthonous domain: The Sejnene Numidian flysch, Tunisian Tell

• The work proposed tectonic framework model for Numidian flysch of Tunisia.
• Gravity processing highlights unknown deep structuring and associated lineaments.
• NE-, NW-, E- and N- striking faults subdivide the area into differential sub-basins.
• Neogene NW- then N- striking stresses induced rejuvenation of inherited faults.
• Conjugate strike slip movements induced rising of synkinematic volcanic rocks.

Tectonic framework of the Neogene Numidian flysch is one of the primary subjects in the Tell of northern Tunisia for understanding the late Miocene kinematics around the Mediterranean Basin. Belonging to the extreme North of Tunisia, this domain is marked by a confuse structuring. Much of the Sejnene area is represented by thick Neogene Numidian flysch, which is widely exhibited around the Mediterranean and directly deposited on Mesozoic and Cenozoic strata.Gravity measurements covering the Sejnene area coupled with geological outcropping data were used to constrain the deep structural setting of the Neogene Numidian flysch and its associated volcanic outcrops. Integration of different gravity processed maps, leads us to highlight relationship between outcropping and sealed deformed structures and proposed a tectonic framework model for raised volcanic rock within the thrust sheet system. Maps resulted from gravity processing reveal structural variations marked by several geometries and oriented lineaments. This structuring suggests that the Sejnene study area is marked by two tectonic framework domains: to the North, the areas is mainly characterized by NE- and E- oriented subparallel lineaments corresponding to thrusts, reverse faults and strike slip reverse fault system. Conversely to the South, the same master trends are crossed by others NW- and N- trending transversal and deep-seated lineaments corresponding to strike slip reverse faults.Neogene NW- then N- striking compressional phases have induced inversion of inherited structures that are fossilized by rejuvenation of ancient faults affecting the basement. The final obtained structural setting suggests South-verging evolution of the Numidian domain under low-angle decollement layer to the North and under deep-seated thrusting and strike slip movements to the South. Master strike slip movements induced rising of lithospheric volcanic rocks.Geophysical and geological study of the Sejnene area provides a new insight into tectonic framework of the Numidian flysch and the associated Mogods volcanic rocks. Structuring of this Tellian domain well correlated with orogenic episodes of the western Mediterranean and seems to be related to the Alpine orogeny.