Major faults, salt structures and paleo-ridge at tectonic nodes in Northern Tunisia: contribution of tectonics and gravity analysis

Abstract

Structural analysis, fault kinematics, detailed geological mapping and gravity analysis provide a new approach regarding to the tectonic-model of the Bazina-Aouana structure (North-Eastern Tunisia). They show that the Bazina Triassic outcrops, such as several other structures, are related to the NE and E trending major faults junction, controlling its halokinesis, and pouring out to the NW of tectonic nodes in the collapsed compartment. During the Eocene and Tortonian compressive phases, the Triassic materials previously forming a intumescence in the NE and E major faults intersection have acted as a barrier on which collided the Aouana structure. Therefore, this structure is blocked between overthrust nappes and the Bazina paleo-ridge forming an imbricated zone overlapping the Triassic materials. This paper aims to present a new evolutionary geodynamic model for the Bazina-Aouana structure related to the tectonic node easing the Triassic salt mobilization, the paleo-ridge formation and the development of a collapsed zone. By comparing with previous works, this model is likely applicable to the important Triassic outcrops of Northern Tunisia.

Analysis of the Geological Controls and Kinematics of the Chgega Landslide (Mateur, Tunisia) Exploiting Photogrammetry and InSAR Technologies

“…The Chgega landslide occurs within the horsetail splay zone of one of the Alia-Thibar fault segments, corresponding to the Dhkila dextral fault [15] (Figure 2). In addition to the Dhkila fault, the region of Chgega Mountain is well known for the presence of an imbricate fold and thrust stack that involves mostly the Tertiary Atlassic sedimentary cover [31,[40][41][42] that is overprinted by late Miocene half-grabens [32,43]. One of the normal faults forming these half-grabens determines the Chgega landslide, as we shall see.…”

Late Miocene Extensional Collapse of Northern Tunisia

“…For this work we have compiled a raster map of northern Tunisia based on the existing 1:50.000 maps published by Officine National de Mines (Alouani et al, ; Batik, ; Biely et al, ; El Ghali et al, ; Fournet et al, ; Lamos, , ; Melki et al, ; Rouvier, , ) although, using a thorough revision and reinterpretation of the nature of the contacts between units and in some cases we have remapped or included data from Marzougui et al (; Figure ). For aiding in the structural interpretation of the region, we have divided the mapped rocks into four tectonostratigraphic units that from top to bottom are as follows: (A) Neogene to Quaternary post‐nappe sediments, tectonic breccias, and volcanic rocks; (B) Oligocene Numidian Flysch nappe.…”

“…Geological map and hanging‐wall transport sense of extensional faults in the region of Bazina‐Mateur. Modified from Marzougui et al (). Included is a lower‐hemisphere stereographic projection of fault data in the region.…”

“…The westernmost segment of the GE‐LANF has been traditionally interpreted as a thrust surface, representing the Numidian thrust front that superposes the Numidian unit over para‐autochthonous Paleogene sediments (e.g., Essid et al, ; Khomsi et al, ; Marzougui et al, ). This contact must have been originally a thrust surface when the Numidian nappe was emplaced towards the SE over the African passive margin in the Early Miocene (Belayouni et al, ; Khomsi et al, ).…”

Late Cretaceous and Palaeocene clays of the northern Tunisia: potential use for manufacturing clay products

“…From structural geology viewpoint, the area of Bir M'Cherga belongs to the field of the northern Atlas of Tunisia; it consists of a series of anticlines affected by NE-SW submeridian faults (Jauzein 1967;Zargouni 1975) which in turn cut by major E-W faults (Burolet 1956;Ben Ayed 1993;Boukadi 1994;Marzougui et al 2014;Aridhi et al 2014) and associated with grabens orthogonal to collapsed folds (Solignac 1927;Castany 1954;Ben Ayed 1993;Turki 1985;Chihi 1995;Chikhaoui 2002). This region is characterized by tectonic phenomena in compliance with the relevant tectonic framework of Tunisia.…”