Evidence for triassic salt tectonics in the meridional tellian Atlas: Example from the Ouled H'daïm diapir, Northern-central Algeria

The Ouled H'daïm diapir, located in the southern Tellian Zone, provides new insights into the role of salt tectonics in the structural evolution of the region. This study challenges the hypothesis that the Triassic outcrop was emplaced by thrusting and instead favors a diapiric emplacement. Field investigations reveal a vertical ascension of the Triassic body during extensional phases, followed by lateral migration within the Santonian basin, which persisted from the Santonian to at least the Paleogene. The Santonian-Triassic contact exhibits several geological features that confirm diapiric activity.

Fracture analysis highlights the inheritance of basement faults, which played a key role in the evolution of the diapir, fluid circulation, and mineralization processes. Intense fracturing facilitated the formation of salt springs and iron-rich mineralized deposits, emphasiz ing the continuous interaction between tectonics and surface processes. During the Miocene, the Triassic salt material acted as a detachment surface, enabling the thrusting of allochthonous Tellian nappes.

The Ouled H'daïm diapir represents a key example of salt tectonics in the southern Tellian Zone and serves as a crucial case study for understanding diapir evolution in an Alpine compressional setting. This study highlights the need for complementary geophysical investigations to refine regional deformation models related to salt tectonics.