Analogue modeling of salt tectonics associated to compressive environments and transverse zones in the axial zone of the Cordillera Oriental, Colombia

Sedimentary sequences containing evaporitic levels exhibit complex three-dimensional structures due to halokinetic movements known as salt tectonics. In the Anticlinal de Zipaquira, located in the Cordillera Oriental of Colombia, saline levels are reported within the Lower Cretaceous units. This study conducted a structural analysis of the evolution of the Anticlinal de Zipaquira, based on analogue models that simulate the relationship between salt tectonics and the transverse zones that bound and segment this structure. The models were constructed on a sandbox-type deformation table, maintaining a constant displacement velocity. The models simulate basement anisotropies using a rigid wooden block consisting of two frontal ramps inclined at 30(degrees) connected by a lateral ramp. Adjacent to this block, a layer of non-newtonian fluid and variable-colored fine quartz sand layers were arranged. Three configurations were implemented with different distributions of the non-newtonian fluid layer: A) thin continuous, B) discontinuous, and C) thick continuous. At least 15 experiments were conducted for each configuration. The results of the analogue modeling showed that the salt body in the core of the anticline is cut by reverse faults, forming a parallel salt sheet structure to the stratification. The observed structures, such as salt pillows, salt glaciers, salt sheets, and salt tongues, indicate compressive structural styles of intermediate to high maturity. The discontinuous model proved to be the most coherent since the lateral ramp did not exhibit evaporitic levels, aligning with observations in nature. The Neusa transverse Fault was represented by the lateral ramp in the model, explaining the localization of saline levels in the southern zone of the Anticlinal de Zipaquira. Finally, the evolution of the models revealed clock-wise rotations near the lateral ramp, consistent with the reported patterns of clockwise rotations in the axial zone of the Cordillera Oriental.