Analogue models of basins affected by differential deformation in extensional and compressional regimes Jara, Pamela 1,2 ; Likerman, Jeremías 3,4 ; Cristallini, Ernesto 3,4 , Ghiglione, Matías 3,5 , Pinto, Luisa 1 , Reynaldo Charrier 1 and Jara, Carlos 1 . 1 Departamento de Geología, FCFM, Universidad de Chile, Plaza Ercilla 803, Casilla 13518, Correo 21, Santiago, Chile. 2 Departamento de Ingeniería en Minas, Universidad de Santiago de Chile (USACH). Av. Libertador Bernardo O`Higgins 3363. Santiago, Chile 3 Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Avda. Rivadavia 1917, CP C1033AAJ, Ciudad de Buenos Aires, Argentina. 4 Laboratorio de Modelado Geológico (LaMoGe), Instituto de Estudios Andinos Don Pablo Groeber. Universidad de Buenos Aires, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina. 5 Laboratorio de Tectónica Andina, Instituto de Estudios Andinos Don Pablo Groeber, Universidad de Buenos Aires. Departamento de Ciencias Geológicas, Buenos Aires. Argentina. *Contact email: pajara@ing.uchile.cl Abstract. We performed a series of analogous experiments with different geometric configuration that permit us to simulate differential deformation applied in an inverted basin. These models, allow us to discern between the resulting geometries according to the stress and the degree of deformation analyzed. These results will be useful to recognize the processes that may occur during the evolution of natural cases of inverted basins to generate the resulting geometry, both in plan and profile. Keywords: analogous experiments, inverted basin, differential deformation. 1 Introduction As is well known, the developments of rift basins is associated with an extensional regime and are prone to reactivate previous anisotropies or lithospheric weakness. The evolution along the entire basin may be heterogeneous and segmentation producing sub-basins is common. These sub-basins can display sedimentary and structural differences. Furthermore, the subsequent inversion of these extensional systems can produce a reactivation of preexisting normal faults (Cooper and Williams, 1989) and different trending contractional structures could coexist. Previous analogue models have been performed to study the tectonic inversion and compare the resulted geometries depending on the inherited characteristics of the extensional system (McClay, 1995; Amilibia et al., 2005; Yagupsky et al., 2008). In this contribution, we performed a series of models using combinations of differential or homogeneous extension within a region and its subsequent inversion, which could be affected by homogeneous or differential compression. Five analogue experiments were carried out to reproduce the simplest scenarios to discriminate the resulting geometries, both in cross section and in plan view, and then link them to the different processes to which the deposits were subjected. 2 Experimental setting The experiments were carried out in the LaMoGe (Laboratorio de Modelado Geológico), Universidad de Buenos Aires, Argentina. All of them were built-up in a 70cm x 50cm x 3cm deformation rig. Layers of well sorted dry quartz sand with well rounded grains smaller than 500 μm were used, stained in order to generate different colors for the subsequent observation of the layers in profile. A thin basal layer of silicone, selected to simulate stretching at the base of the brittle upper crust, was prepared according to the necessary shape and disposition for each experiment. The movement, during both the extensional and compressional phases, was done by a stepper motor, anchored to a mobile backstop wall properly prepared to be used with homogeneous or differential movements (Fig. 1); this wall was attached to a basal plate that only moves during extensional experiences, to generate extensional movement below the silicon layer. The resulting differential deformation was progressive and performed by pivot rotation of the backstop wall. This axis support that generates the pivot rotation, can be released to generate homogeneous movement, which allowed the combinations necessary to compare the results according to the processes generated: i) extensional differential deformation, ii) compressional differential deformation, iii) differential extension and homogeneous compression, iv) homogeneous extension and differential compression, and finally, v) extension and subsequently compression, both differentials. 302