The Colorado Basin direction is orthogonal to the present-day volcanic margin. The most frequent hypothesis is that the Colorado Basin is an aborted rift resulting from a previous RRR triple junction. However, we found evidences for successive extensional events with different directions to explain the Colorado Basin formation. This work presents results of a combined approach using seismic interpretation and structural, isostatic, gravimetric and thermal modelling. It highlights the structure of the crust, the subsidence and the evolution of the Argentine margin. The structural interpretation shows two main directions of faulting: margin-parallel faults (~N30°) and rift-parallel faults (~N125°). An intra syn-rift discordance locally separates wedges with different dipping directions: NE-SW in the lower wedge and NW-SE in the upper wedge. The evolution of the basin is strongly linked to inheritance and the emplacement of Lower Crustal Bodies (LCBs). Modelled high density LCBs allow to reproduce the gravimetric signal as well as the temperature measured in the wells down to 4500 m. They show two directions corresponding to the trends of faults and depocentres. The calculated thermal conductive field is in accordance with the measured temperatures for conductivities and heat productions characteristic of either high degree metamorphic rocks or mafic magmatic bodies intruded at the base of the crust. We thus propose that the two successive extensions are accompanied by magma supply, which is emplaced (1) in the thinnest crust below the NW-SE depocentres, then (2) along the major NE-SW fault scarp as well as below the volcanic seaward dipping reflectors.