ANALOGUE MODELS OF THE SOUTHERN PART OF THE GULF OF CALIFORNIA RIFT

The fault pattern observed in the southern part of the Gulf of California rift (GoC) has been simulated by a series of purely mechanical and lithospheric scale physical experiments. Model materials represent an idealized 3-layer cold lithosphere consisting of brittle and ductile crust and lithosperic mantle floating above the astenospheric mantle. In order to localize rifting and reproduce the deformation patterns of the transform plate boundary, a band of weaker model lithosphere with a zig-zag geometry was built in the corresponding zone of the model. The models were deformed in a single phase of oblique divergence and the results reproduce satisfactorily the structural patterns observed in the offshore part of the GoC. However, the onshore boundary faults of the Gulf Extensional Province were not formed in the experiments suggesting the possibility of a previous and wider episode of rifting. Similarities between the model and nature include: (1) localization of extensional deformation along basins with an favorable orientation with respect to the general displacement of the Baja California block; (2) westward migration of the depocenters and; (3) topographic asymmetry of the continental borders. The experimental results also illustrate that changes in style along the rift were probably controlled by pre-existing structural fabric.