Neogene reorganization of spreading between the Tamayo and the Rivera fracture zone

Bathymetric and magnetic data from the mouth of the Gulf of California show an early episode of spreading between ±6 mybp and 3.5 mybp which rifted crust at the foot of the Tres Marias Islands from Baja California. Fracture zones from this episode do not offset the present East Pacific Rise (EPR). A reorganization of spreading beginning 3.5 mybp has led to the present configuration; its initiation is marked in the topography by a valley partially filled by a NS trending turbidite plain.