The Loreto Basin, Baja California Sur forms part of the Gulf Extensional Province (GEP) within the Gulf of Mexico. In this basin the depositional architecture and sedimentology of a series of correlatable, well exposed deltas have been investigated (PhD Mortimer, with S.Gupta and P.A.Cowie). Their architecture, specifically a transition from shelf to Gilbert-type delta, combined with palaeoslope analyses, reveals a tectonic control on this transition. Specifically, the fault behaviour must be episodic at 10 kyr cycles. This has important implications for earthquake hazard analysis as this fault must go through episodes of more frequent or greater magnitude earthquakes at the 10 kyr frequency.
In addition, the evolution of the footwall scarp: its rate of retreat and incision through the footwall lithologies, have been investigated in conjunction with the hanging-wall basin fill (Mortimer, in collaboration with B. Carrapa). For the first time, a provenance investigation has been used to constrain the evolution of a normal fault bordering a rift system.