Active continental rifting in southern Baja California, Mexico: Implications for plate motion partitioning and the transition to seafloor spreading in the Gulf of California

摘要: Three major earthquake series have occurred during the past 30 years on fault systems that are spatially and kinematically distinct from oceanic spreading centers transform faults in southern Gulf of California. Focal mechanism solutions for earthquakes April 1969 June 1995 indicate nearly pure normal displacement across NNW striking planes. This seismicity falls along different strands a system extends at least 300 km strike defines western limit Extensional Province. The dominant control distribution Neogene basins been active since middle to late Miocene time. Epicenters August lie south Baja California peninsula focal strike-slip displacement. seismic activity is likely related WNW continental borderland, which isolate as microplate within Pacific-North American plate boundary. Therefore, modern America motion partitioned into three systems: transforms California, margin Pacific peninsula. Kinematic partitioning required accommodate strongly dimensional strain transtensional rifting. Continental rifting seafloor overlapped time 3.6 Myr., also attributed highly oblique kinematics