The Palos Verdes anticlinorium along the Los Angeles, California coast: Implications for underlying thrust faulting

The Palos Verdes anticlinorium (PVA) is a 70 km-wide, NW-trending Pliocene-Quaternary transpressional high that separates the onshore Los Angeles basin from the offshore San Pedro basin. The PVA southwest limb underlies a 70 km-long SW facing seafloor escarpment. This escarpment is separated into two segments by a 6 km right step. It overlies two levels of NE dipping low-angle thrust faults. These faults project beneath Los Angeles toward known SW verging blind thrust faults and may be the same regional faults. These conclusions are based on a detailed geometric representation constructed from a regional analysis of 5000 km of multichannel seismic reflection profiles, logs, and paleontology from 19 wells, published seafloor geology, and multibeam bathymetric data. Patterns of sedimentation and erosion indicate that folding of PVA initiated during Pliocene time and propagated southward, with folding of part of the southern PVA occurring during the Quaternary. Structural relief continues to grow with regional long-term rock uplift of the PVA crest and ongoing subsidence in the adjacent basins. The low-angle NE-dipping faults beneath the PVA must be late Quaternary active in order to maintain hanging wall rock uplift above subsiding footwalls. Structural geometry requires that the underlying faults have slipped at 1.1-1.6 mm/yr over Quaternary time.