California coast range tectonics in light of geophysical constraints: A tribute to Ben Page

The central and southern Coast Ranges, extending from the San Francisco Bay area 400 km south-eastward to the Transverse Ranges, form part of a wide, soft plate boundary between the Pacific plate and the Sierra Nevada subplat e, a boundary that was inherited from the Mesozoic Franciscan subduction pr ism. Cutting diagonally through the Coast Ranges from their west side on th e north to their east aide on the south, the San Andreas strike-slip fault system accommodates more than 90% of the relative plate motion; the remaini ng small component, convergence normal to the fault, produced Miocene-prese nt intense folding, reverse faulting, and, finally, the present ranges. A r epresentative crustal cross section at the latitude of San Francisco Bay di splays these structures along with the geophysical evidence. Structures now juxtaposed across the Sail Andreas system were transported through restric ting and releasing bends in the complex fault system, but regionally the ce ntral and southern Coast Ranges exhibit areal contraction of at least 20%.