Print this pageAbstract: Strain Partitioning Along the San Gregorio Fault Zone, San Mateo County, California
Jeffrey M. Nolan, Erik K. Zinn, Gerald E. Weber
Recent mapping along the San Gregorio fault zone near Point Ano Nuevo, San Mateo County, California reveals clear partitioning of strain between northwest trending thrust faults and north-northwest trending strike slip faults. Pure strike slip motion on a set of N15W to N25W trending faults is indicated by lateral offset of stream drainages and Late Quaternary and Holocene age strand lines at a loosely constrained slip rate of 4 to 10 mm/yr. Thrust faults branch westerly from the strike slip faults with trends ranging from N30W to N50W. All observed thrust faults dip northeast and show significant offset of late Quaternary features.
The observed pattern of faulting suggests that at least some of the apparent strike slip motion is due to crustal shortening across reverse faults on the southwest block. Such movement is analogous to observed deformation on the northeast side of the fault in the Santa Lucia Mountains, 100 km to the south.
AAPG Search and Discovery Article #90958©1995 AAPG Pacific Section Meeting, San Francisco, California