Franciscan-type rocks off Monterey Bay, California: Implications for western boundary of Salinian Block

Research paper by Henry T. Mullins, David K. Nagel

Indexed on: 01 Jul '81Published on: 01 Jul '81Published in: Geo-Marine Letters


Serpentinites and spilitic basalts recovered at depths of 1000 m from Ascension Submarine Canyon northwest of Monterey Bay, California indicate that Franciscan basement is present immediately to the west of the San Gregorio Fault. This new information, together with published geological/geophysical data, support previous suggestions that the offshore western boundary of the Salinian block (Sur-Nacimiento Fault) has been tectonically truncated by the San Gregorio Fault and has been displaced by as much as 90 km to the northwest since the mid-late Miocene.