S. Levi et Rs. Yeats, PALEOMAGNETIC CONSTRAINTS ON THE INITIATION OF UPLIFT ON THE SANTA-SUSANA FAULT, WESTERN TRANSVERSE RANGES, CALIFORNIA, Tectonics, 12(3), 1993, pp. 688-702
The Plio-Pleistocene nonmarine Saugus Formation is widely exposed in t
he east Ventura basin and the northern San Fernando Valley, north and
south of the Santa Susana fault. In the east Ventura basin, the Saugus
is overlain by the Pacoima Formation. Magnetostratigraphy of the fine
-grained Saugus and Pacoima strata and the presence of the 0.76 Ma Bis
hop ash are used to calculate their average sedimentation rates: 0.9 k
m/m.y. in the east Ventura basin and 1.1 km/m.y. in the northern San F
ernando Valley. Extrapolation of the Saugus and Pacoima sedimentation
rates shows that they were deposited from about 2.3 to 0.5 Ma both nor
th and south of the Santa Susana fault. The shift from remote to local
ly derived clasts marks the initiation of uplift of the Santa Susana M
ountains. The extrapolated age of this boundary is about 0.7-0.6 Ma.