The Southern San Joaquin Valley as an Example of Cenozoic Basin Evolution in California
- Raymond A. Price
Published Online: 18 MAR 2013
Copyright 1989 by the American Geophysical Union
Origin and Evolution of Sedimentary Basins and Their Energy and Mineral Resources
How to Cite
Goodman, E. D., Malin, P. E., Ambos, E. L. and Crowell, J. C. (1989) The Southern San Joaquin Valley as an Example of Cenozoic Basin Evolution in California, in Origin and Evolution of Sedimentary Basins and Their Energy and Mineral Resources (ed R. A. Price), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM048p0087
- Published Online: 18 MAR 2013
- Published Print: 1 JAN 1989
Print ISBN: 9780875904528
Online ISBN: 9781118666654
- Sedimentary basins—Congresses;
- Mines and mineral resources—Congresses;
- Power resources—Congresses
The Tejon Embayment and the crystalline Tehachapi Mountains are located within a rotated crustal block that lies between the San Andreas, White Wolf and Garlock faults. The area's variable tectonic history includes the origin and evolution of the Cenozoic southern San Joaquin Basin and is currently being studied using CALCRUST and industrial seismic reflection and refraction data, borehole data and field observations. The complex structure and the stratigraphy of the Tejon Embayment (Eocene to Recent) provide evidence for a sequence of very different tectonic events, including regional extension and compression.
A graben system of many small blocks was produced in the central Tejon Embayment by presently NE-trending normal faults, episodically active from late Oligocene to latest Miocene time, and by the Springs fault, which shows evidence of strike-slip. Thickness and facies changes across the normal faults reflect the deepening of the Embayment in mid-Miocene time. The normal faults were again reactivated late in the Miocene.
Evidence for late Oligocene-Early Miocene extension in the southern San Joaquin Valley includes normal faults, volcanic extrusives, coarse breccias and basic dikes. The origin of this basin and coincident regional extension may be related to the pre-San Andreas transform history of North American-Pacific plate interaction or, alternatively, to western Basin and Range extension.
At present, the U-shaped Tejon Embayment is closing from three directions. Cross sections and mapping show that a system of mostly buried Pliocene to Recent thrust faults (a) consistently verge basinward along the basin margin, (b) have displaced both the Cretaceous crystalline basement rocks and younger sedimentary rocks, (c) structurally overlie the buried normal faults, and (d) are associated both with petroliferous folds and (e) with vertical and overturned beds south of the exposed Pleito fault. Comanche Point (to the northeast) and Wheeler Ridge (to the northwest) are anticlines whose underlying thrusts are related to the basin-margin thrusts, ratherthan to the higher-angle White Wolf fault.
During rapid uplift over the past several million years, the thrusts have exhumed normal faults and volcanic rocks along the basin margin. They are part of a regional change in deformation from extension to contraction that can be related to post-Miocene transpression along the nearby San Andreas and Garlock faults, or perhaps to the continual clockwise rotation of the Tehachapi Block.
The White Wolf fault was probably tilted and segmented during this reorganization of stress regimes, accentuating the structural relief across its plane. Latest Miocene to Recent strata are more than 2500 m thicker north of the fault in the 12km-deep Maricopa subbasin than they are in the Tejon Embayment. This fact and the young compressional features on the southern and western margins of the southern San Joaquin Basin suggest that the Miocene extensional basin has evolved into a foreland-type depression.
Our deep reflection and refraction data and velocity model suggest that the Tehachapi Block is comprised of north-dipping, relatively-high velocity layers with major discontinuities at the White Wolf fault to the north and at the Garlock fault to the south. The apparent continuity of the deep structure suggests that, as the basins formed, the Neogene clockwise rotations of the Tehachapi Block may have been accommodated by detachment faults in the middle crust.