Abstract: Listric Normal Faults in the Plio-Pleistocene Section at the Coles Levee Oil Fields: A Response to Post-Pliocene Growth of the Elk Hills Anticline

Christopher L. Jones, Janice M. Gillespie

A subsurface study of the Plio-Pleistocene Etchegoin, San Joaquin and Tulare Formations in the North and South Coles Levee Field indicates the presence of listric normal faults which affect markers as young as the Pleistocene Basal Tulare but do not affect the section below the Etchegoin Formation. These faults control the location of gas accumulations within the Pliocene section at both the North and South Coles Levee Fields. These fields lie on the eastern end of the Elk Hills Anticline in the southern San Joaquin Valley near Bakersfield, California.

The amount of displacement along these faults within the Pliocene and early Pleistocene section is as much as 350 feet and decreases away from the crests of the Coles Levee anticlines. The larger displacements occur on east-dipping, synthetic faults. West-dipping, antithetic faults are also present, but generally have smaller displacements. The angle of dip and the amount of displacement along the faults decreases downward within the Pliocene section and the faults sole into a shallow, east-dipping detachment surface near the base of the Etchegoin Formation.

The geometry of these faults is similar to that of growth faults, however the amount of displacement along these faults does not decrease upwards in the Pliocene section, suggesting that the displacement occurred after Pliocene deposition. We believe that faulting was not caused by sediment loading on a dipping sub-stratum as with conventional growth faults, but rather by gravity-induced sliding of a thick, relatively unconsolidated sedimentary section down the steep, east-plunging end of the rapidly rising Elk Hills Anticline.

AAPG Search and Discovery Article #90958©1995 AAPG Pacific Section Meeting, San Francisco, California