AAPG Bulletin, V. 82 (1998), No. 8 (August 1998), P. 1575-1595.

Recognition of a Santonian Submarine Canyon, Great Valley Group, Sacramento Basin, California: Implications for Petroleum Exploration and Sequence Stratigraphy of Deep-Marine Strata¹

Thomas A. Williams,² Stephan A. Graham,³ and Kurt N. Constenius⁴

©Copyright 1998.  The American Association of Petroleum Geologists.  All Rights Reserved

¹Manuscript received February 10, 1997; revised manuscript received September 9, 1997; final acceptance February 25, 1998.
²Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305, and Petroleum Consultant, 827 Joost Avenue, San Francisco, California 94127.
³Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305.
⁴Department of Geosciences, University of Arizona, Tucson, Arizona 85721.

T. Williams and S. Graham thank corporate sponsors of the Stanford Program on Deep-Sea Depositional Systems (SPODDS): Exxon Production Research Company, Chevron Petroleum Technology Company, Conoco, Inc., British Petroleum, ARCO, Norsk Hydro, Texaco, JAPEX, and Elf Aquitane. T. Williams was supported in part by a fellowship provided by Phillips Petroleum. K. Constenius assembled his seismic database under support of NSF grant EAR-9317096 to Roy Johnson, University of Arizona. Seismic data for this study were provided to Williams and Graham by Conoco, Inc.; Chevron, USA, Inc.; Texaco Exploration and Production, Inc.; and GTS Corp. and to Constenius by Amoco Production Company and Shell Western Exploration and Production Company. Some of our seismic data were reprocessed by Excel Geophysical, and final versions of some data were produced with Schlumberger’s Geoquest™ system. Subsurface micropaleontologic data were provided by Exxon Company, USA. We gratefully acknowledge the following colleagues for valuable discussions and/or manuscript reviews: W. R. Dickinson, W. Galloway, R. Johnson, R. V. Ingersoll, J. C. Ingle, W. V. Sliter, E. I. Rich, I. Moxon, and R. Herrmann. 

ABSTRACT

Seismic stratigraphic and outcrop interpretation of Santonian-Campanian portions of the Great Valley group in the north-central Sacramento basin, California, reveal the presence of a large, north-south-oriented submarine canyon. Named after an overlying town, Williams canyon appears to have been cut during the middle Santonian and filled during the late Santonian and early Campanian (approximately 85-80 Ma). This fossil canyon is more than 100 km in length, ranges from 12 to 22 km in width, and contains compacted sedimentary fill with a maximum thickness of 1.5 km over its mapped extent. Williams canyon is comparable in scale to the Paleogene gorges of the Sacramento basin.

Stratigraphic relations indicate active folding locally during the Turonian-Santonian and probable structural control on the location of the canyon. Regional correlations showing uplift and regression along the northern basin margin synchronous with transgression of the eastern basin margin during canyon incision suggest that tectonic tilting of the basin initiated cutting of Williams canyon, whereas the role of eustatic sea level change appears to have been negligible.

Delineation of Williams canyon clarifies geometries of outcropping and subsurface strata because some of the canyon fill previously has been correlated to older strata, and canyon boundaries locally have been misinterpreted as faults. Over most of its areal extent, the sequence boundary associated with canyon incision is characterized by facies associations that do not conform to widely cited sequence stratigraphic models of deep-marine deposits, suggesting that such models are oversimplified. Combination trapping geometries created by Williams canyon cut-and-fill represent an untested gas exploration play.