Abstract: Applications of Plate Tectonics to Petroleum Geology Along Pacific Margin of North America

William R. Dickinson, Stephan A. Graham, Raymond V. Ingersoll, Teresa E. Jordan

Plate tectonics offers a coherent conceptual framework for the classification of sedimentary basins and for analyses of their bathymetric and geothermal evolution. Different kinds of plate interactions produce distinctive basin configurations and arrays of associated tectonic elements. The Cordilleran continental margin of western North America has evolved through four main phases of development: (1) rifted margin of Atlantic type in the late Precambrian and early Paleozoic; (2) Japanese-type margin with offshore island arcs and marginal seas in the late Paleozoic and early Mesozoic; (3) Andean-type margin with subduction zone at the continental edge in the late Mesozoic and early Cenozoic; and (4) Californian-type margin with transform faults along and near the continent l edge in the late Cenozoic. Most petroleum prospects in the coastal region are related to the last two settings. Principal basins of interest along Andean-type margins are forearc basins in the arc-trench gap between the belt of strong deformation in the subduction complex and the belt of igneous activity along the magmatic arc. Regional tilt downward toward the arc and low heat flux are characteristic of forearc basins. Principal basins of interest along Californian-type margins are pull-apart, fault-wedge, and fault-warp basins related to curving and braided transform-fault systems. Rapid initial subsidence and high heat flux that decays with time are characteristic of pull-apart features. All the basin types noted may develop either turbidite or deltaic reservoir systems connected to marine source beds deposited at or below the oxygen-minimum zone in thick stratal successions. Asymmetric foreland basins with regional tilt of continental basement downward toward orogens form by partial subduction of continental crust inland from magmatic arcs or adjacent to suture belts during crustal collision. These basins are marked by clastic wedges shed from the adjacent orogen.

AAPG Search and Discovery Article #90976©1976 AAPG-SEPM-SEG Pacific Section Meeting, San Francisco, California