Chapter 11 - Subduction-Related Sedimentary Basins of the US Cordillera

Abstract

The western United States records a complex Phanerozoic history, which includes several subduction-related orogenies with associated sedimentary basins. Older basins and the history they record are overprinted by younger events, so that much of this history must be inferred. Application of actualistic plate-tectonic models for the origin and evolution of sedimentary basins results in key constraints on interpreting the paleogeography and paleotectonics of the Cordilleran region. The history of subduction-related sedimentary basins should be viewed in the temporal and regional context of Phanerozoic evolution of the western United States, including the following phases: 1. Latest Proterozoic rifting of Rodinia to form the early Paleozoic intraplate margin, along which accumulated the Cordilleran miogeocline; 2. Devonian-Mississippian Antler orogeny and proforeland basin; 3. Mississippian-Pennsylvanian intraplate margin (including Havallah basin), with possible transform and/or extensional tectonics; 4. Pennsylvanian-Permian Ancestral Rockies orogeny, an expression of intracontinental deformation resulting from terminal suturing of Gondwana to Laurasia along the Appalachian-Ouachita-Marathon orogenic belt; 5. Permian-Triassic Sonoma orogeny; 6. Triassic-Jurassic continental-margin magmatic arc and related basins; 7. Late Jurassic Nevadan orogeny formed during closure of a remnant ocean basin between colliding arcs; 8. Latest Jurassic-Late Cretaceous arc-trench system (including forearc basins), with major retroarc shortening and flexural loading to form the Cordilleran retroforeland basin during the Late Cretaceous Sevier orogeny; 9. Latest Cretaceous-Eocene Laramide orogeny, involving shortening of continental basement far inland, as rapid convergence and subduction of buoyant crust resulted in flat-slab subduction; 10. Oligocene ignimbrite flare-up, which resulted from sudden slowing of convergence between North America and the Farallon plate, and consequent collapse of the subducting slab; 11. Miocene-Holocene triple-junction migration, with attendant formation of the Basin and Range Province, Rio Grande rift, and San Andreas transform boundary. An integrated four-dimensional analysis of these diverse basins and associated terranes is necessary for a more complete understanding of the Cordillera.