Regional overview of Cretaceous paleogeography of western North America
Cretaceous rocks are widespread along the Pacific margin of North America and record the presence of various plutonic, metamorphic, and volcanic events, basin types, depositional systems, and tectonic regimes. More accurate time-stratigraphic divisions of Cretaceous rocks, based on improved biostratigraphic zonations and new radiometric dating, permit both improved paleogeographic and reconstructions and correlations with changes in global sea level, climate, and oceanic paleocirculation patterns. Better understanding of the mobility and interaction of tectono-stratigraphic terranes along the Pacific margin, supported by paleomagnetic studies of increased accuracy, have forced us to reevaluate all previous paleotectonic and paleogeographic reconstructions. Major accretionary events, marked by regional structural deformation, metamorphism, and plutonism, characterized the Pacific margin in the Jurassic. The Cretaceous paleogeographic framework, in general, reflects the reconstruction of the margin into a more continuous and less complex magmatic arc, forearc basin, and subduction complex. The Paleogene was marked by renewed disruption, translation, dispersion, and accretion in most areas. Active Cretaceous magmatic belts were present, from south to north, in the Mojave Desert, Sierra Nevada, Idaho batholith, North Cascades, Coast plutonic complex, and Alaska Range. Cretaceous plutonic belts in the Salinian block, Transverse Ranges, and Peninsular Ranges of Alta and Baja California formed far south of their present locations and did not accrete until the Paleogene. Forearc basins west and south of the magmatic arcs were widespread and generally characterized by thick sequences of turbidites.
- Research Organization:
- RPI Pacific, Inc., Redwood City, CA
- OSTI ID:
- 5067161
- Report Number(s):
- CONF-8608105-
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Vol. 70:7; Conference: 4. circum-Pacific energy and mineral resource conference, Singapore, China, 17 Aug 1986
- Country of Publication:
- United States
- Language:
- English
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