GSA Annual Meeting in Phoenix, Arizona, USA - 2019

Paper No. 82-7
Presentation Time: 9:55 AM


JONES III, James V., U.S. Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK 99508

Proterozoic sedimentary basins in western North America provide key constraints on the tectonic evolution of southwestern Laurentia and on pre-Rodinia craton interactions. The age, provenance, regional correlation, and tectonic setting of these basins are best assessed by integrating geologic mapping with geochronologic data from associated igneous bodies, metamorphic minerals, and detrital zircon. Along a north–south transect across Paleoproterozoic accreted terranes in Colorado and New Mexico, metasedimentary successions record multiple cycles of basins that formed between ca. 1.78 to 1.60 Ga. Basin formation closely followed regional deformation and metamorphic events that are older in the north and younger to the south. Metasedimentary protoliths were locally derived in most areas, but quartzites within many successions are also compositionally mature. The southward progression of younger basin ages is consistent with regional tectonic models for the evolution of the Paleoproterozoic accretionary provinces. The association of basin formation with orogenic pulses suggests that basin formation and collapse were important processes in the tectonic evolution of the continent. Mesoproterozoic sedimentary basins formed within the older accretionary provinces and help to constrain a ca. 1.45 Ga orogenic cycle in New Mexico and Arizona. The Picuris orogeny (northern New Mexico and beyond) involved tectonic burial, regional metamorphism, plutonism, and ductile deformation of ca. 1.49–1.45 Ga metasedimentary rocks. Mesoproterozoic successions are in apparent conformable contact with Paleoproterozoic strata in many localities, raising questions about the extent and importance of older orogenic events. Circa 1.50 to 1.45 Ga metasedimentary rocks exposed discontinuously from Arizona to western Canada contain ca. 1.60–1.49 Ga non-Laurentian detrital zircon that were derived from formerly adjacent cratons such as Australia. Non-Laurentian detrital zircon disappear from Belt basin and southwestern U.S. strata beginning ca. 1.45 Ga, corresponding to the onset of the Picuris orogeny in the southwest that was coeval with rifting along its western margin. In short, ca. 1.8–1.4 Ga basins provide sensitive and somewhat unique records of the Proterozoic tectonic evolution of western North America.