Tectonic and sedimentary linkages between the Belt-Purcell basin and southwestern Laurentia during the Mesoproterozoic, ca. 1.60–1.40 Ga

Abstract

Mesoproterozoic sedimentary basins in western North America provide key constraints on pre-Rodinia craton positions and interactions along the western rifted margin of Laurentia. One such basin, the Belt-Purcell basin, extends from southern Idaho into southern British Columbia and contains a >18-km-thick succession of siliciclastic sediment deposited ca. 1.47−1.40 Ga. The ca. 1.47−1.45 Ga lower part of the succession contains abundant distinctive non-Laurentian 1.61−1.50 Ga detrital zircon populations derived from exotic cratonic sources. Contemporaneous metasedimentary successions in the southwestern United States—the Trampas and Yankee Joe basins in Arizona and New Mexico—also contain abundant 1.61−1.50 Ga detrital zircons. Similarities in depositional age and distinctive non-Laurentian detrital zircon populations suggest that both the Belt-Purcell and southwestern U.S. successions record sedimentary and tectonic linkages between western Laurentia and one or more cratons including North Australia, South Australia, and (or) East Antarctica. At ca. 1.45 Ga, both the Belt-Purcell and southwest U.S. successions underwent major sedimentological changes, with a pronounced shift to Laurentian provenance and the disappearance of 1.61−1.50 Ga detrital zircon. Upper Belt-Purcell strata contain strongly unimodal ca. 1.73 Ga detrital zircon age populations that match the detrital zircon signature of Paleoproterozoic metasedimentary rocks of the Yavapai Province to the south and southeast. We propose that the shift at ca. 1.45 Ga records the onset of orogenesis in southern Laurentia coeval with rifting along its northwestern margin. Bedrock uplift associated with orogenesis and widespread, coeval magmatism caused extensive exhumation and erosion of the Yavapai Province ca. 1.45−1.36 Ga, providing a voluminous and areally extensive sediment source—with suitable zircon ages—during upper Belt deposition. This model provides a comprehensive and integrated view of the Mesoproterozoic tectonic evolution of western Laurentia and its position within the supercontinent Columbia as it evolved into Rodinia.