Publication Date:
2016-09-03
Description:
New geochronological constraints on upper crustal exhumation in the southern Rocky Mountains help delineate the latest Cretaceous–Paleogene history of drainage reorganization and landscape evolution during Laramide flat-slab subduction beneath western North America. Detrital zircon U-Pb data from the Raton basin of southern Colorado and northern New Mexico define the inception of coarse-grained siliciclastic sedimentation and a distinctive shift in provenance, from distal to proximal sources, that recorded shortening-related uplift and unroofing along the Laramide deformation front of the northern Sangre de Cristo mountains. This Maastrichtian–early Paleocene (~70-65 Ma) change—from distal foreland accumulation of siliciclastic sediment derived from the thin-skinned Cordilleran (Sevier) fold-thrust belt to deposition of coarse-grained sediment proximal to a Laramide basement block uplift—reflects eastward deformation advance and reorganization of drainage systems that supplied large-volume Paleocene–lower Eocene deposits to the Gulf of Mexico. The timing of unroofing along the eastern deformation front is synchronous with basement-involved deformation across the interior of the Laramide province, suggesting abrupt wholesale uplift rather than a systematic inboard advance of deformation. The growth and infilling of broken foreland basins within the Laramide interior and at its margins had a major impact on continental-scale drainage systems, as the ponded/axial Laramide basins trapped large volumes of sediment and reorganized major source-to-sink sediment pathways.
Print ISSN:
0278-7407
Electronic ISSN:
1944-9194
Topics:
Geosciences
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