Detrital record of initial basement exhumation along the Laramide deformation front, southern Rocky Mountains

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• 作者：Meredith A. Bush ; Brian K. Horton ; Michael A. Murphy ; Daniel F. Stockli
• 刊名：Tectonics
• 出版年：2016
• 出版时间：September 2016
• 年：2016
• 卷：35
• 期：9
• 页码：2117-2130
• 全文大小：2.1MB
• ISSN：1944-9194

文摘

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 results for 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 sediment derived from the thin-skinned Cordilleran (Sevier) fold-thrust belt to coarse-grained sedimentation proximal to a Laramide basement block uplift—reflects cratonward (eastward) deformation advance and reorganization of drainage systems that supplied a large volume of Paleocene–lower Eocene sediments to the Gulf of Mexico. The timing of unroofing along the eastern deformation front is synchronous with basement-involved shortening 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 interior and margins of the Laramide province had a significant impact on continental-scale drainage systems, as several ponded/axial Laramide basins trapped large volumes of sediment and induced reorganization of major source-to-sink sediment pathways.