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

Abstract

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.

Validation of empirical source-to-sink scaling relationships in a continental-scale system: The Gulf of Mexico basin Cenozoic record

“…General paleoclimate data were derived from the website http:// www .scotese .com /climate .htm. Recent provenance analysis using detrital zircons, which to a great degree is also a test of method, has largely supported the catchment interpretations for the Paleocene-Eocene Wilcox, Oligocene, and Lower Miocene intervals (Mackey et al, 2012;Craddock and Kylander-Clark, 2013;Blum and Pecha, 2014;Xu et al, 2016;Bush et al, 2016). Channel-belt scaling, an empirical approach to drainage basin estimation, also confirms the Lower Miocene catchment reconstructions (Xu et al, 2017).…”

“…3D). Drainage reorganization was also accompanied by growth of the Laramide deformation front which increased precipitation (Sewall and Sloan, 2006;Bush et al, 2016). These longer rivers, larger catch-ments, and greater discharge generated the sediment load that ultimately formed the large abyssal plain fans of the Paleogene Lower and Middle Wilcox Group (Zarra, 2007).…”

Detrital Zircon Geochronology of Upper Cretaceous to Paleocene Sandstones From South‐Central Wyoming: Evidence for Middle Campanian Laramide Deformation

“…The proposed middle Campanian onset of Precambrian basement‐cored (Laramide) uplift, based on detrital zircon evidence, is earlier than many previous studies suggest (Bush et al, ;Cather et al, ; Chapin & Cather, , ; Dickinson et al, ; Gries, ; Lowell & Gries, ). However, some earlier studies suggest that Laramide deformation began locally as early as the early (Reynolds, ) to middle Cretaceous (Merewether & Cobban, ; Schwartz & DeCelles, ; Steidtmann & Middleton, ).…”

“…Initiation and development of the Precambrian basement‐cored uplifts throughout the Rocky Mountain region were not synchronous, and the onset, duration, and magnitude of uplift, as well as timing of the new drainage patterns established during the overlap of the Sevier and Laramide orogenies, remain controversial (Bush et al, ; Cather et al, ; Chapin & Cather, , ; Dickinson et al, ; Fan & Carrapa, ; Gries, ; Lowell & Gries, ; Merewether & Cobban, ; Reynolds, ; Rudolph & Saylor, ; Schwartz & DeCelles, ; Steidtmann & Middleton, ; Stevens et al, ). Recently, U‐Pb detrital zircon geochronology has been successfully used to document continental‐scale sediment dispersal patterns (Dickinson & Gehrels, , ; LaMaskin, ) and link synorogenic strata to specific orogenic wedge structures in the North American Cordillera (Dickinson & Gehrels, ; Fuentes et al, ; Gehrels & Dickinson, ; Lawton & Bradford, ).…”

Detrital zircon microtextures and U‐PB geochronology of Upper Jurassic to Paleocene strata in the distal North American Cordillera foreland basin

“…Blatt [] wrote that “The most important problem in the interpretation of the micropetrology of sandstones is the evaluation of the abundance of detritus of first‐cycle as opposed to polycyclic origin.” Even with the advent of multiple new provenance techniques since that time, most studies today are still hampered by this fundamental limitation. Much previous work has suggested that sediment recycling in the NA Cordilleran foreland basin is extensive [ Dickinson and Gehrels , , , ; Leier and Gehrels , ; Laskowski et al ., ; Painter et al ., ; Bush et al ., ]. However, detrital zircon U‐Pb dating is ubiquitous among these studies, and a major difficulty associated with detrital zircons is that they are very robust and can remain intact for several sedimentary cycles.…”