Location, extent, and magnitude of dynamic topography in the Late Cretaceous Cordilleran Foreland Basin, USA: New insights from 3D flexural backstripping

Abstract

Mantle-induced dynamic topography (i.e., subsidence and uplift) has been increasingly recognized as an important process in foreland basin development. However, characterizing and distinguishing the effects (i.e., location, extent and magnitude) of dynamic topography in ancient foreland basins remains challenging because the spatio-temporal footprint of dynamic topography and flexural topography (i.e., generated by topographic loading) can overlap. This study employs 3D flexural backstripping of Upper Cretaceous strata in the central part of the North American Cordilleran foreland basin (CFB) to better quantify the effects of dynamic topography. The extensive stratigraphic database and good age control of the CFB permit the regional application of 3D flexural backstripping in this basin for the first time. Dynamic topography started to influence the development of the CFB during the late Turonian to middle Campanian (90.2-80.2 Ma) and became the dominant subsidence mechanism during the middle to late Campanian (80.2-74.6 Ma). The area influenced by >100 m dynamic subsid-ence is approximately 400 by 500 km, within which significant (>200 m) dynamic subsidence occurs in an irregular-shaped (i.e., lunate) subregion. The maximum magnitude of dynamic subsidence is 300 ± 100 m based on the 80.2-74.6 Ma tectonic subsidence maps. With the maximum magnitude of dynamic uplift being constrained to be 200-300 m, the gross amount of dynamic topography in the Late Cretaceous CFB is 500-600 m. Although the location of dynamic subsidence revealed by tectonic subsidence maps is generally consistent with isopach map trends, tectonic subsidence maps developed through 3D flexural backstripping provide more accurate constraints of the areal extent, magnitude and rate of dynamic topography (as well as flexural topography) in the CFB through the Late Cretaceous. This improved understanding of dynamic topography in the CFB is critical for refining current geodynamic models of foreland basins and understanding the surface expression of mantle processes.

Late Cretaceous Sevier Versus Laramide Orogenies in Wyoming‐Utah‐Colorado, USA: New Insights From Basin Subsidence History

“…Numerous studies on the dynamic (or residual) and tectonic subsidence in the WIB have been conducted (Li & Aschoff, 2022a, 2023; S. F. Liu, 2008; S. F. Liu et al., 2005, 2011, 2014; L. J. Liu et al., 2008; S. F. Liu & Nummedal, 2004; Painter & Carrapa, 2013; Pang & Nummedal, 1995). However, these studies primarily differentiated dynamic components from basin‐to‐mountain cross‐sections, and tectonic subsidence was back‐stripped at a stage scale with relatively low temporal resolution.…”

“…The Cretaceous North American Western Interior Basin (WIB) serves as an ideal research area for investigating basin‐forming mechanisms due to its abundant outcrop and subsurface biostratigraphic and lithostratigraphic data, as well as its extensive extent. Within this basin, different subsidence drivers have long been recognized: thin‐skinned Sevier Orogeny from the Mesozoic to the early Cenozoic, the thick‐skinned Laramide Orogeny from the Late Cretaceous to the Eocene and the Late Cretaceous long‐wavelength dynamic subsidence (Davis et al., 2022; Lawton, 2019; Li & Aschoff, 2023; S. F. Liu & Nummedal, 2004; S. F. Liu et al., 2014; Painter & Carrapa, 2013). Imbalance between relief‐generated sediment yield, deformation‐generated frontal accommodation and modest but rapidly changing eustatic sea level during Sevier and Laramide orogenies controlled the depositional architecture in the WIB.…”

“…The analysis of long‐wavelength dynamic subsidence and short‐wavelength repeated subsidence pulses, caused by mantle flow and flexural loading from the Sevier orogenic belt and Laramide uplift, has been studied (Cross, 1986; Heller & Liu, 2016; Jordan, 1981; Li & Aschoff, 2022a, 2023; S. F. Liu & Nummedal, 2004; S. F. Liu et al., 2005, 2011, 2014; Painter & Carrapa, 2013; Pang & Nummedal, 1995). However, a comprehensive analysis and discussion of the intricate relationship between these repeated short‐term subsidence pulses and the evolving architectural responses within the Sevier‐Laramide clastic wedges during basin evolution is still lacking.…”

“…However, a comprehensive analysis and discussion of the intricate relationship between these repeated short-term subsidence pulses and the evolving architectural responses within the Sevier-Laramide clastic wedges during basin evolution is still lacking. In addition, previous studies have quantitatively differentiated long-wavelength dynamic subsidence using flexural back-stripping only from cross-sectional data (S. F. Liu & Nummedal, 2004; S. F. Liu et al, 2011Liu et al, , 2014Painter & Carrapa, 2013), while tectonic subsidence reconstructions have been flexurally back-stripped by removing the sedimentary load from the basin (Li & Aschoff, 2023). The detailed variations in tectonic or dynamic subsidence with high temporal resolution have yet to be accomplished, which constitute the primary objective of this study.…”