scholarly journals Supplemental Material: Constraining the effects of dynamic topography on the development of Late Cretaceous Cordilleran foreland basin, western United States

2021 ◽  
Author(s):  
Zhiyang Li ◽  
Jennifer Aschoff
Keyword(s):  
United States ◽  
Late Cretaceous ◽  
Foreland Basin ◽  
Well Logs ◽  
Western United States ◽  
Dynamic Topography ◽  
Cordilleran Foreland

Table S1 includes sources for the chronostratigraphic framework in Figure 3 and Table S2 includes information of well logs shown in Figure 4.

scholarly journals Supplemental Material: Constraining the effects of dynamic topography on the development of Late Cretaceous Cordilleran foreland basin, western United States

2021 ◽  
Author(s):  
Zhiyang Li ◽  
Jennifer Aschoff
Keyword(s):  
United States ◽  
Late Cretaceous ◽  
Foreland Basin ◽  
Well Logs ◽  
Western United States ◽  
Dynamic Topography ◽  
Cordilleran Foreland

Table S1 includes sources for the chronostratigraphic framework in Figure 3 and Table S2 includes information of well logs shown in Figure 4.

Constraining the effects of dynamic topography on the development of Late Cretaceous Cordilleran foreland basin, western United States

2021 ◽  
Author(s):  
Zhiyang Li ◽  
Jennifer Aschoff
Keyword(s):  
High Resolution ◽  
Late Cretaceous ◽  
Large Scale ◽  
Upper Cretaceous ◽  
Foreland Basin ◽  
Dynamic Topography ◽  
Data Set ◽  
Cordilleran Foreland ◽  
And Migration ◽  
Dynamic Subsidence

Dynamic topography refers to the vertical deflection (i.e., uplift and subsidence) of the Earth’s surface generated in response to mantle flow. Although dynamic subsidence has been increasingly invoked to explain the subsidence and migration of depocenters in the Late Cretaceous North American Cordilleran foreland basin (CFB), it remains a challenging task to discriminate the effects of dynamic mantle processes from other subsidence mechanisms, and the spatial and temporal scales of dynamic topography is not well known. To unravel the relationship between sedimentary systems, accommodation, and subsidence mechanisms of the CFB through time and space, a high-resolution chronostratigraphic framework was developed for the Upper Cretaceous strata based on a dense data set integrating >600 well logs from multiple basins/regions in Wyoming, Utah, Colorado, and New Mexico, USA. The newly developed stratigraphic framework divides the Upper Cretaceous strata into four chronostratigraphic packages separated by chronostratigraphic surfaces that can be correlated regionally and constrained by ammonite biozones. Regional isopach patterns and shoreline trends constructed for successive time intervals suggest that dynamic subsidence influenced accommodation creation in the CFB starting from ca. 85 Ma, and this wave of subsidence increasingly affected the CFB by ca. 80 Ma as subsidence migrated from the southwest to northeast. During 100−75 Ma, the depocenter migrated from central Utah (dominantly flexural subsidence) to north-central Colorado (dominantly dynamic subsidence). Subsidence within the CFB during 75−66 Ma was controlled by the combined effects of flexural subsidence induced by local Laramide uplifts and dynamic subsidence. Results from this study provide new constraints on the spatio-temporal footprint and migration of large-scale (>400 km × 400 km) dynamic topography at an average rate ranging from ∼120 to 60 km/m.y. in the CFB through the Late Cretaceous. The wavelength and location of dynamic topography (subsidence and uplift) generated in response to the subduction of the conjugate Shatsky Rise highly varied through both space and time, probably depending on the evolution of the oceanic plateau (e.g., changes in its location, subduction angle and depth, and buoyancy). Careful, high-resolution reconstruction of regional stratigraphic frameworks using three-dimensional data sets is critical to constrain the influence of dynamic topography. The highly transitory effects of dynamic topography need to be incorporated into future foreland basin models to better reconstruct and predict the formation of foreland basins that may have formed under the combined influence of upper crustal flexural loading and dynamic subcrustal loading associated with large-scale mantle flows.

scholarly journals A magnetostratigraphic age constraint for the proximal synorogenic conglomerates of the Late Cretaceous Cordilleran foreland basin, northeast Utah, USA

2020 ◽  
Author(s):  
Ziaul Haque ◽  
John W. Geissman ◽  
Peter G. DeCelles ◽  
Barbara Carrapa
Keyword(s):  
Late Cretaceous ◽  
Foreland Basin ◽  
Magnetic Polarity ◽  
Coarse Grained ◽  
Sediment Provenance ◽  
Fine Grained ◽  
Magnetic Carriers ◽  
Normal Polarity ◽  
Cordilleran Foreland ◽  
Geomagnetic Polarity

Reliable ages of proximal conglomerates in the Cordilleran foreland basin that are associated with emplacement and erosion of major thrust sheets are essential for reconstructing the kinematic history of the Sevier fold-thrust belt. Although these conglomerates have been dated by palynology, their absolute ages have been difficult to determine because of their coarse-grained texture and a lack of marine interbeds and tuffaceous deposits. We collected sets of oriented samples from outcrops in northeastern Utah, USA, to construct an overall magnetic polarity stratigraphy that can be correlated to the geomagnetic polarity time scale (GPTS). We sampled fine-grained, hematitic interbeds in the Upper Cretaceous Echo Canyon Conglomerate and Weber Canyon Conglomerate. Common paleomagnetic and rock magnetic analyses were conducted, and several rock magnetic results indicated that the dominant magnetic carriers in these weakly magnetized rocks are hematite and very subordinate magnetite/titanomagnetite/maghemite and goethite. Demagnetization results show that hematitic, fine-grained sandstone to siltstone intervals carry a geologically stable magnetization with directions and polarity consistent with the Late Cretaceous geomagnetic field. A small percentage of samples carry a low laboratory unblocking temperature secondary overprint residing primarily in goethite. Magnetic polarity results indicate that the Echo Canyon Conglomerate is exclusively of normal polarity and that the younger Weber Canyon Conglomerate is of normal polarity in its lowermost part, reverse polarity in the middle, and normal polarity in the upper part of the sequence. The new data indicate that these coarse-grained strata were most likely deposited over the time span of the magnetic polarity Chron (C) 34n to C33r interval and the younger C33r to C33n interval; the former interval includes the Santonian-Campanian stage boundary (ca. 83.4 Ma/83.1 Ma). Palynological data suggest that these rocks span Coniacian-Santonian time (ca. 89−84 Ma); thus, the most parsimonious correlation of the normal polarity magnetozone of the Echo Canyon Conglomerate is with the youngest part of C34n Superchron, which is of ca. 30 Ma duration (ca. 115 Ma to 83.4 Ma/83.1 Ma). The normal polarity magnetozone of the lower part of the younger Weber Canyon Conglomerate likely correlates to the youngest part of C34n, whereas the reverse and normal magnetozone from the middle and upper parts of the Weber Canyon Conglomerate likely correlate to C33r and C33n, respectively. We infer that the Santonian-Campanian boundary resides in the lower Weber Canyon Conglomerate, which implies that deposition of the unit started prior to the C34n/C33r boundary age (ca. 83.4 Ma/83.1 Ma) and continued through the C33r and C33n chrons. Sediment provenance data and growth structures tie the Echo Canyon and Weber Canyon Conglomerates to emplacement of the Crawford thrust sheet. Based on the magnetic polarity data, as constrained by the biostratigraphic age estimates from these synorogenic deposits, we hypothesize that the principal displacement along the Crawford thrust started during the Coniacian (>C34n/C33r boundary age) and continued into the middle Campanian (<C33r/C33n boundary age), from ca. 90−75 Ma, which is nearly 10 Ma longer than previously thought. The new age constraints demonstrate complete temporal overlap between proximal and distal coarse-grained deposits in this part of the Cordilleran foreland basin, coeval with active thrust displacement and rapid hinterland exhumation.

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