A Flexural Model for the Paradox Basin: Implications for the Tectonics of the Ancestral Rocky Mountains

Persistent Link:
A Flexural Model for the Paradox Basin: Implications for the Tectonics of the Ancestral Rocky Mountains
Barbeau, David Longfellow Jr.
Issue Date:
The University of Arizona.
Copyright © is held by the author. Digital access to this material is made possible by the Antevs Library, Department of Geosciences, and the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author or the department.
Collection Information:
This item is part of the Geosciences Theses collection. It was digitized from a physical copy provided by the Antevs Library, Department of Geosciences, University of Arizona. For more information about items in this collection, please email the Antevs Library, antevs@geo.arizona.edu.
The Paradox Basin is a large (200 km x 265 km) asymmetric basin that developed along the southwestern flank of the basement-involved Uncompahgre uplift during the Pennsylvanian-Permian (Desmoinesian-Wolfcampian) Ancestral Rocky Mountain (ARM) orogenic event. Traditionally interpreted as a pull-apart basin, the Paradox Basin more closely resembles intraforeland flexural basins such as those that developed between the basement-cored uplifts of the Late Cretaceous-Eocene Laramide orogeny. The width, shape, subsidence history, facies architecture, and structural relationships of the Uncompahgre-Paradox system are exemplary of typical 'immobile' foreland basin systems. Along the southwest-vergent Uncompahgre thrust, ~5 km of coarse-grained syntectonic Desmoinesian-Wolfcampian sediments were shed from the Uncompahgre uplift by alluvial fans and were reworked by fluvial megafan deposystems in the proximal Paradox Basin. The coeval rise of an uplift-parallel barrier ~250 km southwest of the Uncompahgre front restricted reflux from the open ocean south and west of the basin, and promoted deposition of thick evaporite-shale and biohermal carbonate facies in the medial and distal, submarine parts of the basin, respectively. Nearshore carbonate shoal and terrestrial siliciclastic deposystems overtopped the basin during the late stages of subsidence during the Missourian through Wolfcampian. Reconstruction of an end-Permian two-dimensional uplift-basin profile from seismic, borehole, and outcrop data depicts the relationship of these deposystems to the differential accommodation space (i.e., foreland basin depozones) generated by Pennsylvanian-Permian subsidence. Flexural modeling of the restored basin profile indicates that the Paradox Basin can be described by flexural loading of a fully broken continental crust (Te = 25 km; D = 10²³ N m) by a model Uncompahgre uplift (A(c-s) = 214 km², ρ = 2670 kg /m³) and accompanying synorogenic sediments (ρ = 2325 kg /m³). The Paradox Basin's lack of flexural interference by competing loads, its location on the relatively undeformed Colorado Plateau, and its well-exposed and well-studied basin-fill provide a rare glimpse into a Paleozoic intraforeland flexural basin. Other thrust-bounded basins of the Ancestral Rocky Mountains are not so optimal for study. However, similarities in basin profiles, structural relationships and facies architectures suggest that many ARM basins share a geodynamic and tectonic history similar to the Paradox Basin's. Therefore, plate tectonic models that attempt to explain the development of ARM uplifts need to also consider the province's intraforeland flexural basins.
text; Thesis-Reproduction (electronic)
basement tectonics; basin analysis; basins; biogenic structures; bioherms; biostratigraphy; Carboniferous; Cenozoic; chemically precipitated rocks; Colorado; correlation; cycles; data; deformation; depositional environment; Desmoinesian; evaporites; faults; flexure; foreland basins; fossils; Four Corners; geophysical methods; ichnofossils; Invertebrata; Laramide Orogeny; lithofacies; lithostratigraphy; Mesozoic; Middle Pennsylvanian; models; North America; oil wells; paleoenvironment; paleogeography; Paleozoic; Paradox Basin; Paradox Member; Pennsylvanian; Permian; petroleum; petroleum exploration; reconstruction; reservoir rocks; Rocky Mountains; sedimentary rocks; sedimentary structures; sedimentation; seismic methods; stratigraphic units; stratigraphic wedges; subsidence; tectonics; Tertiary; thickness; thrust faults; Uncompahgre Uplift; United States; uplifts; Utah; well logs
Degree Name:
Degree Level:
Degree Program:
Graduate College; Geosciences
Degree Grantor:
University of Arizona

Full metadata record

DC FieldValue Language
All Items in UA Campus Repository are protected by copyright, with all rights reserved, unless otherwise indicated.