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 tomore »
Tectonic Forcing, Subsidence, and Sedimentary Cyclicity in the Upper Cretaceous, Western Interior U.S.A.
Sequence stratigraphy is an observationally-based method for interpreting sedimentary cyclicity. Stacking patterns of progradation, retrogradation and degradation are related to the balance of sedimentary accommodation versus sediment supply. While often related to eustasy, accommodation is also controlled by tectono-subsidence. Based on over 50 global examples, regional subsidence and uplift rates are usually greater than rates of sea level rise/fall for durations greater than about one million years. Thus, in many basins, the larger scale patterns of sedimentary cyclicity are driven by tectonics.
The Upper Cretaceous of the Western Interior is an ideal laboratory to evaluate stratigraphic response to tectono-subsidence. Based on the stratigraphic framework, geohistory analyses, mapped shorelines and interpreted 2nd order system tracts, there is a strong correlation between subsidence rates and shoreline trajectories/stacking patterns. Large scale transgressions correlate with marked increases in subsidence, while strongly regressive intervals correspond to periods of low subsidence (or uplift). For example, the widespread transgression that occurs above the Turonian (e.g., Niobrara-Baxter-Cody) is associated with a large increase in regional subsidence. And the strongly progradational interval in the Upper Campanian that occurs throughout Wyoming (e.g., Ericson-Pine Ridge-Teapot) corresponds with uplift in proximal areas and reduced subsidence rate in more distal areas.
Moreover, the patterns of more »
- Award ID(s):
- 1824538
- Publication Date:
- NSF-PAR ID:
- 10109586
- Journal Name:
- AAPG Annual Convention and Exhibition
- Sponsoring Org:
- National Science Foundation
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