Regional-scale paleobathymetry controlled location, but not magnitude, of tidal dynamics in the Late Cretaceous Western Interior Seaway, USA

Abstract

Despite extensive outcrop and previous sedimentologic study, the role of tidal processes along sandy, wave- and river-dominated shorelines of the North American Cretaceous Western Interior Seaway remains uncertain, particularly for the extensive mid-Campanian (ca. 75–77.5 Ma) tidal deposits of Utah and Colorado, USA. Herein, paleotidal modeling, paleogeographic reconstructions, and interpretations of depositional process regimes are combined to evaluate the regional-scale (hundreds to thousands of kilometers) basin physiographic controls on tidal range and currents along these regressive shorelines in the “Utah Bight”, southwestern Western Interior Seaway. Paleotidal modeling using a global and astronomically forced tidal model, combined with paleobathymetric sensitivity tests, indicates the location of stratigraphic units preserving pronounced tidal influence only when the seaway had a deep center (∼400 m) and southern entrance (>100 m). Maximum tidal velocity vectors under these conditions suggest a dominant southeasterly ebb tide within the Utah Bight, consistent with the location and orientation of paleocurrent measurements in regressive, tide-influenced deltaic units. The modeled deep paleobathymetry increased tidal inflow into the basin and enhanced local-scale (tens to hundreds of kilometers) resonance effects in the Utah Bight, where an amphidromic cell was located. However, the preservation of bidirectional, mudstone-draped cross-stratification in fine- to medium-grained sandstones requires tides in combination with fluvial currents and/or local tidal amplification below the maximum resolution of model meshes (∼10 km). These findings suggest that while regional-scale controls govern tidal potential within basins, localized physiography exerts an important control on the preservation of tidal signatures in the geologic record.

Cretaceous to Recent net continental uplift from paleobiological data: Insights into sub-plate support

“…Paleobathymetric estimates from the PBDB broadly agree with independent values. For example, they are consistent with local water-depth maxima estimated using the height of clinoforms (40 m, Plint et al, 2009), planktonic to benthic foraminifera ratios (500 m, Eicher , 1969) and numerical simulation of oceanic circulation (100-400 m, Ericksen and Slingerland , 1990;Dean et al, 2019). Arthur and Sageman (2004) correlated depositional environments, lithofacies and water depths in modern marine settings to infer maximum water depths of 200-300 m across most of the Cretaceous seaway, with local maxima of 1000 m. These values and smoothly varying paleowater-depth estimates indicate that a modern analogue is the Hudson Bay, a large, ∼ 1000 km-wide seaway that has an undulated bottom in most parts and a mean water depth of ∼ 150 m (GEBCO; Stewart and Lockhart, 2006).…”

Fernandes and Roberts (2020) - preprint

“…Paleobathymetric estimates from the PBDB broadly agree with independent values. For example, they are consistent with local water-depth maxima estimated using the height of clinoforms (40 m, Plint et al, 2009), planktonic to benthic foraminifera ratios (500 m, Eicher , 1969) and numerical simulation of oceanic circulation (100-400 m, Ericksen and Slingerland , 1990;Dean et al, 2019). Arthur and Sageman (2004) correlated depositional environments, lithofacies and water depths in modern marine settings to infer maximum water depths of 200-300 m across most of the Cretaceous seaway, with local maxima of 1000 m. These values and smoothly varying paleowater-depth estimates indicate that a modern analogue is the Hudson Bay, a large, ∼ 1000 km-wide seaway that has an undulated bottom in most parts and a mean water depth of ∼ 150 m (GEBCO; Stewart and Lockhart, 2006).…”

Climatic and tectonic drivers shaped the tropical distribution of coral reefs

“…refs. 73 , 100 , 101 ), and are utilised as the boundary conditions for climate simulations, providing spatially explicit data for when continent configuration, topography, and bathymetry were different from today 102 . To correspond with climate layers, all DEMs were aggregated to a horizontal resolution of 1° × 1°, while preserving the minimum depth within the cell.…”