Tidal dynamics in palaeo‐seas in response to changes in physiography, tidal forcing and bed shear stress

Abstract

Simulating hydrodynamic conditions in palaeo-ocean basins is needed to better understand the effects of tidal forcing on the sedimentary record. When combined with sedimentary analyses, hydrodynamic modelling can help inform complex temporal and spatial variability in the sediment distribution of tide-dominated palaeo-ocean basins. Herein, palaeotidal modelling of the epicontinental Upper Jurassic (160 Ma, lower Oxfordian) Sundance and Curtis seas of North America reveals possible regional-scale variations in tidal dynamics in response to changes in ocean tidal forcing, physiographic configuration and bottom drag coefficient. A numerical model forced with an M2 tidal constituent at the open boundary shows that the magnitude and location of tidal amplification, and the variability in current velocity and bed shear stress in the basin, were controlled by palaeophysiography. Numerical results obtained using a depth of 600 m at the ocean boundary of the system enable the prediction of major facies trends observed in the lower Curtis Formation. The simulation results also highlight that certain palaeophysiographic configurations can either permit or prevent tidal resonance, leading to an overall amplification or dampening of tides across the basin. Furthermore, some palaeophysiographic configurations generated additional tidal harmonics in specific parts of the basins. Consequently, similar sedimentary successions can emerge from a variety of relative sea-level scenarios, and a variety of sedimentary successions may be deposited in different parts of the basin in any given relative sea-level scenario. These results suggest that the interpretation of sedimentary successions deposited in strongly tide-influenced basins should consider changes in tidal dynamics in response to changing sea level and basin physiography.

The sedimentological expression of transgression–regression cycles upon aeolian–marine margins

“…It is possible that perennial fluvial system discharge variability in fully fluvial or estuarine settings could produce cyclical bedforms and sedimentary structures, not unlike the ones observed in this facies belt (Martinius & Gowland, 2011; Reesink & Bridge, 2011). However, the lack of such perennial fluvial systems preserved in the rock record, coupled with the abundance of tidal indicators such as bidirectional current ripples, double and single mud drapes and tidal bundles (Kreisa & Moila, 1986), along with a physiography that can generate very amplified tidal currents (Zuchuat et al, 2022), indicates that tidal processes played an important role in the deposition of this facies belt.…”

“…The Persian Gulf is a microtidal seaway with a tidal range of ca 1–2 m (Lokier et al, 2015) and does not completely deflate the dune field prior to the interaction of the marine system to the subtidal zone. The Sundance Sea that deposited the Curtis Formation is a mesotidal environment with a tidal range of ca 2.6 m (see Zuchuat et al, 2022 and references therein), in addition to being in a state of tidal resonance, which could further enhance the efficiency of tidal current to rework aeolian sand. Further, this high aeolian sand‐supply associated with a lack of consolidated mud tends to dissipate the tidal energy less than if consolidated mud occurs in the system, leading to overall stronger tidal currents (Gabioux et al, 2005).…”

“…The Moab Member of the Curtis Formation comprises deposits of a coastal erg which developed at the south‐eastern edge of a NNE–SSW‐oriented retro‐arc foreland basin, known as the Utah–Idaho Trough (Bjerrum & Dorsey, 1995). During the Late Jurassic, the foreland basin was periodically flooded during the south‐easterly expansion of the Sundance Sea (Anderson & Lucas, 1994; Brenner & Peterson, 1994; Caputo & Pryor, 1991; Danise et al, 2020; Danise & Holland, 2017, 2018; Imlay, 1952, 1980; Kreisa & Moila, 1986; Pipiringos & O'Sullivan, 1978; Thorman, 2011; Wilcox & Currie, 2008; Zuchuat et al, 2018, 2019a, 2019b, 2022).…”

“…The Entrada–Curtis–Summerville succession exposed in south‐eastern Utah documents the evolution of an arid coastal erg system that interacts with a neighbouring shallow sea. The Curtis and Summerville formations were, respectively, deposited within, and next to, a narrow seaway that extended from the Sundance Sea during the Oxfordian Age (Caputo & Pryor, 1991; Kreisa & Moila, 1986; Wilcox & Currie, 2008; Zuchuat et al, 2018 and references therein), in which tidal resonance (Collins et al, 2018) temporarily developed during periods of optimal physiographical conditions (Zuchuat et al, 2022). During phases of amplified tidal forces, autogenic processes have the potential to overprint the stratigraphical signature of autocyclic processes (Zuchuat et al, 2019b).…”

Unconformity generation and the shift from storm‐dominated to tide‐dominated processes in a Jurassic retroarc foreland basin: Insights from ichnology

“…This contrasts with the prograding of intertidal flats, tidal inlets and tidal dunes directly over lower shoreface to offshore deposits that is observed in the Windy Hill and Upper Sundance/Redwater Shale contact across Wyoming (Danise & Holland, 2017, 2018; Holland & Wright, 2020). There is no evidence for fluvial incision at the contact either (Holland & Wright, 2020), although the Sheridan Arch, ancestral Front Range and Uncompahgre Uplift, helped drive the regional drop in relative sea level and created palaeobathymetric high spots that may have amplified tidal currents (Dean et al, 2019; Zuchuat et al, 2022). Of all the candidate mechanisms for generating a regionally widespread, basinward‐step in facies, the only one that accounts for all the sedimentological, ichnological and stratigraphic characteristics of the J‐5 unconformity in southern Wyoming is a forced regression caused by tectonic uplift of the ancestral Front Range and other pre‐Laramide structures, which progressively migrated from southern Wyoming to northern Wyoming.…”