Deciphering the relative importance of fluvial and tidal processes in the fluvial–marine transition

Depositional evolution of a progradational to aggradational, mixed-influenced deltaic succession: Jurassic Tofte and Ile formations, southern Halten Terrace, offshore Norway

“…The poor sorting and coarse grain size of sandstones in the lower part of the succession indicates that texturally immature sediment was transported and deposited by strong unidirectional currents during times of high fluvial discharge (Dalrymple et al, 2015;Gugliotta et al, 2015;Gugliotta et al, 2016;Jablonski and Dalrymple, 2016). The presence of mud drapes and the heterolithic toesets of cross-beds is indicative of bedforms formed by tidal currents (Boersma, 1969;Terwindt, 1971;Van den Berg et al, 2007).…”

“…The presence of mud drapes and the heterolithic toesets of cross-beds is indicative of bedforms formed by tidal currents (Boersma, 1969;Terwindt, 1971;Van den Berg et al, 2007). The heterolithic mudstones and sandstones (facies F4c,e), which are interbedded with coarser grained sandstones, reflect tidal current deposition during periods of low fluvial discharge (Dalrymple et al, 2015;Gugliotta et al, 2016;Jablonski and Dalrymple, 2016). The homogenous mudstones (facies F4b and F4d) resemble fluid mudstones, indicating that wave action or tidal currents kept mud formed by salinity-induced mud flocculation in suspension (Ichaso and Dalrymple, 2009).…”

Recognition criteria, characteristics and implications of the fluvial to marine transition zone in ancient deltaic deposits (Lajas Formation, Argentina)

“…Important controls on the extent and character of the FMTZ are the coastal‐plain gradient, the tidal range at the coast and the fluvial discharge (Dalrymple et al ., ). Over short‐time periods, the position and length of the subzones of the FMTZ will change due to fluvial discharge variations (for example, seasonal discharge; Sisulak & Dashtgard, ; Dalrymple et al ., ; Gugliotta et al ., ; Jablonski & Dalrymple, ) or cyclic fluctuations in tidal current strength (for example, neap–spring cycles), producing landward and seaward shifts of the subzone along the river profile (Allen et al ., ; van den Berg et al ., ; Dalrymple & Choi, ; Kravtsova et al ., ). Over longer periods, the FMTZ may vary due to physiographic changes and/or relative sea‐level fluctuations.…”

“…In the study of ancient deposits, the fluvial to marine transition zone or similar terms have been used to describe stratigraphic changes from interpreted marine or tidal to fluvial deposits (Simpson et al ., ; Makhlouf, ; Eriksson et al ., ; Abouessa et al ., ). The term has rarely been applied to interpret down dip changes in time‐equivalent deposits that formed within a well‐defined zone with mixed fluvial and marine energy (van den Berg et al ., ; Martinius & Gowland, ; Martinius & Van den Berg, ; Martinius et al ., ) or to describe the interaction of fluvial and marine processes during deposition (Ghosh et al ., ; Dalrymple et al ., ; Gugliotta et al ., ; Jablonski & Dalrymple, ). Therefore, the understanding of interactions between several processes in the fluvial to marine transition zone and how these are preserved into the rock record is still poorly constrained.…”

Fluvial to tidal transition zone facies in the McMurray Formation (Christina River, Alberta, Canada), with emphasis on the reflection of flow intensity in bottomset architecture

“…In the FTT unidirectional, freshwater (fluvial) flow interacts with the tides and the intruding salty and denser seawater. This interaction can be relatively simple but may also lead to a multifaceted hydrodynamic regime, involving salinity changes as well, resulting in a signal in the rock record that is not straightforward to interpret (Dalrymple et al, 2015;Dalrymple and Choi, 2007;Jablonski, 2012). 12.1) in an estuary or a (tide-dominated) delta distributary.…”