Tidal straits: Basic criteria for recognizing ancient systems from the rock record

Tidal straits are characteristic narrow marine passageways constricted between emerged or shallowly submerged landmasses, where tidal flows undergo phenomena of hydraulic amplification if repeatedly and cyclically moving through the narrowest strait centre. Modern systems share general hydrodynamic and sedimentological aspects if governed by tidal forces. Tidal currents reproduce characteristic bottom features and sediment accumulations that generate predictable facies tracts and stratigraphies that can be used as proxy to decipher ancient strait deposits preserved in outcrop or subsurface. Straits are here regarded as individual depositional systems, including definite environments or sedimentary zones. We describe the stratigraphic and sedimentological features here suggested to be diagnostic for identifying the strait centre, the dune-bedded zones, the strait-end zones, as well as the strait margins, based on the observation of some tide-influenced or tide-dominated reference ancient system.