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= Tide-dominated Deltas = Tide-dominated deltas are deltas where the influence of tidal currents is greater than the influence of wave energy and river discharge[1]. The largest delta on earth currently is the Ganges-Brahmaputra Delta and is a tide-dominated delta.[1] Tide-dominated deltas often lack the traditional morphology a wave-dominated delta such as the Nile or a river-dominated  Mississippi river delta. It is important to note that although deltas can be classified as fluvial-, wave-, or tide-dominated,they typically show features of all three process regimes. Tide-dominated deltas are common around the world and make up some of the most important deltas to human civilization. There has been relatively little research into their evolution when compared to fluvial or wave dominated deltas[2].

Geomorphology
Tide-dominated deltas can be divided up into four geomorphic regions[2]; the tidal-fluvial channel, distributary channels and interdistributary islands, distributary-mouth bars and the delta front and prodelta[2]. The tidal-fluvial channel is a sinuous meandering channel with depths up to 15 meters on the outside of the meandering bends[2]. The channel experiences more tidal flux downstream toward the ocean, which increases the channel width and radius of curvature of the meander bends[2].

Distributary channels and the interdistributary islands are typically straight and sinuous and open seaward[2]. Depths of these channels reach about 20 meters in the Fly River Delta but can reach depths of up to 50 meters such as in the Han River delta[2][3]. These distributary channels can be sub-divided into ebb-dominated and flood-dominated channels. Ebb-dominated channels are continuous with the river channel, while flood channels terminate as flood barbs[2]. Tidal bars with relief on the scale of meters can be found within the distributary channels.Widths and lengths of tidal bars range from several hundred to thousands of kilometers[2][3]. Channel bars emerge at the surface and form islands as the bars propagate seaward[2].

Distributary-mouth bars are extensions of channel bar features[2]. The formation of these bars is controlled by tidal processes and these bars can extend for kilometers offshore (10-15 km in the Fly River Delta)[2]. Ancient tide-dominated delta mouth bar deposits exhibit a coarsening upward trend[3]. The relief of these bars can reach several meters in height, with relief decreasing in the offshore direction[2]. Much of the sand in the distal part of the system is deposited in these mouth bars before it can be transported to the shelf[2].

The delta front and prodelta arethe most distal areas of the delta. These areas are normally several kilometers offshore and deposits consist  mostly of extensive mud[2]. Coarser sediments may also be supplied to the prodelta during storm events[1]. Distinct tidal processes may not be prevalent in the prodelta region; instead, wave, current and storm processes may dominate this zone instead[1].

Formation
As with all deltas, tide-dominated systems require a river emptying into a body of water. Unlike other delta systems, the body of water into which the river empties is affected by the tidal currents. The tidal processes  dominante wave and fluvial processes, such that the sediment deposits are dominated by tidal structures[1].

Sedimentology
Most modern tide-dominated deltas are mud-dominated systems [1]. In the rock record, most tide-dominated deltas have been interpreted as sand-dominated. This discrepancy may be due to the overprinting of tidal processes over fluvial processes and due to the large scale of tide-dominated deltas that makes outcrop-scale observations difficult[1]. General grain-size in the system decreases seaward due to the current energy decreasing in the basinward direction, a decrease in transport capacity, and the tendency of coarser sediment to be deposited and resist erosion at a later point in time[4].

Delta Front/Plain Deposits
Crevasse splay, overbank, and delta plain lake deposits are common in this environment[5]. Crevasse splays form as breaches in the natural levee, resulting in the deposition of sand over the floodplain adjacent to the distributary channel[5]. These deposits can be on the meter scale, usually consisting of sandstones interbedded with delta plain mudstones. Crevasse splay deposits tend to be lobe shaped[5]. Interdistributary lakes produce thick mudstones[5]. Fossils of organisms that can survive in brackish water environments are common in these mudstones. Root traces are common, as well as mudcrack structures[5].

Channel Deposits
Most sediment of a tide-dominated delta is represented by channel deposits[4]. The size and shape of these channels changes systematically as the environment changes from an fluvial to marine [4]. Tidal flux is the main control of this change; as the delta moves into the marine environment, the amount of tidal flux increases[4]. Consequently, the channels widen exponentially seaward, resulting in the characteristic funnel-shaped geometry of tide-dominated delta distributary channels[4]. Channel bars migrate laterally and are analogous to point bar deposits. The bars move laterally due to their formation on the inside of a channel bend and their oblique angle to prevailing currents creates a side of weak current and a side of strong current[4]. Sediment is eroded from the strong current side "stoss side" and deposited in the weak current side "lee side"[4]. The bar deposits typically have an erosive base due to the location of the thalweg at the base of the migrating bar[4]. The bars typically have a fining upward trend on the lee side due to the decreasing energy from the bottom of the bar to the top[4]. Abandoned channels accumulate deposition of mud falling out of suspension[5]. Preserved mud deposits can show root traces and mudcrack structures[5].

In addition to bar deposits, ripple and dune bedforms can form on the channel floor[4]. These begin as river flow-dominated structures, then as the delta moves seaward they become more influenced by the tides[4]. In more seaward settings mud drapes will appear, indicating a slack water deposit between ebb and flood currents[4]. Herringbone cross-bedding is common where bi-directional currents cause migration of beforms in both the seaward and landward directions[4].

Prodelta
Prodelta deposits make up the most distal portions of the delta. These deposits are mostly mud that has fallen out of suspension in a low energy environment[5]. These sediments show parallel laminations when preserved(unless bioturbated...). Sand and silt can also be deposited in the prodelta environment via traction currents, mainly during storms.[5]. Sandstones and siltstones preserved in this environment can show ripple-lamination[5].

Economic Importance
Ancient tide-dominated deltas have been drilled for hydrocarbon reserves and modern tide-dominated deltas support millions of people due to the fertile land around them.

Examples of Tide-dominated Deltas
=== Modern Examples ===


 * Ganges-Brahmaputra Delta
 * Colorado Delta
 * Indus Delta
 * Changjiang (Yangtze) Delta
 * Mekong Delta
 * Fly Delta
 * Amazon Delta
 * Copper River Delta
 * Shatt-al-Arab (Tigris-Euphrates) Delta
 * Ayeyarwady Delta
 * Mahakam Delta

=== Preserved Examples ===


 * Jurassic Curtis, Summerville, and Stump Formations
 * Dir Abu Lifa member delta