at a given site. In this context, for instance, using the
Gironde Estuary from France as a model, Allen and
Posamentier (1993) highlighted the facies types in
terms of lithology and sedimentary structures along
tide-dominated estuaries and the small-scale stratigraphy
diagnostic of each sub-environment within such estuaries
(Figure 6).
The main sedimentary environments, or facies, that
occur within an estuary from landward to seaward are as
follows (Figure 7):
1. The major estuarine-head delta(s)
2. Subsidiary deltas
3. Marginal estuary alluvial fans
4. Spits and their lagoons
5. Marginal estuary environments, comprising platforms, tidal flats, mangrove- and/or salt marshvegetated tidal flats, and biostromes
6. Central estuary basin, comprising deepwater
environments
7. Central estuary channels
Stratigraphy of Estuaries, Figure 9 The idealized diagnostic small-scale sedimentary features and their bioturbated equivalents of
the different sub-environments/facies of a tide-dominated estuary (Diagram based on estuarine model of Dalrymple et al. (1992),
with approach of Allen and Posamentier (1993), for illustrating the character of the small-scale facies).
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STRATIGRAPHY OF ESTUARIES