Page 256 - Sedimentology and Stratigraphy

Marine Evaporites 243

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Fig. 15.19 Settings where barred
basins can result in thick successions
of evaporites.

3 A deep-water to deep-basin setting is a basin filled Deep-basin succession can show two different pat-
with hypersaline water in which evaporite sediments terns of deposition (Einsele 2000). If the barred basin is
are formed at the shallow margins and are redeposited completely enclosed the water body will gradually
by gravity flows into deeper parts of the basin. Nor- shrink in volume and area and the deposits that result
mally graded beds generated by turbidites and poorly will show a bulls-eye pattern with the most soluble
sorted deposits resulting from debris flows are evidence salts in the basin centre (Fig. 15.20). In circum-
of redeposition. Other deep-water facies are laminated stances where there is a more permanent connection
deposits produced by settling of crystals of evaporite a gradient of increasing salinity from the connection
minerals out of the water body. As a basin fills up, the with the ocean to the furthest point into the basin will
lower part of the succession will be deeper water facies exist. The minerals precipitated at any point across
and the overlying succession will show characteristics the basin will depend on the salinity at the point and
of shallow-water deposition. may range from highly soluble sylvite (potassium