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1984
- handle: 10670/1.lj7n3j
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Eric Davaud et al., « Cimentation et structures sédimentaires des beach-rocks : genèse et critères d'identification », MOM Éditions, ID : 10670/1.lj7n3j
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Two examples of carbonate-beach rock formation have been studied in Tunisia and on the Bahamas. It appears evident that cementation takes place under a cover of sediment where the carbonate grains are immobilized and where primary cements are precipitated in a marine or fresh-water, phreatic or vadose environment close to the water table. Oblique beach stratification and keystone vugs (typical for the swash zone) are thus preserved. Coastal erosion exposes this preferentially cemented layer, and marine cementation in the intertidal zone further indurates the rock. Wave action often washes away the underlying non-consolidated sediment. This causes the beach rock to break into blokes which (by gravity) may glide into the subtidal zone. Except for secondary marine vadose cements, all cements types found in beach rocks also occur in other environments. The identification of ancient beach rocks should therefore not be based on cementation criteria only, but also on sedimentary structures and on stratigraphic context.