Lithostratigraphy of the littoral deposits of the last one million years in the Casablanca region (Morocco) / Lithostratigraphie des dépôts littoraux contemporains du dernier million d'années dam la région de Casablanca (Maroc),

摘要

Littoral deposits of the Casablanca region have provided most of the stratotypes for the Quaternary manne «stages» of the Maghreb. A part of these deposits is the subject here of a new hthostratigraphic approach mainly based on the study of faciès association, as well as diagenetic processes. This has permitted the identification of ten (possibly twelve) high-resolution sequences. These units all probably accumulated over the last million years. The sequences are progradational and, most of the time, record a relatively straightforward history. They result from an abrupt rising followed by a gradual falling of the sea level. Sedimentary structures indicate upper shoreface (sometimes), foreshore, backshore and aeolian dune depositional environments Runoff and mud or debris-flow are probably the main processes involved in the deposition of the slope deposits intercalated in this stratigraphie series. Moreover, the results show that the classic chronostratigraphic framework so far used in the Maghreb is inadequate because of incorrect correlations and chronological attnbutions, previously unidentified formations and the definition of distinct «stages» from the same stratigraphie unit. In view of these problems, this classic framework must be abandoned.