| Popis: |
The transgressions and regressions in the Atlas Gulf control the facies of the clastic deposits during the Early Cretaceous. As the coastline oscillates, the succession of varied environments migrates systematically landward and seaward. Large terrigenous supply is characteristic of regressive periods (Upper Hauterivian, Lower Aptian) and small supply of transgressive periods (Valanginian, Barremian, Upper Aptian). The distributive province of the terrigenous detritus in the eastern hinterland of the gulf (e.g., the Precambrian crystalline massifs of the Central High Atlas) remains constant. The clastics, transported westward through the Atlas Basin and decreasing in grain size, reach the continental slope and are deposited as turbidites in the contemporaneous offshore sediments in DSDP Site 370/416. The following sedimentological and petrographical parameters were used for the analysis of the paleogeographical and paleoenvironmental development: The directional distribution of cross bedding and sole marks, the feldspar content, the regional distribution of the main constituents (insoluble residue, calcite, and dolomite), the calcium content of the dolomites, the change of the sediment thickness, and the occurrence of corals and redbeds. |
