THE BRACHIOPODS OF THE WESTERN-ALGERIAN F ORELAND DURING THE MAXIMUM TRANSGRESSIVE INTERVAL OF UPPER BERRIASIAN AGE (BOISSIERI ZONE) - SYSTEMATICS, ENVIRONMENT AND PALEOGEOGRAPHY

The rich brachiopod fauna of Upper Berriasian age (Boissieri zone) in the Oranian Tellian foreland, is studied for the first time from the t axonomic point of view. The description of species takes account of bo th external and internal morphological characters. The microstructural details revealed by the scanning electron microscope show growth rhyt hms and the diagenetic evolution of the shells. Comparison of the Nort h Africa Berriasian-Valanginian fauna with that of Europe indicates th at the palaeogeographic distribution of certain brachiopod species was controlled by latitude and by climate. Finally, the assemblage of pal aeoenvironmental and palaeoecological faunal associations is emphasize d with brachiopod biocoenoses closely related to the transgressive pha se represented by the Boissieri zone. The transgressive phase is part of a 3rd-order depositional sequence (in Vail's sense) dating from the Middle Berriasian to the Late Berriasian on the south-west margin of Tethys.