Preliminary data on the coral distribution in the Upper Visean (Mississippian) succession from Adarouch area (NE Central Morocco)

摘要

The Early Carboniferous (Mississippian) sequences of the Adarouch area (NE Central Morocco) are subdivided into four lithostratigraphic units: the Oued Amhares Formation, the Tizra Formation, the Mouarhaz Formation and the Akerchi Formation (BERKHLI, 1999). Rugose corals are present throughout most of the succession but they are abundant only in the Tizra and Akerchi formations. Only the second and third members (TZ2, TZ3) of the Tizra Formation, that were sedimented on a ramp, yielded abundant corals. TZ2 yielded Lithostrotion, Siphononodendron and Palaeosmilia. TZ3 yielded Siphononodendron, Lithostrotion, Diphyphyllum, Lublinophyllum?, Clisiophyllum, Palaeosmilia, Palastraea, Dibunophyllum, Arachnolasma, Koninckophyllum, Siphonophyllia, Haplolasma, Pseudozaphrentoides, Corwenia, Aulokoninckophyllum, Axophyllum and tabulates micheliniids and syringoporoids. TZ2 is Asbian in age and TZ3 is Brigantian in age. The assemblage from Akerchi Formation, that was sedimented in a shallow platform, is composed of Siphonodendron, Diphyphyllum, Lithostrotion, Palastraea, Paleosmilia, Clisiophyllum, Dibunophyllum, Axophyllum, Arachnolasma and Koninckophyllum. This assemblage is Brigantian in age. An isolated outcrop located east of Akerchi, at Idmarrach, provided a rich coral assemblage composed of Lithostrotion, Siphonodendron, Diphyphyllum, Palastraea, Palaeosmilia, Dibunophyllum, Arachnolasma, Clisiophyllum, Koninckophyllum, Aulophyllum, Siphonophyllia, Axophyllum and common syringoporoids. The presence of Palastraea regia establishes the age of the Idmarrach section as Brigantian or younger.