Geology, facies model and coral associations of the Late Jurassic reef complex at Cape Ghir (Atlantic High Atlas, Morocco)

A quantitative study of the Upper Jurassic coral associations of Cape Ghir (Atlantic High Atlas, Morocco) revealed highly diverse coral assemblages characterizing three reef environments, each of them dominated by one of the following genera: Dimorpharaea, Microsolena, and Stylina. A fourth assemblage is characterized by nerinean gastropods and stromatoporoids. Combined GPS surveys, 3D representation, and facies distribution studies permitted to understand the geometry of this coral reef within a particular tectonic setting. The reef became installed on top of a tilted block of Jurassic age subsequently folded into an east–west-trending anticline near the village of Tighert, exhibiting a 5 to 10° northward dip of its northern flank near the lighthouse of Cape Ghir. We suggest that the different fossil assemblages encountered in the field belong to one and the same fossil reef tract (within a unique facies model). The previously reported hypothesis of two successive reef horizons representing different biochrons is abandoned.