Givetian rugose corals from the Zemmour in Mauritania

Abstract

1. Introduction The Givetian of the Zemmour is well exposed to the north of Bir Moghreim (formerly Fort Trinquet), in the northern part of Mauritania (Fig. 1). It was investigated in great detail, from a lithologic and biostratigraphic point of view, by Sougy (1964) who gathered among others a large collection of rugose corals in the early Sixties. Part of these specimens was sent to Professor Marius Lecompte of the Catholic University of Louvain in Belgium and is now stored in the Collection of Palaeontology of the Institut royal des Sciences naturelles de Belgique at Brussels. Three Givetian species of massive rugose corals have been identified in the Zemmour by Coen-Aubert (2013); these are Phillipsastrea torreana (Milne-Edwards & Haime, 1851), P. kergarvanensis Coen-Aubert & Plusquellec, 2007 and P. sobolewi (Rozkowska, 1956). Besides two massive colonies belonging to Argutastrea Crickmay, 1960 and Iowaphyllum Stumm, 1949, a diverse fauna of mostly solitary rugose corals is described in this paper. Unfortunately, the Givetian of the Zemmour is not dated or subdivided with much precision as there are nearly no recent studies on other groups of fossils and as there are no block samples available for the extraction of microfossils such as conodonts. Figure 1. General setting in Northwestern Africa. 2. Geological setting and material The Givetian of the Zemmour has been summarized with some detail by Coen-Aubert (2013), on the basis of the three main sections investigated by