Environmental study of coral assemblages from the upper Viséan Tizra Formation (Adarouch area, Morocco): implications for Western Palaeotethys biogeography

Abstract

The Tizra Formation located in the northern part of the Azrou-Khenifra region, northcentral Morocco provides excellent material for studying the environmental implications on coral assemblages, because it represents sedimentation of complex mixed carbonate and siliciclastic rocks with different platform settings. Six different coral assemblages are described and their relationships with environmental factors are analysed. The analysis of coral assemblages allows to identify the sedimentation of the Tizra Formation in a complex platform/ramp with the development of microbial mounds and strong compartmentalisation that produces diverse ecological niches for the development of corals. Comparison of the assemblages from the Tizra Formation with other areas from the Western Palaeotethys (British Isles, SW Spain and other assemblages in North Africa) shows high similarities between all of them. However, some peculiarities occur in the Tizra Formation, where the shallowwater coral assemblages show higher diversity, but deeper-water coral assemblages from Adarouch show lower diversity than those in northern European areas. Partial geographic isolation of the Adarouch-Khenifra region and/or latitudinal differences with the Western European region seem to be the main reasons for these differences.