Latest Ediacaran and Cambrian of the Moroccan Atlas Regions

TitleLatest Ediacaran and Cambrian of the Moroccan Atlas Regions
Publication TypeBook Chapter
Year of Publication2006
AuthorsGeyer, G, Landing, E
EditorGeyer, G, Landing, E
Book TitleMorocco 2006. Ediacaran-Cambrian Depositional Environments and Stratigraphy of the Western Atlas Regions. Explanatory Description and Field Excursion Guide
Series TitleBeringeria Special Issue
Series Volume6
KeywordsCambrian, latest Ediacaran, lithostratigraphy, Moroccan Atlas

The characteristics of the latest Ediacaran through Cambrian of the Moroccan Atlas regions are described and illustrated. Such major depositional controls as tectonic environments (a transtensional regime in this time interval) and eustatic changes that defined sequence boundaries and „Grand cycles,“ as well as a progressive southerly movement of the West Gondwanan margin that led to the loss of tropical carbonate platform facies and their replacement by siliciclastic-dominated successions in the Lower–Middle Cambrian boundary interval, are discussed briefly. The lithostratigraphic units for the uppermost Proterozoic(?) to the Upper Cambrian of the Moroccan Anti-Atlas and High Atlas mountains are reviewed and partly revised. The descriptions of lithostratigraphic units include lithology, depositional environments, fossil content, and synonymy. The Jbel Wawrmast Formation is divided into a lower Brèche à Micmacca Member and an upper Tarhoucht Member (new) that comprises the majority of the formation. The bio- and chronostratigraphy of the Atlas regions are summarized, and recently proposed, formal and informal biostratigraphical units of the Lower–Middle Cambrian are reviewed. Detailed stratigraphy allows recognition of diachroneity for several formational contacts. Controversial data and problems of the Moroccan Precambrian–Cambrian boundary are discussed in detail. The available evidence does not permit highly resolved certainty in correlations even at the stage-level with Lower Cambrian sections on other Cambrian continents. However, close similarities exist in the litho- and biostratigraphic developments of southern Morocco and Iberia, and demonstrate that both regions were coterminous on the West Gondwanan margin and geographically separated from the Avalon microcontinent by the latest Proterozoic.