SEDIMENTOLOGY AND ICHNOLOGY OF THE LATE TRIASSIC IROHALEN MUDSTONE, ARGANA VALLEY, MOROCCO

Abdelilah Tourani (1) , Naima Benaouiss (1) , Sylvie Bourquin (2) , Jean Broutin

1 Département de Géologie [FSSM]
2 GR - Géosciences Rennes

The Late Triassic Irohalen Mudstone is 500 m in thickness and is laterally continuous in outcrop within Argana valley, Western High Atlas, Morocco. This mudstone-dominated unit rests conformably on the Agelgal sandstone and represents the upper part of the Timezgadiouine Formation. It comprises two fining-upward and coarsening-upward alluvial plain sequences that are accumulated under semi-arid climate. The two sequences are represented by (1) Lower Irohalen Mudstone and (2) Upper Irohalen Mudstone. It is composed predominantly of floodplain siliciclastic mudstones with interbedded proximal crevasse splay sandstones that evolve laterally into extensive floodplain siliciclastic mudstone, ephemeral lacustrine carbonate mudstones and distal crevasse splay siltstones. Channel sandstones and levee siltstones are also present. The lower Irohalen Mudstone has yielded a low diversity and abundant invertebrate and vertebrate ichnofossils. The invertebrate ichnofossil assemblages include Scoyenia, Cruziana, Rusophycus, Taenidium and Fuersichnus. The vertebrate ichnofossils consist of the lacertoide ichnogenus Rhynchosauroides, the dinosaurian ichnogenus Grallator, and the chirotherian ichnogenus Brachychirotherium. The purpose of this contribution is to describe the facies and associations of facies constituting the lower Irohalen Mudstone and to review these vertebrate and invertebrate ichnofossils and discuss their occurrence in a sedimentological and paleoenvironmental context.

Domains: Stratigraphy; Paleontology

Abdelilah Tourani, Naima Benaouiss, Sylvie Bourquin, Jean Broutin. SEDIMENTOLOGY AND ICHNOLOGY OF THE LATE TRIASSIC IROHALEN MUDSTONE, ARGANA VALLEY, MOROCCO. International Meeting of Sedimentology 2017, Oct 2017, Toulouse, France. pp.892, 2017, Abstract book. ⟨insu-01718235⟩