Profile at Jebel Akenzoud (Dadès Gorges) where the Tagoudite, Tafraout and Azilal Fms can be seen. (B) Close-up view of the left side ooidal shoal with lateral accretions (white arrows). (C) Stratigraphic correlation. (D) Close up of the right side shoulder. (E) Close up on the erosion surface.
The Tagoudite Formation marks a major shift in Liassic sedimentation, replacing the carbonate turbidites of the Ouchbis Formation with mostly siliciclastic layers. These layers alternate between gray and green sandstone, sandy marls, and siltstones, forming sequences up to 20 meters thick.[4] They show a decrease in grain size and an increase in marl content from bottom to top, with features like ripple marks and laminations. Microscopically, the turbidites are mainly fine silt, with varying amounts of quartz, feldspar, and carbonate detritus, and occasional pyrite. This formation suggests an open marine environment with sediment interruptions and materials coming from distant areas. It is widespread in the Central High Atlas, with thicknesses reaching up to 320 meters, and varies across different regions like Tounfite and Beni Mellal. In the Central Middle Atlas, sedimentation was interrupted by emersion before the formation's deposition.[4] The deposits of the Tagoudite Formation are mostly restricted to the central High Atlas, with a thickness of approx. 200 m in the northwest vs at 30–70 m in the southeast, but retaining around 200 m at center areas like Foum Tillicht.[5] More at the E it starts to disappear like at the Cirque de Jaafar, SW of Midelt or more at the E at Bou Redine Gorges, were the Agoudim Formation directly overlies the Pliensbachian.[6]
Small (-1 cm) rounded ridges and troughs wrinkle structures occur on the tops of fine-grained turbidite beds deposited rapidly in deep, low-light conditions, too deep for photosynthetic mats.[7] The wrinkles were likely formed by chemosynthetic microbial mats, sulfur-oxidizing bacteria (Beggiatoaceae, Thioploca spp., and similar Gammaproteobacteria) that thrive in dark, organic-rich sediments where chemical gradients provide energy. Frequent turbidity currents, high organic content (including woody debris), and sulfide-rich pore waters created ideal conditions for these mats to grow and for their textures to be preserved. Low animal activity due to toxic sulfide levels further enhanced preservation.[7]
Phytoclasts, spores, pollen and Tasmanites & Botryococcus algae indicate that the palaeoenvironment of the lower Toarcian Amellago area was likely proximal continental shelf with a high terrestrial input, and notorious influence of brackish water in the depositional environment.[42] This interval is numerically dominated by Classopollis, which usually accounts for more than 60.95% of the palynomorphs present.[42]
