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The Skoura inlier in the Moroccan High Atlas consists of thick Precambrian–Paleozoic formations. It displays, in the western part near Aguerzega village, a volcano-sedimentary succession of about 400 m thickness. It includes a variety of welded and non-welded ignimbrites, lapilli-tuff fallout deposit, coherent lava, sedimentary mass flow deposit and fluvial sediments, which are grouped into three lithofacies associations, corresponding to different depositional environments. The volcanic activity in the studied area represents successive volcanic eruptions, alternating with phases of quiescence (sedimentary beds). The Ediacaran volcano-sedimentary succession of the Skoura inlier represents an evolution in four stages in a subaerial environment. The geochemical results obtained from Skoura volcanic rocks display high silica-rich composition ranging from dacite to rhyolite. Major and trace elements show high-K calc-alkaline and alkali-calcic to alkaline affinities and reflect an active continental margin signature. In addition, the studied rocks show enriched LILE compared to HFSE with negative Nb-, Ta- and Ti anomalies. This is consistent with a post-collisional setting, documented for the final phase of the Pan-African orogeny. Laser ablation U–Pb zircon dating on three rhyolitic ignimbrites from the base and top of two profiles, yielded ages of 580 ± 7 Ma, 574 ± 14 Ma and 571 ± 4 Ma. These ages compare well with the lower Ouarzazate Supergroup, widespread in the Anti-Atlas, as well as in the High Atlas and with rare exposures in the Meseta domain in northern Morocco. [ABSTRACT FROM AUTHOR]

A multidisciplinary approach based on lithostratigraphy, petrography, modal composition and geochemistry was performed for the first time, to study the Early Ediacaran Skoura Turbidites (EEST) of the Skoura inlier, Central High Atlas. It represents widely distributed turbidite successions up to 8 km in thickness. A total of twelve lithofacies types have been distinguished, spread in four profiles, and grouped in three major depositional environments: shallow delta complex (FA1), submarine channel (FA2), and deep-sea fan (FA3). The paleogeographic distribution of the EEST may indicate basin depth changes related to the onset of convergence. Petrographic and modal analyses of EEST reveal greywacke and lith-arenite lithologies displaying similar clast composition, mainly comprising quartz and lithic fragments. Volcanic, plutonic, and metamorphic rocks have been exposed in the source areas feeding the Skoura basin. On Q-F-L diagram, EEST have characteristics of a recycled orogen, suggesting their derivation from an active arc setting. Geochemical data of EEST samples display similar SiO 2 and Al 2 O 3 abundances, with relatively intermediate compositions. Most of the studied samples demonstrate their derivation from a composite of oceanic island and continental arc systems providing felsic and mafic to intermediate detritus to the Skoura basin. Rare-earth element patterns show features similar to those of sandstones in modern active margin zones. The EEST rocks are similar with other Early Ediacaran sediments of the Saghro Group in the Anti-Atlas belt. This architecture suggests deposition of the EEST in an orogenic basin developed in a back-arc setting during the Early Ediacaran time. • Deep sea and shallow marine environments for the Early Ediacaran turbiditic rocks in the Skoura inlier. • Stratigraphic and geochemical features of the Skoura Turbidites are linked to back arc setting. • Geochemical characters of the Skoura Turbidites indicate a mixture of felsic and mafic sources. • The Skoura Turbidites line up with the Early Ediacaran geodynamic evolution at the Northwestern Gondwana margin. [ABSTRACT FROM AUTHOR]

Various forms of volcanism occurred during the Middle Cambrian southeast of the Ougnat inlier in the eastern Anti-Atlas of Morocco. This study is the first to examine the formation of these volcanic deposits and interrelationships to the sedimentary host and tectonics on local and regional scales. The emplacement history of the volcanosedimentary succession of Ouinguigui has been characterised by a multi-disciplinary approach of field work, facies analysis of the volcanic rocks and their host and by geochemical analysis of coherent volcanic rocks. Additionally, we introduce a generic facies code system for subaqueous to emergent basaltic successions to make related deposits more comparable. The sedimentary host rock is composed of pre-transgressive conglomerates and sandstones of the Tikirt and Akerouz Member, which are interpreted as deposits of shelf-type fan-delta and shoreface deposits. The transgression is reflected by an abrupt decrease in grain size and the presence of packstones similar to the Micmacca Breccia Member. The post-transgressive clastic deposits of the Feijas Internes Group and Tabanit Group are the main host for the volcanic activity. They are composed of coarsening-upward sequences, which reflect gradual transitions from offshore to shoreface and foreshore facies. The alkaline volcanism comprises four main phases, which are induced by the SW-vergent tilting of a basement block during extensional tectonics. Phase I starts with the emplacement of diatremes within the Jbel Wawrmast Formation and Jbel Afraou Formation reaching an estimated depth of ca. 200 m. They are the result of phreatomagmatic eruptions caused by the rise of basaltic magma into the coastal environment of the host. Phase II is characterised by the emplacement of large volumes of basaltic lava through fissure eruptions and the formation of a lava delta in the eastern part as well as subaqueous to emergent phreatomagmatic volcanism in the middle and western part of the Ouinguigui area. Wave activity led to the formation of volcanogenic conglomerates and sandstones. Phase III and IV are reflected by the emplacement of subvolcanic intrusions consisting of trachy andesites and trachytes. Whole rock geochemical data of 13 samples confirm the alkaline character of the Ouinguigui magmatism, which derived from a garnet lherzolite source of within-plate volcanism. • Detailed facies analysis of a marine to emergent Middle Cambrian volcanic complex in the eastern Anti-Atlas, Morocco. • Phreatomagmatism, Strombolian fountaining, lava-delta forming eruptions, and subsequent intrusion like plugs and laccoliths. • Multi-phased alkaline volcanism (basalt, trachy andesite and trachyte) from a garnet-bearing lherzolite mantle source. • SW-vergent tilting of a basement block between the Oued Smile and the South Oukhit fault related to Cambrian rifting. [ABSTRACT FROM AUTHOR]