A Seismic Facies Analysis to Determine the Relative Age and History of the Al Idrissi Mud Volcano from Offshore Larache Located in the NW Moroccan Atlantic Margin

Formed on top of the Gulf of Cadiz, the Al Idrissi mud volcano is the shallowest and largest mud volcano in the El Arraiche mud volcano field of the northwestern Moroccan margin. The development and morphology of mud volcanoes from the El Arraiche mud volcanoes group have been studied at a large scale. However, the time interval related to their formation period still needs to be better understood. In this regard, we interpreted and analyzed the seismic facies from the 2D reflection data of the GEOMARGEN-1 campaign, which took place in 2011. The aim was to identify the seismic sequences and draw the Al Idrissi mud volcano system to determine the formation period of the Al Idriss mud volcano. And as a result, the Al Idrissi mud volcano system is made of both buried and superficial bicone and was identified along with the Upper Tortonian to Messinian-Upper Pliocene facies. As the initial mud volcano extrusive edifice, the buried bicone was formed in the Late-Messinian to Early-Pliocene period. However, the superficial bicone, as the final extrusive edifice, was included in the Late Pliocene. In this case, the timing interval between the buried and superficial bicone is equivalent to the Late-Messinian to Upper-Pliocene period. Therefore, the latter corresponds to the Al Idrissi mud volcano formation period.

Preliminary Palynostratigraphic Data on the Middle Albian-Lower Cenomanian of the Tarfaya Basin, Southwest Morocco

The Tarfaya-Laayoune-Boujdour basin is of great interest to oil exploration;on this aspect, there has been exploration by the Moroccan National Office of Hydrocarbons and Mining, which has shown indices of oil and/or gas recorded in most wells drilled in the Moroccan Atlantic margin. FD-1 well, object of this study, is one of these wells located in the offshore Tarfaya-Laayoune-Boujdour basin. A palynological examination of the processed samples revealed the existence of organic palynomorphs, well conserved and rich in dinoflagellate cysts. The latter are composed of worldwide marker taxa of high stratigraphic resolutions. Thus, the middle upper Albian (3408 - 3408.5 m) is determined by the presence of Cribroperidinium tensiftense, Tehamadinium coummia, Spiniferella cornuta, Chichaouadinium vestitum, Dinopterygium alatum and Litosphaeridium arundum. The upper Albian (3406.5 - 3408 m) is characterized by the FOs of marker taxa: Cyclonephelium chabaca, Cribroperidinium auctificum and Chichaouadinium vestitum. Lastly, the upper Albian-lower Cenomanian transition is defined between 3404 m and 3406.50 m, as suggested by the FOs of Chichaouadinium boydii, Dinopterygium tuberculatum, Sepispinula ancorifera, Litosphaeridium conispinum, Prolixosphaeridium conulum and Xenascus ceratioides.

Seismic Signature Analysis for Clarification of Mud Volcanoes from the New Mud Diapirs Discovered at the NE-SW Moroccan Atlantic Margin

Our aim is to clarify mud volcanoes from the new mud diapirs resulting from the seismic attributes analysis applied to the low resolution Burmah oil “1973-1974” seismic data. The latter was carried out on the Larache and Tanger-Larache offshores from the NE-SW Atlantic margin. The high resolution seismic data was essential for this evaluation. In this case, we applied seismic signature analysis to four seismic profiles from the map of the seismic data set, which includes all new mud diapirs. This helped us to classify different types of mud diapirs within the seismic profiles. And as a result, six deep mud diapirs from the Prerifaine Nappe of Morocco, a shallow mud diapir, and four seafloor-piercing mud diapirs have been observed. Furthermore, the seafloor-piercing mud diapirs show a mushroom-shaped and conical-shaped cone. As they break through the seafloor, these kinds of cones characterize mud volcanoes. In this case, we may conclude that the resultant seafloor-piercing mud diapirs are likely to be mud volcanoes. However, more geological sampling and seafloor observation are still required.

Meso-Archean to Mid-Paleozoic Granitoids in Oulad Dlim Massif(the Pericratonic Terrane of the Reguibat Shield,West African Craton,Morocco):Petrology,Geochemistry,Geochronology and Geological Implications

The Oulad Dlim Massif,adjacent to the Reguibat Shield in South Morocco was considered up to now as part of the Variscan belt(Mauritanides)with a polyphase geologic history and a complex geodynamic evolution implicating oceans closures and accretion of exotic terranes(Avalonian and Meguman)during the Variscan-Alleghanian orogeny.The use of modern technology to characterize the petrology,the geochemistry and the geochronology of the lithological units forming this region,combined to field surveys has led to an updated geological architecture and different geological history.The Oulad Dlim Massif is mainly a deformed Archean terrane,as recorded by its eastern and western sectors,dominated in its central part by a bimodal felsic-mafic magmatism forming the Ediacaran sector.The study of these magmatic complexes supports strongly the intracontinental origin of this bimodal magmatism vs.the oceanic origin published before in literature.The exploration of this massif conducted also to the identification of a Silurian-Devonian sector in the western part.Therefore,up to date,different magmatic events lasting from the Meso-Archean to the Cretaceous are recorded in the Oulad Dlim Massif rocks,among them different generations of granitoids are reported.New data on granitoids from the Ediacaran sector are presented in this paper.This recent data demonstrates that Oulad Dlim Massif has been affected by the main Ediacaran–Cambrian extensional event widely documented in other structural domains of Morocco and other parts of North Gondwana.Additionally,the study of the Silurian-Devonian sector rocks highlighted the presence of a Caledonian tectonic event challenging the ideas about the paleogeography of this part of northwestern Africa and its geological evolution during the Paleozoic.However,despite the significant contribution of this extensive survey and the abundance of data on the Oulad Dlim Massif,more studies are required to reconstruct the puzzle at plate tectonic scale.