Sedimentological characterization and provenance analysis of the pre-collisional Betic & Rif turbidite systems
Final Report Abstract
The project, although its implementation faced some difficulties (i.e. the Covid pandemic, as well as the original PhD student), lead to the following main results: For turbidite systems of the Mauretanian and Mixed subdomains four lobe subenvironments (i.e. Lobe axis, Lobe off-axis, Lobe fringe and Distal fringe) could be differentiated, with vertical stacking sequences indicating predominant lobe patterns reflecting aggradation and/or lateral shifting of lobes. Development of the lobe depositional systems was related to autogenic processes. The sediments of these subdomains clearly reflect the exhumation of the Alpine orogenic units at the northern basin margin. Pre-orogenic sediments are generally siliciclastic (Lower Cretaceous to Upper Cretaceous-?Paleocene sediments), which contrasts carbonate-dominated sediments from the Eocene (intraarenites and hybrid arenites; erosion of carbonate platforms after exposition due to sea level changes and/or differential uplift of basin margin areas). From Oligocene times onwards, deposition was syn-orogenic – with siliciclastics changing from primarily low-grade metamorphic and sedimentary (Malaguide-Ghomaride realm and the associated Frontal/Dorsale units), as well as volcanic lithics to higher-grade metamorphic material and plutonic clasts (from an older Malaguide-Ghomaride basement or a lost area of Calabria- Peloritani-Kabylia –type crust. In Burdigalian times, the Alpujárride-Sebtide Complex contributed to the supply of the basin. Compositional differences were observed both from petrographic and geochemical datasets. Ichnofaunas in both Spanish and Moroccan Mauretanian and Mixed deposits were broadly similar, with only some ichnofaunal elements (i.e. from the Ophiomorpha rudis subichnofacies) being more common in the Spanish deposits (implying local variations influencing general parameters). The general ichnodiversity (including that of graphoglyptids) was particularly high in Eocene times. A post-Eocene period decline in ichnodiversity correlates well with changes in global oceanographic and climatic conditions at the transition from the Eocene to the Oligocene period, which involved a general cooling (also in deeper waters) and a concomitant change from an oligotrophic to a eutrophic regime. The Numidian Formation in both Spain and Morocco during Early Burdigalian times was described in detail, showing a lower slope (channel) – lobe transition setting. A channel could only be defined in Morocco, while Spanish (and other Moroccan) outcrops examined, showed proximal to medial lobe axis or off-axis settings, or, more rarely, channel margin settings. Deposition was from both intrabasinal and extrabasinal turbidites, as well as sandy debris flows. Petrographic and geochemical analyses were used to define the sediment composition of the Numidian sandstones providing, for the first time, published quantitative petrographic (and also geochemical) data from Spain and expanding on the sparse data from Morocco. Spanish Numidian sandstones (Q86-99,F1-14,L0-1) showed a greater feldspar component, than the Moroccan Numidian sandstones (Q94-99,F1-6,L0).
Publications
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Oldhamiafrom the Oligocene/Miocene-age deep-marine Algeciras Unit, Campo de Gibraltar Complex, southeast Spain: First record of this characteristic Lower Palaeozoic (mainly Cambrian) ichnofossil from younger strata. Ichnos, 28(3), 217-230.
McCann, Tom
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A deep-marine ichnofossil assemblage from the Tertiary-age Algeciras Formation and related units, Campo de Gibraltar Complex, Southern Spain. Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, 174(4), 745-789.
McCann, Tom
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An unusual occurrence of armoured mud balls from a deep-marine succession, Numidian Formation, NW Morocco. Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen, 309(3), 255-271.
Koch, Heike & McCann, Tom
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Sedimentology of the Beni Ider and associated Talaa Lakrah turbidite successions of the Maghrebian Flysch Basin (Northern Rif, Morocco). Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen, 312(2), 215-241.
Koch, Heike & McCann, Tom
