Terra Nova, 00, 1–9, 2010 Abstract The ultimate source of the deepwater Numidian Flysch sediments has long been a matter of controversy. Did the sediments of this late Cenozoic orogenic belt in the western Mediterranean derive from a European or African source, or from a combination of the two? New data presented here strongly favour a European provenance. Zircon ages of 514 ± 19 Ma from Tunisia and 550 ± 28 Ma from Sicily can only have derived from rocks of European affinity. These zircons have been separated from quartz‐rich sandstones with a distinctive, highly mature heavy mineral assemblage that is different from those of North African autochthonous formations. The mature petrography and dominance of euhedral prismatic zircon grains indicate a medium to high‐grade metamorphic source. Most palaeocurrent data are indicative of flow from the N and NW. The original European provenance is most likely now represented by predominantly metamorphic rocks of the Kabylie belt in northern Algeria, as a result of microplate movement and thrust emplacement.
Structural interpretations of seismic sections crossing the Tell area in Tunisia, allow us to outline the structural style of the subsurface along the thrust front of the Numidian ''nappe'' and its relationships with the substratum north of the Middle Mejerda valley. The seismic interpretations show a structural style characterized by large thrust sheets detached over the Triassic salt, whereas the autochthonous cover is affected by inherited faults and tilted blocks. These inherited faults are connected at depth on the major ''décollement'' level represented by the interface Triassic salt/Mesozoic-Cenozoic cover. This autochthonous Atlas type cover recorded the Eocene Atlas compressional event outlined by the angular unconformity of the Oligo-Miocene on top of folded Cretaceous strata. Seismic interpretation shows also the occurrence of important halokinetic movements deforming both the autochthonous and allochthonous series. Two types of diapirs can be distinguished: the first ones cutting the autochthonous sedimentary cover, the second ones the Tellian sheets specially the Numidian ''nappe'' which is the uppermost tectonic unit of the Tellian belt. These latter Triassic levels have pierced the allochthonous cover after the ''nappes'' emplacement i.e. after the Langhian and during the Late Miocene compressional events. Otherwise, Triassic salt is incorporated as sole thrust level beneath the Numidian ''nappe''. A regional structural transect crossing the whole Tunisia thrust belt from the Tell to the southeastern foreland and the Zaghoaun thrust-fault allows us to illustrate the overall structural style of the Domain. It outlines the occurrence, beneath the upper-most Tellian structural level (Numidian) of imbricated units issued from duplexing of the sedimentary cover. It appears that the Numidian ''nappe'' detaches over Middle-Late Eocene shales which represent the upper-most ''décollement'' level. The Triassic salts locally exposed at the base the Numidian ''nappe'' are incorporated mechanically during the southward gliding of the ''nappe'' above the duplex structures.
The Cutri Formation's type location exposed in the NW of Mallorca, Spain, has previously been described and further interpreted as a base-of-slope carbonate apron. Incorporating new field and laboratory analysis this paper enhances this interpretation. From this analysis, it can be shown without reasonable doubt that the Cutri Formation was deposited in a carbonate base-of-slope environment on the palaeowindward side of a Mid-Jurassic Tethyan platform. Key evidence such as laterally extensive exposures, abundant deposits of calciturbidtes and debris flows amongst hemipelagic deposits strongly support this interpretation.Keywords: calcilturbidite, debrite, Bositra, Jurassic, Mallorca, base-of-slope apron Resumen La Formación Cutri, en su localidad tipo en el noroeste de Mallorca (España), ha sido previamente interpretada como un posible prisma de talud carbonático. Esta interpretación es ratificada y pormenorizada en este trabajo con la incorporación de nuevos datos de campo y de laboratorio. El análisis realizado muestra que la Formación Cutri se depositó en la base del talud, en el lado de un ambiente carbonato de base de la pendiente a barlovento de una plataforma carbonatada tetisiana del Jurásico Medio. Esta interpretación está apoyada por extensos afloramientos de gran continuidad lateral, abundantes niveles de calciturbidtas y debris-flows entre los depósitos hemipelágicos.Palabras clave: calcilturbidita, debrita, Bositra, Jurásico, Mallorca, prisma de base de talud carbonático Journal of Iberian Geology 42 (1) 2016: [95][96][97][98][99][100][101][102][103][104][105][106][107][108][109][110][111][112]
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