Tectono‐sedimentary evolution of the ‘Numidian Formation’ and Lateral Facies (southern branch of the western Tethys): constraints for central‐western Mediterranean geodynamics

Abstract

Terra Nova, 24, 34–41, 2012 Abstract The origin of the Numidian Formation (latest Oligocene to middle Miocene), characterized by ultra‐mature quartzose arenites with abundant well‐rounded frosted quartz grains, remains controversial. This formation, sedimented in the external domain of the Maghrebian Flysch Basin, displays three characteristic stratigraphic members with marked longitudinal (proximal–distal) and transverse (along‐chain) variations with palaeogeographical importance. The origin of the Numidian supply is related to the outward tectogenetic propagation when a forebulge evolved in the African foreland, leading to the erosion of African cratonic areas rich in quartzose arenites (Nubian Sandstone‐like). The ages of the Numidian Formation checked by Betic, Maghrebian and Southern Apennine data suggest a timing for the accretionary orogenic wedge, earlier in the Betic‐Rifian Arc (after middle Burdigalian), later in the Algerian‐Tunisian Tell (after late Burdigalian) and afterwards in Sicily and the Southern Apennines (after Langhian). A geodynamic evolutionary model for the central‐western Mediterranean is proposed.

The Tell-Rif orogenic system (Morocco, Algeria, Tunisia) and the structural heritage of the southern Tethys margin

“…The basin is fed by immature turbiditic sandstones in the internal parts (Guerrera et al, 2005) and ultramature sandstones from the African craton in its external part (Belayouni et al, 2013;Guerrera et al, 2012;Guerrera and Martín-Martín, 2014;Thomas et al, 2010). The question of whether or not the Maghrebian Tethys was floored by an oceanic substratum is still open.…”

Geotechnical and landslide aspects in weathered granitoid rock masses (Serre Massif, southern Calabria, Italy)

“…These processes are closely related to the geodynamic and tectonic evolution of the Western Mediterranean area starting from the Permian-Triassic boundary (e.g., Guerrera et al, 2012;Alcalá et al, 2013;Perri and Ohta, 2014).…”

The Early Miocene “Bisciaro volcaniclastic event” (northern Apennines, Italy): a key study for the geodynamic evolution of the central-western Mediterranean

“…Palaeotectonic and palaeogeographic reconstructions of the central-western Mediterranean region during the Late Oligocene-Aquitanian and Burdigalian-Langhian times evidence the presence of a microplate (Mesomediterranean Microplate) located between the European and African Plates (Doglioni 1992;Guerrera et al 1993Guerrera et al , 20052012b; among others) and bordered northwards by a transform fault separating from the European margins (Guerrera et al 2012b;Alcalá et al 2013) and southward by another oceanic area called the Maghrebian Flysch Basin-Lucania Basin Perrone et al 2008;and references therein).…”

“…4) is estimated to be several hundred kilometres. Moreover, the epiclastic processes (turbidites) from Sardinia would have been prevented by the complex palaeogeography of the western Mediterranean region in the time span considered (Dewey et al 1989;Doglioni 1992;Guerrera et al 1993Guerrera et al , 2005Guerrera et al , 2012bMaillard and Mauffret 1993;de Capoa et al 2002;among others). A possible relationship with Sardinia volcanism can be invoked only for thin and very fine-grained volcaniclastic pelites (fallout processes) deposited between 22-20 and 17-13 Ma, when a large volume of ignimbrites and fallout deposits developed in Sardinia (Assorgia et al 1997).…”

“…On the basis of both transport and sedimentation processes recognized for the volcaniclastic sediments of the "Bisciaro volcaniclastic event", and the short distance and the palaeogeography between volcanic areas and the sedimentary basins , 2012b, Guerrera and Martin-Martin 2014Alcalá et al 2013), the main volcanism affecting the Bisciaro depositional area should probably be located along the external active margins of this Microplate and/or, in a late evolutionary stage, along the suture zone between the Adria Plate and the Mesomediterranean Microplate (Fig. 4) in a way different from that indicated previously by Critelli et al (2013) who located volcanic arcs only in Sardinia.…”