Punctuated Neogene tectonics and stratigraphy of the African-Iberian plate-boundary zone: concurrent development of Betic-Rif basins (southern Spain, northern Morocco)

Abstract

The geological configuration of the present-day Mediterranean is characterized by a complex and extensive system of both interconnected and fragmented fold-and thrust belts that is associated with back-arc basins (e.g. Carminati et al., 1998;Rosenbaum & Lister, 2004). Their tectonic structure and setting are varied, and the compressional origin and growth of the different belts and the formation of the adjoining extensional basins also varies considerably in age. The different fold-andthrusts belts did not evolve during one single, uninterrupted cycle of Alpine orogenesis, but are the ultimate outcome of a prolonged, polyphase process of intermittent plate-tectonic interaction between the African-Arabian and Eurasian plates. This resulted in the creation and ultimate disappearance of two major oceanic basins, the Palaeotethys (mainly Palaeozoic) and the Neotethys (late Palaeozoic-Mesozoic). As in the preceding Jurassic and Cretaceous times, the motions of Africa-Arabia relative to Eurasia during the Tertiary were an important control on the geological evolution of the Alpine Tethys (late Mesozoic-Tertiary). Various kinematic frameworks for palaeotectonic and palaeogeographic reconstructions have been proposed for the region (e.g. Dewey et al., 1989;Rosenbaum et al., 2002). These were mostly based on analysis of rotation parameters (poles of rotation, rotation angles), which allowed to constrain past relative velocities between Africa and Eurasia. In addition, analysis of North Atlantic magnetic lineations helped to constrain the movement of Africa and Europe relative to North America. The consensus view is that during the Late Cretaceous Africa converged towards Europe in a S-N directed rotational mode. This was contemporaneous with spreading of the Azores part of the North Atlantic, the coeval opening of the Gulf of Biscay like a sphenochasm and the resulting anti-clockwise rotation of Iberia with respect to Eurasia. Sinistral motion occurred after an active plate boundary subject to left-lateral strike-slip faulting had been established at the northern margin of the Iberian block. Consequently, Iberia behaved like a promontory AbstractThis paper integrates the sequence stratigraphic and tectonic data related to the Neogene geodynamic and palaeogeographic development of the African-Iberian plate boundary zone between Spain and Morocco. Though the dating of individual tectonostratigraphic sequences and their delimiting sequence boundaries varies in accuracy and precision, their apparent correlation strongly suggests contemporaneous development of the Betic and Rif basins. This may likely be attributed to regional changes of the overall compressional intra-plate stress field. This, in turn, was governed by coeval plate-kinematic changes related to the ongoing collisional convergence of Africa and Iberia. The Neogene succession is characterised by brief tectonic pulses that governed the sequence stratigraphic development of the Betic-Rif basins (NBR phases). It broadly correlates with the coeval sequences in the ...

Miocene tectono-sedimentary evolution of the eastern external Betic Cordillera (Spain)

“…The foredeep evolution in the EBZ (ProtoGuadalquivir foredeep stage) is comparable with the evolution of other external sectors of the Rif (Figure 10 (B2)), Tunisian Tell (Figure 10(B3)), and northern Apennine (Figure 10(B4)) Chains (Belayouni et al, 2013;Guerrera, Tramontana, & Donatelli, 2012;Sissingh, 2008;Vera, 2000) that are related to the evolution of several micro-blocks (Alboran, Kabylides, Peloritani and Calabria) resulting from the fragmentation of the Mesomediterranean Microplate (Guerrera & Martín-Martín, 2014a; and references therein), whose Miocene orogenic evolution is schematized in Figure 10(A).…”

“…The comparison between the study area and other External Betic Zone sectors (Guerrera et al, 2014;Guerrera & Martín-Martín, 2014b;Sissingh, 2008;Vera, 2000) highlights a similar tectono-sedimentary evolution (Figure 10(B1)). Calcareous and marly formations representing the transition from an internalexternal platform realm to a basinal environment are widespread.…”

“…The Rif sector seems to show two transgressive-regressive cycles (Sissingh, 2008). The lower cycle (late Langhian to middle Tortonian) is represented by the Numidian, Lower Molasse, and Continental Clay Formations, while the upper cycle (late Tortonian-Messinian) consists of the Upper Molasse and Marine Marls Formations, deposited before the emersion.…”

“…Another common feature in the compared margins is the occurrence of olithostrome-like or 'salt glacier' deposits related to the overflow of Triassic terrains at different stratigraphic levels coming from the basal level of the stacked superficial nappes or from diapirs, being the latter the most common features placed in the late Miocene (Martín-Martín et al, 2018a, 2018bSissingh, 2008;Tent-Manclús et al, 2000).…”

“…In the region a Cretaceous tectonic inversion from extension to compression occurred, similarly to what was observed in the western Mediterranean Alpine chains (Guerrera et al, 2014;Guerrera & Martín-Martín, 2014a; and references therein). In the EBZ the Mesozoic normal faults evolved during the Tertiary under compressive deformation as strike-slip faults, and later as thrusts (Sanz de Galdeano & Buforn, 2005;Martín-Martín et al, 2018a;Martín-Martín, Guerrera, Alcalá, Serrano, & Tramontana, 2018b;Sissingh, 2008). In the Miocene many intramontane basins developed whose geometry and stratigraphic architecture were controlled by re-arrangements of blocks and faults.…”