Two Cenozoic Extensional Phases in Mallorca and Their Bearing on the Geodynamic Evolution of the Western Mediterranean

Abstract

We study the structure of the Llevant ranges in Mallorca with special emphasis on the Cenozoic extensional evolution of the island, which we integrate in a new geodynamic model for the Westernmost Mediterranean. Mallorca underwent two Cenozoic rifting phases in the Oligocene and Serravallian, before and after the development of its Foreland Thrust Belt (FTB). The first extensional event produced Oligocene semigrabens (≈29–23 Ma) that were inverted during the Early‐Middle Miocene (19–14 Ma) WNW‐directed FTB development. The second rifting event produced the extensional collapse of the Mallorca FTB during the Serravallian (≈14–11 Ma). This later rifting was polyphasic, with two orthogonal extensional systems, producing first NE‐SW, and then NW‐SE extension. The Oligocene extension affected a major part of the Western Mediterranean, opening the Liguro‐Provençal and other basins after the collapse of the Palaeogene AlKaPeCa orogen, and Mallorca, its former hinterland. Continued plate convergence nucleated a new subduction system in the Early Miocene that initiated along the Ibiza transform, producing the Mallorca WNW‐directed FTB and subduction of the South‐East Iberian passive margin. This process individualized the Betic‐Rif slab and initiated its westward retreat. Serravallian extension occurred at the northern edge of the subduction system coeval to the Algero‐Balearic basin opening. Extension initiated toward the SW direction of slab tearing and later rotated to a NW‐SE direction, probably in response to flexural and isostatic rebound. Through these processes the Alboran domain archipelago was driven toward the southwest until the Late Miocene, contributing to the present isolation of Mallorca from its Betic hinterland.

Back‐Arc Dynamics Controlled by Slab Rollback and Tearing: A Reappraisal of Seafloor Spreading and Kinematic Evolution of the Eastern Algero‐Balearic Basin (Western Mediterranean) in the Middle‐Late Miocene

“…Finally, whether the first basin formed at the rear of the southward rollback stage (i.e., 20‐16 Ma, Figure 12b) was continental or oceanic remains a subject of debate and needs further study (Do Couto et al., 2016; Platt et al., 2006; Platt & Vissers, 1989; Romagny et al., 2020; Moragues et al., 2021). This former back‐arc domain has been inverted later and may be seen as a continental‐type back‐arc basin at 18‐16 Ma (Moragues et al., 2021), that is, similar to the Aegean extensional domain, characterized by the development of extensional basins (Mascle & Martin, 1990) and by exhumation of metamorphic rocks by detachment faulting, a process controlled at first order by the southward Hellenic trench retreat (Brun & Sokoutis, 2010; Jolivet et al., 2013). The same question is posed regarding the present‐day WABB (Figures 12c and 12d).…”

“…Each proposed model inherently comes with its own assumptions, simplifications, and omissions, and therefore strongly differs from the others regarding the timing and chronology of opening of the AB sub‐basins and the position of the retreating subduction. These models can be classified into two major types with contrasting timing, that is, one‐step or two‐step models: one‐ one‐step opening by progressive SE‐directed rollback of the Tethyan slab (Schettino & Turco, 2006); modified from a previous simplified scenario such as the ones by (Gelabert et al., 2002; Gueguen et al., 1998; Jolivet & Faccenna, 2000), as well as the double‐saloon door opening proposed by (Martin, 2006); two‐ Diachronous opening model during Miocene times proposed by (Cohen, 1980; Driussi et al., 2015; van Hinsbergen et al., 2014; Mauffret et al., 2004; Moragues et al., 2021).…”

“…(2016), Millia and Torrente (2022) and Moragues et al. (2021). The arrows indicate the relative convergence between Africa and Eurasia from Bougrine et al.…”

“…In the central Mediterranean domain, the opening of the Tyrrhenian basin started in the late Miocene as a result of the south-east retreat of the Calabrian slab (Carminati, Wortel, Spakman, & Sabadini, 1998,b;Guillaume et al, 2010;Jolivet & Faccenna, 2000;Malinverno & Ryan, 1986;Prada et al, 2015). By contrast, the kinematic evolution of the Alboran (Al) and Algero-Balearic (AB) domains remains debated, with three main scenarios generally proposed: (a) fast and large (>600 km) westward motion of a rigid Al continental block allowing for the birth of the back-arc , Leprêtre et al (2018), Pellen et al (2016), Millia and Torrente (2022) and Moragues et al (2021). The arrows indicate the relative convergence between Africa and Eurasia from Bougrine et al (2019).…”

Numerical modelling of physical processes involved in the recycling of the lithosphere

“…The GWB is an open source software to easily build models of moderate complexity for geodynamic modelling. The details of the GWB file used to build the initial geometry can be found in the appendix D. Our model setup tries to reproduce the situation and geometry of the RGB slab at 20 Ma based on the most recent tectonic reconstructions (Romagny et al, 2020;G ómez de la Pe ña et al, 2021;Moragues et al, 2021) and the best geodynamic models of Chertova et al (2014a,b). At that time, the slab trench had already rotated completely to the southwest and was approximately at the same longitude as Almeria in these reconstructions.…”