Fernando Pérez-Valera

Nautiloids from the Muschelkalk facies of the Southiberian Triassic (Betic Cordillera, southern Spain)

The study of Middle Triassic (Ladinian) nautiloids from three successive ammonoid zones, and two sub-zones, of the Southiberian Triassic Muschelkalk facies (Betic Cordillera, southern Spain) has allowed the identification of the following species: Mojsvaroceras haasi Parnes, 1986, M. kummeli Parnes, 1986, Germanonautilus bidorsatus (von Schlotheim, 1820), G. tridorsatus (Böttcher, 1938), Grypoceras? quadrangulum (Beyrich, 1866a), Indonautilus awadi Kummel, 1960, I. privatus (Mojsisovics, 1882) and Picardiceras picardi Parnes, 1986. The possibly endemic Indonautilus innocens sp. nov. is described herein. Although some of these species have already been reported from the Betic Cordillera, most are described in detail and illustrated for the first time and their stratigraphical distributions determined accurately for this region. Of the nine nautiloid species described herein, five are known from the Germanic and Tethyan provinces and four are restricted to the Sephardic Province. The genus Picardiceras is typical of the Sephardic Province. It appears that during the Ladinian the Betic Cordillera was a palaeogeographical region for faunal exchange between Central Europe, North Africa and the Middle East. http://zoobank.org/urn:lsid:zoobank.org:pub:98032616-2778-439B-B6D4-D32BFF7CCB83

An evaporite‐bearing accretionary complex in the northern front of the Betic‐Rif orogen

The Guadalquivir Accretionary Complex forms a largely oblique prism at the northern edge of the Betic-Rif orogen, where Miocene sediments plus allochthonous evaporite-bearing units were accreted during the displacement of the Alboran Domain towards the west. Traditional interpretations end the tectonic structuring of the Betic Cordillera at the present topographic front, beyond which gravitational and/or diapiric processes would predominate. However, this study shows pervasive tectonic deformation in the outer prism with coherent oblique shortening kinematics, which is achieved through an alternation of roughly N-S arcuate thrust systems connected by E-W transfer fault zones. These structures accord well with the geophysical models that propose westward rollback subduction. The main stage of tectonic activity occurred in the Early–Middle Miocene, but deformation lasted until the Quaternary with the same kinematics. Evaporite rocks played a leading role in the deformation as evidenced by the suite of ductile structures in gypsum distributed throughout the area. S- and L- gypsum tectonites, scaly clay fabrics, and brittle fabrics coexist and consistently indicate westward motion (top to 290°), with subordinate N-S contraction almost perpendicular to the transfer zones. This work reveals ductile tectonic fabrics in gypsum as a valuable tool to elucidate the structure and deformational history of complex tectonic melanges involving evaporites above the decollement level of accretionary wedges.