The Iberian Variscan Orogen

Total Page:16

File Type:pdf, Size:1020Kb

The Iberian Variscan Orogen CHAPTER 1 THE IBERIAN VARISCAN OROGEN Aerial view of the tectonic repetition of limestone beds in the Láncara Formation, Primajas duplex structure of the Esla thrust (photo by J.L. Alonso) Martínez Catalán, J.R. Aller, J. Alonso, J.L. Bastida, F. Rocks of Upper Proterozoic to Carboniferous age - forming the Variscan or Hercynian orogen - crop out widely in the western part of the Iberian Peninsula, in what is called the Iberian or Hesperian Massif. These deformed rocks, often metamorphosed and intruded by different types of granitoids, were witness to the great mountain range formed in the late Paleozoic, basically in the Late Devonian and Carboniferous (between 370 and 290 million years ago), by the convergence and collision of two major continents: Laurasia and Gondwana. The Iberian Massif constitutes a geological framework of global interest. It is unique due to the continuity of its exposures and because it displays excellent records allowing the analysis of continental crust features, the tectonic, metamorphic and magmatic evolution of orogens, and therefore provides enormously relevant data about the lithospheric dynamics during the latest Precambrian and the Paleozoic. The Variscan orogen forms the basement of the Figure 1. Scheme showing the position of the Iberian Iberian Peninsula and of most of western and central Peninsula in relation to the Appalachians and the Europe. A crustal basement is the result of an orog- Caledonian and Variscan belts. Modified from eny, that is, the consequence of a deep remobilization Neuman and Max (1989). of the continental crust caused by the convergence of plates, and is associated to uplift and the creation of relief. The Variscan orogeny is the name given to formed at the end of the Paleozoic. In its place, what the whole set of geological processes which deeply presently is North America (then part of Laurentia) went modified the continental crust of western Europe and around the Variscan orogen and a wide belt developed the north and northwest of Africa during the Late along its eastern margin: the Appalachians. Paleozoic (Devonian-Permian). In its long period of activity (approximately 80 million years), this orogeny Figure 1 shows a paleogeographic reconstruction of shortened and intensely deformed those sediments the continental masses at the end of the Paleozoic. deposited previously along vast continental margins, It is noticeable how Iberia, the west of France and remobilized the prior basement on which they laid, the south of Great Britain used to occupy a key posi- generated a new crust by partial melting of the former, tion within the Variscan belt, at the junction of the added fragments of oceanic crust and mantle, eroded three most important Paleozoic orogenic belts: the and re-sedimented part of the newly formed crust, Appalachians to the southwest, the Caledonides to the and deformed the majority of the new sediments. northwest, and the Variscan to the northeast. Besides, Iberia shares with west France a marked and striking The importance of the Iberian Variscan orogen lies in its bend or curvature known as the Ibero-Armorican Arch location close to three big orogenic belts: Caledonian, (Ribeiro et al., 1995). Variscan and Appalachian. Given the diversity and quality of the outcrops, it is one of the key geologi- The former reconstruction allows to infer the ultimate cal frameworks recording the latest Precambrian and cause of the orogeny, since a set of continental crustal Paleozoic evolution of the planet, the deformation blocks are nearby but separated by orogenic belts. It is and generation of structures at different levels of the thus clear that convergence caused the orogenic pro- continental crust, the thermal history and the genera- cesses, and continental collision was the final result. tion of granitoids, all within the context of an active We are talking about the convergence of three large continental margin (latest Precambrian) and a conti- tectonic plates: Laurentia (North America), Baltica nental collision (Variscan Orogen). (Scandinavia, northern belt of Europe and Russia), and Gondwana (Africa, South America, Antarctica, India What crops out in the Iberian Peninsula from that and Australia). The final result was the creation, by basement (Iberian Massif) is part of a much longer the amalgamation of many continental masses, of a orogenic belt, extending to the north and east through supercontinent, in this case the last Pangea generated Central Europe into Poland, where it is shifted by a by the continuing geodynamics of our planet. tectonic line known as Thornqvist Fault, and continu- ing towards south Asia. Being such an old orogenic belt (its main development finished 290 million years ago), it is to be expected On the opposite side, the belt extends along north that the continental crust generated is already totally and northwest Africa parallel to the Atlantic margin. balanced (thermally and isostatically), and the orogenic However, the Atlantic did not exist when the belt was reliefs should have completely disappeared. However, 14 Martínez Catalán, J.R. – Aller, J - Alonso, J.L. and Bastida, F. Figure 2. Zonation of the Iberian Massif according to the subdivision proposed by Julivert et al. (1972). The red lines mark the position of the sections in figure 3. the subsequent history of the Iberian Peninsula origi- Peninsula, the different areas of the Massif will nated new reliefs, and that is what makes the Iberian be described according to the scheme proposed Variscan orogen even more interesting. by Julivert et al. (1972) (Figure 2). The five zones parallel and concentric to the Ibero-Armorican Arch As a matter of fact, the Iberian Peninsula did not even are: Cantabrian Zone, West Asturian-Leonese Zone, exist at the end of the Paleozoic, but was a later result Central Iberian Zone, Ossa-Morena Zone and South of the separation of the African and Eurasian plates. Portuguese Zone. The Iberian crustal block ended up with Eurasia in the first fragmentation (Middle Jurassic), but was later iso- The Galicia-Trás-os-Montes Zone of Farias et al. (1987) lated in the Early Cretaceous with the opening of the has also been added, although it is not a belt of the Bay of Biscay and the Pyrenean line, remaining at the orogen but an allochthonous crustal block thrusted mercy of both plates’ dynamics from then onwards, over the Central Iberian Zone. which began their convergence in the Paleocene and mid Eocene. This convergence, which is still active, Figure 3 shows two schematic sections through the deeply remobilized the Variscan basement in the Betic Iberian Massif, representative of the northwest (Pérez Range, and with less intensity in the Pyrenees, Iberian Estaún et al., 1991) and of the southwest (Simancas Range, Demanda Range, and several other modern et al., 2002) of the Iberian Massif. It can be noticed mountain ranges. Some of these mountain ranges that we are dealing with a belt with double centrifuge are aligned from east-northeast to west-soutwest vergence. (Cantabrian Range, Ancares, Montes de León, Central System and the Portuguese extension through Serra In the Iberian Massif there are several structures, da Estrela, Sierra Morena and many other minor which due to their geological interest together with reliefs) reflecting the north-south convergence of the the good exposure, have been chosen as Geosites: African and Eurasian plates, and resulting in excellent The Esla River Thrust in the Cantabrian Zone, the exposures of the Variscan basement. Mondoñedo Thrust in the West Asturian-Leonese Zone, Sierra del Caurel in the Central Iberian Zone, For a better presentation of the most outstand- and the Cabo Ortegal Complex in the Galicia-tras- ing features of the Variscan orogen in the Iberian os-Montes Zone (Figure 4). THE IBERIAN VARISCAN OROGEN 15 Figure 3, above. Two schematic geological sections across the Iberian Massif. a) According to Pérez-Estaún et al. (1991). b) According to Simancas et al. (2002). The location of the section is marked in figure 2. Figure 4, left. Geosites described in the text: 1) Esla River Thrust. 2) Sierra del Caurel. 3) Mondoñedo Thrust. 4) Cabo Ortegal Complex. Figure 5, below. Esla River Thrust section showing the main allochthonous units and duplexes, according to Alonso (1985). The Cantabrian Zone represents the Iberian Massif The Cantabrian Zone is the most continental part foreland: an area of Paleozoic pre-orogenic sediments of the Paleozoic basin and a magnificent example with relatively small thickness. These are Cambrian to of foreland thrust belt. In addition, it displays an Devonian shallow sea deposits, and display a wedging extremely tight tectonic bend representing the core of towards the external part as well as some stratigraphic the Iberian-Armorican Arch. discontinuities. This wedging is in part a result of crustal uplift followed by erosion in the late Devonian, Thin-skinned tectonics, the deformation style of the and shows the change from a passive margin to outer crust, features in the Cantabrian Zone a sequen- Variscan collision. This erosion was followed by basin tial development of thrusts and associated folds, con- deepening in the earliest Carboniferous, followed by temporaneous with the classic clastic wedges along synorogenic sedimentation. the front of major thrusts. It is also characterized by 16 Martínez Catalán, J.R. – Aller, J - Alonso, J.L. and Bastida, F. Figure 6. Esla River Thrust in the Valdoré tectonic window. The colored line shows the thrust plane. On top of it: limestones of the Láncara Fm, slates of the Oville Fm and quartzites of the Barrios Fm (Cambrian- Ordovician). Below, Upper Devonian limestones of the Portilla Fm and a thin succession of Lower Carboniferous. To the left, the layout of the Aguasalio syncline is observed. Figure 7. Esla River Thrust north of Valdoré. The thrust (upper colored line) superimposes with perfect parallelism Cambrian and Devonian layers.
Recommended publications
  • Sierra Morena De Córdoba Morena Sierra 23 1
    Sierra Morena de Córdoba Morena Sierra 23 1. Identificación y localización La Sierra Morena cordobesa es un territorio serrano con Los pueblos se integran adecuadamente en el paisaje, paisajes naturales muy antropizados para actividades de con sus ruedos, caseríos tradicionales e hitos religiosos agrosilvicultura, sobre todo ganaderas y forestales. La que dan jerarquía a la mirada sobre ellos. No existe una dehesa es el elemento paisajístico más significativo y tal capital de todo el ámbito, si bien hay numerosas pobla- vez el mejor ejemplo en el territorio andaluz del aprove- ciones que ejercen el papel de cabeza comarcal (Villanue- chamiento y uso sostenible de los recursos naturales. Las va del Rey, Villaviciosa de Córdoba, Fuente Obejuna). La sierras atraviesan la provincia de este a oeste, separando minería también ha dado centralidad y dejado paisajes la vega de Los Pedroches en un la zona oriental y cen- de gran interés en Peñarroya-Pueblonuevo. tral y prolongándose hacia el noroeste en el valle del alto Guadiato. Las formas suaves y acolinadas conforman el Esta demarcación se encuadra dentro de las áreas pai- paisaje del bosque aclarado y explotado de la encina y el sajísticas de Sierras de baja montaña y Campiñas de lla- alcornoque. nuras interiores. Reseñas patrimoniales en el Plan de Ordenación del Territorio de Andalucía (pota) Zonificación del POTA: valle del Guadiato-Los Pedroches, vega del Guadalquivir, centro regional de Córdoba y Montoro (dominio territorial del valle del Guadalquivir) Referentes territoriales para la
    [Show full text]
  • The North-Subducting Rheic Ocean During the Devonian: Consequences for the Rhenohercynian Ore Sites
    Published in "International Journal of Earth Sciences 106(7): 2279–2296, 2017" which should be cited to refer to this work. The north-subducting Rheic Ocean during the Devonian: consequences for the Rhenohercynian ore sites Jürgen F. von Raumer1 · Heinz-Dieter Nesbor2 · Gérard M. Stampfli3 Abstract Base metal mining in the Rhenohercynian Zone activated Early Devonian growth faults. Hydrothermal brines has a long history. Middle-Upper Devonian to Lower Car- equilibrated with the basement and overlying Middle-Upper boniferous sediment-hosted massive sulfide deposits Devonian detrital deposits forming the SHMS deposits in the (SHMS), volcanic-hosted massive sulfide deposits (VHMS) southern part of the Pyrite Belt, in the Rhenish Massif and and Lahn-Dill-type iron, and base metal ores occur at sev- in the Harz areas. Volcanic-hosted massive sulfide deposits eral sites in the Rhenohercynian Zone that stretches from the (VHMS) formed in the more eastern localities of the Rheno- South Portuguese Zone, through the Lizard area, the Rhen- hercynian domain. In contrast, since the Tournaisian period ish Massif and the Harz Mountain to the Moravo-Silesian of ore formation, dominant pull-apart triggered magmatic Zone of SW Bohemia. During Devonian to Early Carbonif- emplacement of acidic rocks, and their metasomatic replace- erous times, the Rhenohercynian Zone is seen as an evolv- ment in the apical zones of felsic domes and sediments in ing rift system developed on subsiding shelf areas of the the northern part of the Iberian Pyrite belt, thus changing the Old Red continent. A reappraisal of the geotectonic setting general conditions of ore precipitation.
    [Show full text]
  • Capítulo 7 LIBRO GEOLOGÍA DE ESPAÑA Sociedad Geológica De España Instituto Geológico Y Minero De España
    Capítulo 7 LIBRO GEOLOGÍA DE ESPAÑA Sociedad Geológica de España Instituto Geológico y Minero de España 1 Índice Capítulo 7 7- Estructura Alpina del Antepaís Ibérico. Editor: G. De Vicente(1). 7.1 Rasgos generales. G. De Vicente, R. Vegas(1), J. Guimerá(2) y S. Cloetingh(3). 7.1.1 Estilos de deformación y subdivisiones de las Cadenas cenozoicas de Antepaís. G. De Vicente, R. Vegas, J. Guimerà, A. Muñoz Martín(1), A. Casas(4), N. Heredia(5), R. Rodríguez(5), J. M. González Casado(6), S. Cloetingh y J. Álvarez(1). 7.1.2 La estructura de la corteza del Antepaís Ibérico. Coordinador: A. Muñoz Martín. A. Muñoz-Martín, J. Álvarez, A. Carbó(1), G. de Vicente, R. Vegas y S. Cloetingh. 7.2 Evolución geodinámica cenozoica de la Placa Ibérica y su registro en el Antepaís. G. De Vicente, R. Vegas, J. Guimerà, A. Muñoz Martín, A. Casas, S. Martín Velázquez(7), N. Heredia, R. Rodríguez, J. M. González Casado, S. Cloetingh, B. Andeweg(3), J. Álvarez y A. Oláiz (1). 7.2.1 La geometría del límite occidental entre África y Eurasia. 7.2.2 La colisión Iberia-Eurasia. Deformaciones “Pirenaica” e “Ibérica”. 7.2.3 El acercamiento entre Iberia y África. Deformación “Bética”. 7.3 Cadenas con cobertera: Las Cadenas Ibérica y Costera Catalana. Coordinador: J. Guimerá. 7.3.1 La Cadena Costera Catalana. J. Guimerà. 7.3.2 La Zona de Enlace. J. Guimerà. 7.3.3 La unidad de Cameros. J. Guimerà. 7.3.4 La Rama Aragonesa. J. Guimerà. 7.3.5 La Cuenca de Almazán.
    [Show full text]
  • Sierra Morena De Córdoba
    23 Castillo de los Blázquez Castillo de Ducado #0%2 %2 BLAZQUEZ VALSEQUILLO N-502 %2Castillo Junquilla PEÑARROYA-PUEBLONUEVO A-342 Cerro del Castillo#%20Castillo FUENTE OBEJUNA#0 BELMEZ %2Castillo de Viandar en el Hoyo Río Guadiato VILLANUEVA DEL REY Cerro del Castillo%2 ESPIEL %2#0Castillo de Sierra del Castillo N-432 %2Obejo#0 CENTRAL TERMICA Atalaya de Lara Castillo Vacar %2 %2 VILLAVICIOSA%2 DE CORDOBA Río Guadalmellato Castillo Nevalo ADAMUZ #0 Río Bembézar CERRO MURIANO JARAS (LAS) #0 SOL (EL) LAS ERMITAS Río Retortillo SANTA MARIA DE TRASSIERRA DÑA.MANUELA SERRANÍA DEL SOL Torre del Ochavo !. BRILLANTE (EL) Cigarra Baja CÓRDOBA !. CÓRDOBA HORNACHUELOS INJERTO (EL) #%20Castillo Castillo POSADAS %2ALMODOVAR DEL RÍO A-342 Río Guadalquivir ERMITAS CASTILLOS N ESCALA 1:500.000 TORRES - REFERENTES VISUALES RED FERROVIARIA RÍOS La Sierra Morena Cordobesa es un territorio serrano con paisajes naturales muy EJES PRINCIPALES antropizados para actividades de agrosilvicultura, sobre todo ganaderas y forestales. La dehesa es el elemento paisajístico más significativo y tal vez el mejor DEMARCACIÓN ejemplo en el territorio andaluz del aprovechamiento y uso sostenible de los recursos naturales. Las sierras atraviesan la provincia de este a oeste, separando la vega de Los Pedroches en un la zona oriental y central y prolongándose hacia el MEGALITISMO noroeste en el valle del Alto Guadiato. Las formas suaves y acolinadas conforman el paisaje del bosque aclarado y explotado de la encina y el alcornoque. MINERÍA Los pueblos se integran adecuadamente en el paisaje, con sus ruedos, caseríos ELEMENTOS DEFENSIVOS tradicionales e hitos religiosos que dan jerarquía a la mirada sobre ellos.
    [Show full text]
  • The Mediterranean Region—A Geological Primer
    160 Article by William Cavazza1 and Forese Carlo Wezel2 The Mediterranean region—a geological primer 1 Dept. of Earth and Geoenvironmental Sciences, Univ. of Bologna, Italy. [email protected] 2 Institute of Environmental Dynamics, University of Urbino, Italy. [email protected] The last twenty-five years of geological investigation of the Mediterranean region have disproved the traditional Introduction notion that the Alpine-Himalayan mountain ranges Many important ideas and influential geological models have been originated from the closure of a single, albeit complex, developed based on research undertaken in the Mediterranean oceanic domain—the Tethys. Instead, the present-day region. For example, the Alps are the most studied orogen in the geological configuration of the Mediterranean region is world, their structure has been elucidated in great detail for the most part and has served as an orogenic model applied to other collisional the result of the creation and ensuing consumption of orogens. Ophiolites and olistostromes were defined and studied for two major oceanic basins—the Paleotethys and the the first time in this region. The Mediterranean Sea has possibly the Neotethys—and of additional smaller oceanic basins highest density of DSDP/ODP sites in the world, and extensive within an overall regime of prolonged interaction research on its Messinian deposits and on their on-land counterparts has provided a spectacular example for the generation of widespread between the Eurasian and the African-Arabian plates. basinal evaporites. Other portions of this region are less well under- In greater detail, there is still some debate about exactly stood and are now the focus of much international attention.
    [Show full text]
  • Iberian Plate-Kinematics in Paleomagnetic and Mantle Reference Frames, Gondwana Research (2016), Doi: 10.1016/J.Gr.2016.03.006
    ÔØ ÅÒÙ×Ö ÔØ Cretaceous slab break-off in the Pyrenees: Iberian plate-kinematics in paleo- magnetic and mantle reference frames Reinoud L.M. Vissers, Douwe J.J. van Hinsbergen, Douwe G. van der Meer, Wim Spakman PII: S1342-937X(16)30053-3 DOI: doi: 10.1016/j.gr.2016.03.006 Reference: GR 1599 To appear in: Gondwana Research Received date: 21 September 2015 Revised date: 2 March 2016 Accepted date: 3 March 2016 Please cite this article as: Vissers, Reinoud L.M., van Hinsbergen, Douwe J.J., van der Meer, Douwe G., Spakman, Wim, Cretaceous slab break-off in the Pyrenees: Iberian plate-kinematics in paleomagnetic and mantle reference frames, Gondwana Research (2016), doi: 10.1016/j.gr.2016.03.006 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. ACCEPTED MANUSCRIPT Cretaceous slab break-off in the Pyrenees: Iberian plate- kinematics in paleomagnetic and mantle reference frames Reinoud L.M. Vissers1, Douwe J.J. van Hinsbergen1, Douwe G. van der Meer1,2, Wim Spakman1,3 1 Department of Earth Sciences, Utrecht University, Budapestlaan 4, Utrecht 3584 CD, Netherlands 2 Nexen Petroleum UK Ltd, 97 Oxford Road, Uxbridge, Middlesex UB8 1LU, UK 3 Center for Earth Evolution and Dynamics (CEED), University of Oslo, Sem Saelands vei 24, NO-0316 Oslo, Norway corresponding author: Reinoud L.M.
    [Show full text]
  • The Geology of England – Critical Examples of Earth History – an Overview
    The Geology of England – critical examples of Earth history – an overview Mark A. Woods*, Jonathan R. Lee British Geological Survey, Environmental Science Centre, Keyworth, Nottingham, NG12 5GG *Corresponding Author: Mark A. Woods, email: [email protected] Abstract Over the past one billion years, England has experienced a remarkable geological journey. At times it has formed part of ancient volcanic island arcs, mountain ranges and arid deserts; lain beneath deep oceans, shallow tropical seas, extensive coal swamps and vast ice sheets; been inhabited by the earliest complex life forms, dinosaurs, and finally, witnessed the evolution of humans to a level where they now utilise and change the natural environment to meet their societal and economic needs. Evidence of this journey is recorded in the landscape and the rocks and sediments beneath our feet, and this article provides an overview of these events and the themed contributions to this Special Issue of Proceedings of the Geologists’ Association, which focuses on ‘The Geology of England – critical examples of Earth History’. Rather than being a stratigraphic account of English geology, this paper and the Special Issue attempts to place the Geology of England within the broader context of key ‘shifts’ and ‘tipping points’ that have occurred during Earth History. 1. Introduction England, together with the wider British Isles, is blessed with huge diversity of geology, reflected by the variety of natural landscapes and abundant geological resources that have underpinned economic growth during and since the Industrial Revolution. Industrialisation provided a practical impetus for better understanding the nature and pattern of the geological record, reflected by the publication in 1815 of the first geological map of Britain by William Smith (Winchester, 2001), and in 1835 by the founding of a national geological survey.
    [Show full text]
  • Readingsample
    The TRANSMED Atlas. The Mediterranean Region from Crust to Mantle Geological and Geophysical Framework of the Mediterranean and the Surrounding Areas Bearbeitet von William Cavazza, François M. Roure, Wim Spakman, Gerard M. Stampfli, Peter A. Ziegler 1. Auflage 2004. Buch. xxiii, 141 S. ISBN 978 3 540 22181 4 Format (B x L): 19,3 x 27 cm Gewicht: 660 g Weitere Fachgebiete > Physik, Astronomie > Angewandte Physik > Geophysik Zu Inhaltsverzeichnis schnell und portofrei erhältlich bei Die Online-Fachbuchhandlung beck-shop.de ist spezialisiert auf Fachbücher, insbesondere Recht, Steuern und Wirtschaft. Im Sortiment finden Sie alle Medien (Bücher, Zeitschriften, CDs, eBooks, etc.) aller Verlage. Ergänzt wird das Programm durch Services wie Neuerscheinungsdienst oder Zusammenstellungen von Büchern zu Sonderpreisen. Der Shop führt mehr als 8 Millionen Produkte. Chapter 1 The Mediterranean Area and the Surrounding Regions: Active Processes, Remnants of Former Tethyan Oceans and Related Thrust Belts William Cavazza · François Roure · Peter A. Ziegler Abstract 1.1 Introduction The Mediterranean domain provides a present-day geo- From the pioneering studies of Marsili – who singlehand- dynamic analog for the final stages of a continent-conti- edly founded the field of oceanography with the publi- nent collisional orogeny. Over this area, oceanic lithos- cation in 1725 of the Histoire physique de la mer, a scien- pheric domains originally present between the Eurasian tific best-seller of the time (Sartori 2003) – to the tech- and African-Arabian plates have been subducted and par- nologically most advanced cruises of the R/V JOIDES tially obducted, except for the Ionian basin and the south- Resolution, the Mediterranean Sea has represented a cru- eastern Mediterranean.
    [Show full text]
  • 1. the Western Iberia Margin: a Geophysical and Geological Overview1
    Whitmarsh, R.B., Sawyer, D.S., Klaus, A., and Masson, D.G. (Eds.), 1996 Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 149 1. THE WESTERN IBERIA MARGIN: A GEOPHYSICAL AND GEOLOGICAL OVERVIEW1 L.M. Pinheiro,2 R.C.L. Wilson,3 R. Pena dos Reis,4 R.B. Whitmarsh,5 A. Ribeiro6 ABSTRACT This paper presents a general overview of the geology and geophysics of western Iberia, and in particular of the western Portuguese Margin. The links between the onshore and offshore geology and geophysics are especially emphasized. The west Iberia Margin is an example of a nonvolcanic rifted margin. The Variscan basement exposed on land in Iberia exhibits strike- slip faults and other structural trends, which had an important effect on the development, in time and space, of subsequent rift- ing of the continental margin and even perhaps influences the present-day offshore seismicity. The margin has had a long tec- tonic and magmatic history from the Late Triassic until the present day. Rifting first began in the Late Triassic; after about 70 Ma, continental separation began in the Tagus Abyssal Plain. Continental breakup then appears to have progressively migrated northwards, eventually reaching the Galicia Bank segment of the margin about 112 Ma. Although there is onshore evidence of magmatism throughout the period from the Late Triassic until 130 Ma and even later, this was sporadic and of insignificant vol- ume. Important onshore rift basins were formed during this period. Offshore, the record is complex and fragmentary. An ocean/ continent transition, over 150 km wide, lies beyond the shelf edge and is marked on its western side by a peridotite ridge and thin oceanic crust characterized by seafloor spreading anomalies.
    [Show full text]
  • Glenda Y. Nieto-Cuebas ISSN 1540 5877 Ehumanista/Cervantes 8
    Glenda Y. Nieto-Cuebas 215 The Sierra Morena Episodes in Don Quixote, from Prose to Visual Narrative Glenda Y. Nieto-Cuebas (Ohio Wesleyan University) The Sierra Morena episodes in Part One of Don Quixote have been deemed some of the most fascinating and experimental narratives in Early Modern Spanish prose due to their multiple narrators and the manner in which these narrative voices are integrated flawlessly into the main story (Mancing, 118). Frederick A. de Armas states that, with the transition into the Sierra Morena episodes, a drastic transformation takes place as Cervantes’s “narrative moves from a linear tale into a labyrinth where many mysteries and narrative threads appear” (96). Unfortunately, this labyrinthine quality makes it very difficult to represent this section of Don Quixote in alternative media, especially in visual narratives. As we know, there have been endless attempts to render parts of the Quixote in film, music, poetry, theater, illustrations, cartoons, comics, graphic novels, and more.1 While some have been more successful than others, few have captured the ingenuity and intricacy of Cervantes’s prose, nor its ability to actively engage its audience. This article focuses on how the narrative intricacies of these episodes have been successfully addressed in The Complete Don Quixote (2013), a graphic novel illustrated by Rob Davis. I analyze how its structural and compositional elements meet the demands of the original text, which compels readers to actively follow the characters along the bumpy roads of Sierra Morena. I begin by briefly outlining what the comic and graphic novel art forms involve, and how the academic community has received Davis’s work.
    [Show full text]
  • Mapping a Hidden Terrane Boundary in the Mantle Lithosphere with Lamprophyres
    ARTICLE DOI: 10.1038/s41467-018-06253-7 OPEN Mapping a hidden terrane boundary in the mantle lithosphere with lamprophyres Arjan H. Dijkstra 1 & Callum Hatch1,2 Lamprophyres represent hydrous alkaline mantle melts that are a unique source of information about the composition of continental lithosphere. Throughout southwest Britain, post-Variscan lamprophyres are (ultra)potassic with strong incompatible element enrich- 1234567890():,; ments. Here we show that they form two distinct groups in terms of their Sr and Nd isotopic compositions, occurring on either side of a postulated, hitherto unrecognized terrane boundary. Lamprophyres emplaced north of the boundary fall on the mantle array with εNd −1 to +1.6. Those south of the boundary are enriched in radiogenic Sr, have initial εNd values of −0.3 to −3.5, and are isotopically indistinguishable from similar-aged lamprophyres in Armorican massifs in Europe. We conclude that an Armorican terrane was juxtaposed against Avalonia well before the closure of the Variscan oceans and the formation of Pangea. The giant Cornubian Tin-Tungsten Ore Province and associated batholith can be accounted for by the fertility of Armorican lower crust and mantle lithosphere. 1 School of Geography, Earth and Environmental Sciences, Plymouth University, Plymouth PL4 8AA, UK. 2 Department of Core Research Laboratories, Natural History Museum, Cromwell Road, London, SW7 5BD UK. Correspondence and requests for materials should be addressed to A.H.D. (email: [email protected]) NATURE COMMUNICATIONS | (2018) 9:3770 | DOI: 10.1038/s41467-018-06253-7 | www.nature.com/naturecommunications 1 ARTICLE NATURE COMMUNICATIONS | DOI: 10.1038/s41467-018-06253-7 ilson’s cycle1 of the opening and closing of ocean typically form 10 cm to m-wide dykes and other types of minor Wbasins throughout Earth history was based on the intrusions cutting across Variscan foliations in Carboniferous and similarity of Early Palaeozoic faunal assemblages in Devonian rocks.
    [Show full text]
  • Phylogenetic and Phylogeographic Analysis of Iberian Lynx Populations
    Journal of Heredity 2004:95(1):19–28 ª 2004 The American Genetic Association DOI: 10.1093/jhered/esh006 Phylogenetic and Phylogeographic Analysis of Iberian Lynx Populations W. E. JOHNSON,J.A.GODOY,F.PALOMARES,M.DELIBES,M.FERNANDES,E.REVILLA, AND S. J. O’BRIEN From the Laboratory of Genomic Diversity, National Cancer Institute-FCRDC, Frederick, MD 21702-1201 (Johnson and O’Brien), Department of Applied Biology, Estacio´ n Biolo´ gica de Don˜ana, CSIC, Avda. Marı´a Luisa s/n, 41013, Sevilla, Spain (Godoy, Palomares, Delibes, and Revilla), and Instituto da Conservac¸a˜o da Natureza, Rua Filipe Folque, 46, 28, 1050-114 Lisboa, Portugal (Fernandes). E. Revilla is currently at the Department of Ecological Modeling, UFZ-Center for Environmental Research, PF 2, D-04301 Leipzig, Germany. The research was supported by DGICYT and DGES (projects PB90-1018, PB94-0480, and PB97-1163), Consejerı´a de Medio Ambiente de la Junta de Andalucı´a, Instituto Nacional para la Conservacion de la Naturaleza, and US-Spain Joint Commission for Scientific and Technological Cooperation. We thank A. E. Pires, A. Piriz, S. Cevario, V. David, M. Menotti-Raymond, E. Eizirik, J. Martenson, J. H. Kim, A. Garfinkel, J. Page, C. Ferris, and E. Carney for advice and support in the laboratory and J. Calzada, J. M. Fedriani, P. Ferreras, and J. C. Rivilla for assistance in the capture of lynx. Museo Nacional de Ciencias Naturales, Don˜ana Biological Station scientific collection, Don˜ana National Park, and Instituto da Conservac¸a˜o da Natureza of Portugal provided samples of museum specimens.
    [Show full text]