Structural styles of the Shuilikeng fault system in the central Taiwan mountain belt Estilos estructurales del sistema de fallas Shuilikeng en la parte central de la cordillera de Taiwan

Abstract: The Shuilikeng fault system in the central Taiwan mountain belt forms the structural boundary between two different tectonostratigraphic zones: the Western Foothills to the W, and the Hsuehshan Range to the E. It comprises a steeply-dipping roughly north-striking transpressive fault zone with splays, folds and bifurcations linked to the main structure. The structural style of the Shuilikeng fault system changes from N to S; while to the N it is defined by diverging splay and non-cylindrical folds branching off the Shuilikeng fault, to the S its structure is dominated by east-striking right-lateral strike-slip faults in the Hsuehshan Range and by a rejoining splay with a composite kinematics in the Western Foothills. At the southernmost tip of the study area, the Shuilikeng fault is defined by a several hundred meters-wide high strain zone and the structural architecture of the Western Foothills is that of a regional anticlinorium branching off the Shuilikeng fault intensely folded and faulted along its limbs. Key words: Taiwan, fault system, transpression. Resumen: El sistema de fallas Shuilikeng en la parte central de la cordillera de Taiwan forma el límite estructural entre dos zonas tectonoestratigráficas diferentes: las Wester

Seismic structure of the northern continental margin of Spain from ESCIN deep seismic profiles

By the end of the Carboniferous, the crust of the continental shelf in northwestern Spain was made up of deeply rooted structures related to the Variscan collision. From Permian to Triassic times the tectonic setting had changed to mainly extensional and the northern Iberian continental margin underwent rifting during Late Jurassic-Early Cretaceous times, along with sea-floor spreading and the opening of the Bay of Biscay until the Late Cretaceous. Subsequently, the northern Iberian margin was active during the north-south convergence of Eurasia and Iberia in the Tertiary. A multichannel seismic experiment, consisting of two profiles, one north-south (ESCIN-4) crossing the platform margin offshore Asturias, and another (ESCIN-3) crossing the platform margin to the northwest of Galicia, was designed to study the structure of the northern Iberian margin. The ESCIN-4 stacked section reveals inverted structures in the upper crust within the Le Danois Basin. North of the steep continental slope, ESCIN-4 shows a thick sedimentary package from 6 to 9.5 s, two-way travel time (TWT). Within this latter package, a 40-km-long, north-tapering wedge of inclined, mainly south-dipping reflections is thought to represent a buried, Alpine-age accretionary prism. In the north western part of the ESCIN-3 (ESCIN-3-1) stacked section, horizontal reflections from 6.5 to 8.5 s correspond to an undisturbed package of sediments lying above oceanic-type basement. In this part of the line, a few kilometres long, strong horizontal reflection at 11.2 s within the basement may represent an oceanic Moho reflection. Also, a band of reflections dips gently towards the southeast, from the base of the gently dipping continental slope. The part of ESCIN-3 line that runs parallel to the NW-Galicia coast (ESCIN-3-2), is characterized by bright, continuous lower crustal reflections from 8 to 10 s. Beneath the lower crustal reflectivity, a band of strong reflections dips gently toward the southwest from 10 to 13.5 s. The part of ESCIN-3 that parallels the northern margin (ESCIN 3-3), shows good reflectivity in all levels. Upper crustal reflections image the sedimentary fill of probable Mesozoic to recent basins. Mid-crustal reflectivity is characterized by dipping reflections until 8 s that are probably related to compressional Variscan features. The lower crustal level shows 'layered' reflections between 8 and 12 s. Dipping reflections are found below the continental Moho.J. Alvarez-Marrón held a post-doc research grant from the Ministry of Education and Science of Spain. The ESCI-N program was sponsored by the Spanish agencies CICYT (project GEO 90-0660) and FICYT, and STRIDE Program of the EU.Peer Reviewe

Four decades of geophysical research on Iberia and adjacent margins

The dimensions, the geographical position and the complex geological history of the Iberian Peninsula makes it a unique and singular target to study its crustal and upper mantle structure and geodynamical evolution using geophysical methods. The lithospheric structure beneath Iberia has been investigated since the 1970’s using deep multichannel seismic reflection and refraction/wide-angle reflection profiling. Gravimetric and magnetic data were acquired following the deployment of permanent and temporary stations, mostly during the 1990’s. Beginning in the late 1990’s, the progressive use of Global Navigation Satellite Systems (GNSS) instruments contributed to monitor the present-day motions. During the last decades, numerous geological and geophysical surveys have investigated the Iberian lithosphere and upper mantle in the onshore and offshore regions, the most recent ones related to the TopoIberia project. The approach developed in this contribution is twofold. Firstly, we summarize the available geophysical information over Iberia, from focusing on the upper crust to the lithosphere-asthenosphere boundary and the transition zone marking the bottom of the upper mantle. Results of GNSS data, potential fields, controlled source seismic profiles, magnetotelluric data, body and surface wave tomography, receiver functions and 2D and 3D lithospheric modeling are reviewed and compared. Secondly, we focus on the areas of greater geodynamic interest and the regions where inconsistencies within the geophysical results, or contradictions in their tectonic interpretation exist, identifying the major questions that are still under debate. Besides shedding light to the state of knowledge and pointing out present-day research challenges, this review provides a tool for the integration of the diverse geophysical datasets with the surface geology and geodynamical processes that are interpreted to have built the complex geology of the Iberian Peninsula.The authors acknowledge funding from the Generalitat de Catalunya, grant/awards number AGAUR 2017SGR1022, and AGAUR 2017SGR847, the Spanish Ministry of Science, Innovation, and Universities grant numbers RTI2018-095594-B-I00, PGC2018-095154-B-100 and PGC2018-094227-B-I00 and the Spanish Ministry of Economy and Competitiveness grant numbers CGL2017-84901-C2 and PIE-CSIC-201830E039. IP is funded by the Spanish Ministry of Science, Innovation, and Universities and University of Salamanca grant BEAGAL18/00090. AV acknowledges funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S).Peer reviewe

Factors associated with commencing smoking in 12-year-old students in Catalonia (Spain): a cross-sectional population-based study

<p>Abstract</p> <p>Background</p> <p>Over the last decade notable progress has been made in developed countries on monitoring smoking although experimenting with cigarettes and smoking in young people remains a serious public health problem. This paper reports a cross-sectional study at the beginning of the 3-year follow-up community study TA_BES. The aim was to study the prevalence of smoking in addition to determining predictive factors for when smoking commences in a representative population of 12-year-old first year compulsory secondary education students.</p> <p>Methods</p> <p>Twenty-nine secondary schools (N = 29) from an area of Catalonia participated in the study. In these schools 2245 students answered a questionnaire to study the attitudes, behaviors, and tobacco consumption in the subject's surrounding circle and family in relation to smoking; carbon monoxide measurements were taken by means of co-oximetry on 2 different occasions. A smoker was defined as a student who had smoked daily or occasionally in the last 30 days. For non-smokers the criteria of not considering was set up for those who answered that in the future they would not be smokers and considering those who answered that they did not rule out becoming a smoker in the future.</p> <p>Results</p> <p>Among the total 2245 students included in the analysis 157(7%) were classified as smokers. Among non-smokers we differentiated between those not considering smoking 1757 (78.3%) and those considering smoking 288 (12.8%).</p> <p>Age is among the factors related to commencing smoking. The risk of becoming a smoker increases 2.27 times/year. The influence of the group of friends with a very high risk for boys OR 149.5 and lower, albeit high, in girls OR 38.1. Tobacco consumption of parents produces different effects in young people. A smoking father does not produce alterations in the smoking behavior of young people. However having a smoking mother or former smoking is a risk factor for boys and a protective factor for girls.</p> <p>We detected a gradual risk of becoming a smoker by means of the co-oximetry test. A boy/girl with a test between 6 p.p.m and 10 p.p.m increased the probability of smoking by 2.29 and co-oximetry values > 10 p.p.m multiplied the risk 4 times over.</p> <p>Conclusions</p> <p>Results indicate that the age of commencing smoking is maintained in spite of prevalence having decreased in the last few years. The risk factors identified should be used to involve families and the educational community by offering them tobacco weaning programmes.</p

Origin, structure and exposure history of a wave-cut platform more than 1 Ma in age at the coast of northern Spain: A multiple cosmogenic nuclide approach

19 pages, 9 figures, 4 tables.-- Available online Mar 19, 2007.Along the Asturian coast of northern Spain an uplifted wave-cut platform extends for not, vert, similar 100 km east–west. The steep cliff which bounds the gently seaward-dipping platform to the north increases in height from 30 m in the west to 100 m in the east and reflects the overall eastward increase in platform elevation. The southern edge of the 2–4 km-wide platform runs along the foothills of the Cantabrian Mountains, as constrained by a high-resolution digital elevation model. The marine platform, which was carved into deformed Paleozoic bedrock with abundant quartzite beds, is largely covered by weathered marine and continental sediments. Quartzite samples from flat bedrock outcrops which are currently not covered by sediment or soil yield cosmogenic nuclide concentrations (21Ne, 10Be and 26Al) that demonstrate a long and complex exposure history, including periods of burial with partial or complete shielding from cosmic rays. The combination of multiple cosmogenic nuclides yields a minimum age of 1–2 Ma for the platform. Taking into account (i) the horizontal and vertical extent of the platform, (ii) the high resistance to erosion of the quartzitic bedrock, and (iii) published data on the magnitude of past sea level fluctuations, we suggest that the wave-cut platform formed in the Pliocene. Subvertical faults cutting the platform at high angles to the coastline offset the southern edge of the platform by 20 to 40 m and reactivate the pre-existing anisotropy in the Paleozoic bedrock. Uplift and crustal deformation of the coastal region have occurred after platform formation in the Pliocene and may still be active. The slow deformation of the northern edge of the Iberian plate including the Cantabrian Mountains may result from the ongoing slow convergence at an incipient subduction zone extending along the coast of northern Spain.This research was funded by the Spanish Ministry of Education and Science, through projects BTE2002-00330 from the National Research Plan and project CGL2005-24204, and by the GeoForschungsZentrum Potsdam.Peer reviewe

Seismic Study of the Iberian Crust, ESCI-North survey

Two onshore profiles were acquired in E-W and N-S directions through the Variscan and Alpine domains of 140 and 65 km length, ESCI-N1 and ESCI-N2 respectively. Also two offshore profiles ESCI-N3 and ESCI-N4 were obtained with a streamer of 4500 m having 360 channels with a 12.5 m gap between them and a 40 l airgun capacity. ESCI-N3 follows a swerved line in a mainly E-W direction crossing the Variscan structures. ESCI-N4 is a N-S direction profile that crosses both the Cantabrian margin and Le Danois bank Alpine structures. Techincal specifications of offshore profiles: streamer length 4,500 m, 360 channels, group interval 12,5 m and sample rate 4 ms.The ESCI-N project in Northwestern Spain was a subprogram of the ESCI Program (Estudios Sísmicos de la Corteza Ibérica). It is formed by four seismic experiments both on and offshore. This project aimed to image the Cantabrian Zone, West Asturian-Leonese Zone and the northern Iberian margin, thus characterizing the crustal structure resulted from the Variscan and Alpine orogenies and the Mesozoic extension related to the opening of the Bay of Biscay.CICYT (Committee of Science and Technology of the Spanish Ministry of Education and Science), GEO90-0660.-- FICYT (Fundación para el Fomento en Asturias de la Investigación Científica Aplicada y la Tecnología).-- Science and Technology for Regional Innovation and Development in Europe-European CommissionPeer reviewe

Preface: From orogenesis to geoscience in the service of society: the scientific legacy of Prof. Andrés Pérez-Estaún

No abstract

Is the Ibero-Armorican Arc primary or secondary? An analysis of the contraction required to form it by rotation around a vertical axis

Various models have been proposed to explain the formation of the Ibero-Armorican Arc (IAA) as either primary or secondary (rotational). Models for secondary arc formation require significant rotation around a vertical axis at the end of the Variscan orogeny. Estimates for the amount of north–south (present coordinates) contraction (horizontal shortening) required for these rotations range from 54 at the core to 91% at the SE tip of the arc, near to the present day Mediterranean coast. These estimates are compared with coeval deformational structures developed in three areas of the orogen: (1) in the autochthonous hinterland in the southern branch of the arc; (2) in the Cantabrian Zone foreland fold–thrust belt in the core of the arc; and (3) in the SE continuation of the southern branch of the IAA in the present day Iberian Chain. From this analysis it follows that the contraction associated with late Variscan deformation is much less than that needed to explain the formation of the IAA from a formerly linear orogen via rotation around a vertical axis. We therefore propose that the geometry of the arc should be re-evaluated. We discuss the palaeomagnetic data purported to support the secondary origin, as well as the role of late Variscan regional strike-slip faults in modifying the geometry of the Iberian and Armorican massifs. Our analysis suggests that the IAA formed mainly from a primary non-rotational margin-controlled curvature, slightly modified by c. 5–20% of superposed contraction during late Carboniferous and/or Alpine times.Financial support was provided by CGL2017-87631-P, CGL2016-76438-P, PGC2018-093903-B-C22 and SALTCONBELT-CGL2017-85532-Pprojects, funded by Agencia Estatal de Investigación (AEI) and Fondo Europeode Desarrollo Regional (FEDER), and by project 2014SGR-467 (UB-GEOMODELS Research Institute and the Grup de Geodinàmica i Anàlisi deConques). IDS is grateful for financial support given by the Estímulo ao EmpregoCientífico–Norma Transitória national science contract in the Faculdade deCiências da Universidade de LisboaPeer reviewe