Imaging the recent sediment dynamics of the Galicia Bank region (Atlantic,NW Iberian Peninsula)     

Gemma Ercilla  David Casas  Juan T. Vázquez  Jorge Iglesias  Luís Somoza  Carmen Juan  Teresa Medialdea  Ricardo León  Ferran Estrada  Soledad García-Gil  Marcel.lí Farran  Fernando Bohoyo  Margarita García  Adolfo Maestro  ERGAP Project  Cruise Teams 《Marine Geophysical Researches》2011,32(1-2):99

Multibeam bathymetry, high resolution multi-channel, and very high resolution single-channel (3.5 kHz) seismic records were used to depict the complex geomorphology that defines the Galicia Bank region (Atlantic, NW Iberian Peninsula). This region (≈620–5,000 m water depth) is characterized by a great variety of features: structural features (scarps, highs, valleys, fold bulges), fluid dynamics-related features (structural undulations and collapse craters), mass-movement features (gullies, channels, mass-flow deposits, slope-lobe complexes, and mass-transport deposits), bottom-current features (moats, furrows, abraded surface, sediment waves, and drifts), (hemi)pelagic features, mixed features (abraded surfaces associated to mixed sediments) and bioconstructions. These features represent architectural elements of four sedimentary systems: slope apron, contouritic, current-controlled (hemi)pelagic, and (hemi)pelagic. These systems are a reflection of different sedimentary processes: downslope (mass transport, mass flows, turbidity flows), alongslope (bottom currents of Mediterranean Outflow Water, Labrador Sea Water, North Atlantic Deep Water, and Lower Deep Water), vertical settling, and the interplay between them. The architectural and sediment dynamic complexities, for their part, are conditioned by the morphostructural complexity of the region, whose structures (exposed scarps and highs) favor multiple submarine sediment sources, affect the type and evolution of the mass-movement processes, and interact with different water masses. This region and similar sedimentary environments far from the continental sediment sources, as seamounts, are ideal zones for carrying out submarine source-to-sink studies, and can represent areas subject to hazards, both geologic and oceanographic in origin.  相似文献   

Tertiary compressional deformation of the Iberian plate     

A. M. Casas Sainz  & C. Faccenna 《地学学报》2001,13(4):281-288

The Tertiary deformation of the Iberian plate is here interpreted as the result of changes in the coupling between the Iberian–African plates. During the early stages of the Africa/Iberia subduction (Palaeocene), deformation was confined at the Betic plate boundary. From the Eocene, during the collision in the southern plate margin, compressional deformation delocalized and distributed throughout the Iberian plate. First, in the Pyrenees, where the main stage of thrusting occurred during the Late Eocene – Early Oligocene. Then (mainly Oligocene – Late Miocene), in the inner part of the Iberian plate, forming basement uplifts in the Iberian Chain and the Central System, in correspondence of pre-existing (Mesozoic and Variscan) structures. Finally, during the decay of compression inside the Iberian plate, extension took place the Mediterranean margin and the Alboran Sea.  相似文献   

Solar Rotation in the 17th century     

R. Casas  J. M. Vaquero  M. Vazquez 《Solar physics》2006,234(2):379-392

Sunspot drawings made by Galileo Galilei in 1612 are used to derive the law of differential rotation at that time. The main interest of the work is during the time of observations, just at the beginning of telescopic observations and some decades before the Maunder Minimum (1645 – 1715), a period where the sunspots almost disappeared from the solar surface. For this purpose we have carried out careful corrections of the different sources of errors derived from the observing technique. By comparing with other results of the same century, a significant difference is only detected by comparing with data corresponding to the deep Maunder Minimum (Paris Observatory drawings). The characteristics of the solar differential rotation, and extrapolating the behavior of solar activity, did not differ before or after the Maunder Minimum. We also include an analysis of hitherto ignored sunspot drawings by N. Bion made in October and November 1672.  相似文献   

The Spin Axis Position of C/1995 O1 (Hale–Bopp)     

Licandro  J.  Bellot Rubio  L. R.  Casas  R.  Gómez  A.  Kidger  M. R.  Sabalisk  N.  Santos-Sanz  P.  Serra-Ricart  M.  Torres-Chico  R.  Oscoz  A.  Jorda  L.  Denicolo  G. 《Earth, Moon, and Planets》1997,77(3):199-206

Monitoring of the near-nucleus activity of C/1995 O1 (Hale-Bopp) began in Teide Observatory in August 1995. During 1996 the comet was observed on 72 nights between March 26 and November 13. A permanent fan structure was observed towards the north during the whole period of observation. The position angle of the axis of this fan was measured and its variations with time were used to determine the position of the North Pole of the cometary nucleus. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Cadomian volcanosedimentary complexes across the Ediacaran–Cambrian transition of the Eastern Pyrenees,southwestern Europe     

Padel  Maxime  Álvaro  J. Javier  Casas  Josep Maria  Clausen  Sébastien  Poujol  Marc  Sánchez-García  Teresa 《International Journal of Earth Sciences》2018,107(5):1579-1601

International Journal of Earth Sciences - The volcanism hosted by the Ediacaran–Terreneuvian Canaveilles Group of the Eastern Pyrenees displays two distinct geochemical affinities: (1)...  相似文献   

New Archaeomagnetic Data from Tunisia: Dating of Two Kilns and New Archaeointensities from Three Ceramic Artifacts     

Lluís Casas  Boutheina Fouzai  Marta Prevosti  Nejia Laridhi‐Ouazaa  Ramon Jrrega  Siwar Baklouti 《Geoarchaeology》2016,31(6):564-576

Two isolated kilns of unknown age and three well‐dated artifacts from Tunisia have been investigated using archaeomagnetic techniques. Dating has been attempted for the kilns and archaeomagnetic intensities have been obtained for the artifacts. The kilns lack datable artifacts although one of them (Sidi Zahruni) could be related to a nearby late Roman site. Comparison with the SCHA.DIF.3K regional geomagnetic model suggests for both kilns two possible periods of last use, either Roman or Medieval. Three archaeomagnetic intensities were obtained for the well‐dated ceramic artifacts adding to scarce archaeomagnetic data from Africa. The new data along with recently published archaeointensities from other Tunisian sites have been compared with the regional model SCHA.DIF.3K, its updated version, and the global ARCH3k.1 geomagnetic model. The models show relatively good agreement with the new archaeointensities and with previously published intensities. The uncertainty of the experimental data tends to increase for older artifacts, and their agreement with the geomagnetic models diminishes. The observed trend of the intensity models to underestimate values in the Tunisian area for the Roman period could be overcome by adding new data from well‐dated artifacts from North African, particularly from pre‐Roman and Roman sites.  相似文献   

High precision symplectic integrators for the Solar System     

Ariadna Farrés  Jacques Laskar  Sergio Blanes  Fernando Casas  Joseba Makazaga  Ander Murua 《Celestial Mechanics and Dynamical Astronomy》2013,116(2):141-174

Using a Newtonian model of the Solar System with all 8 planets, we perform extensive tests on various symplectic integrators of high orders, searching for the best splitting scheme for long term studies in the Solar System. These comparisons are made in Jacobi and heliocentric coordinates and the implementation of the algorithms is fully detailed for practical use. We conclude that high order integrators should be privileged, with a preference for the new $(10,6,4)$ method of Blanes et al. (2013).  相似文献   

Comment on González-Acebrón et al. Criteria for the recognition of localization and timing of multiple events of hydrothermal alteration in sandstones illustrated by petrographic, fluid inclusion, and isotopic analysis of the Tera Group, Northern Spain Int J Earth Sciences (2011) 100:1811–1826     

Antonio M. Casas  Pedro del Río  Pilar Mata  Juanjo Villalaín  Luis Barbero 《International Journal of Earth Sciences》2012,101(7):2043-2048

  相似文献   

Physical and Geotechnical Properties and Assessment of Sediment Stability on the Continental Slope and Basin of the Bransfield Basin (Antarctica Peninsula)     

D. Casas  G. Ercilla  F. Estrada  B. Alonso  J. Baraza  H. Lee 《Marine Georesources & Geotechnology》2013,31(4):253-278

Our investigation is centred on the continental slope of the Antarctic Peninsula and adjacent basin. Type of sediments, sedimentary stratigraphy, and physical and geotechnical characterization of the sediments have been integrated. Four different types of sediments have been defined: diamictons, silty and muddy turbidites, muddy, silty and muddy matrix embedded clast contourites. There is a close correspondence between the physical properties (density, magnetic susceptibility and p-wave velocity) and the texture and/or fabric as laminations and stratification. From a quantitative point of view, only a few statistical correlations between textural and physical properties have been found. Within the geotechnical properties, only water content is most influenced by texture. This slope, with a maximum gradient observed (20°), is stable, according to the stability under gravitational loading concepts, and the maximum stable slope that would range from 22° to 29°. Nevertheless, different instability features have been observed. Volcanic activity, bottom currents, glacial loading-unloading or earthquakes can be considered as potential mechanisms to induce instability in this area.  相似文献   

Physical Properties and their Relationship to Texture and Consolidation Effects in Pliocene-Quaternary Sediments from Madeira Abyssal Plain     

D. Casas  G. Ercilla  J. Baraza  B. Coakley 《Marine Georesources & Geotechnology》2013,31(4):265-286

Multi-sensor core logger data and index properties were measured onboard the JOIDES resolution during ODP Leg 157 and compared with grain size distribution and carbonate contents measured in the on-shore laboratory. Cored sediments are similar in grain size, but very variable in carbonate content. Magnetic susceptibility clearly defines the volcanic turbidite layers, whereas GRAPE density and acoustic velocity help to define the coarser (silty) bases of some organic or calcareous turbidite layers. Index properties are mostly controlled by consolidation effects.  相似文献