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1.
D. Parcerisa D. Gmez-Gras A. Trav J.D. Martín-Martín E. Maestro 《Journal of Geochemical Exploration》2006,89(1-3):318
Fe and Mn occur in calcite cements depending on the oxidizing–reducing conditions of cementing waters, which may change according to depositional and diagenetic environments. In red beds, Mn and Fe are available from the ferruginous matrix. Thus, it is possible to know the oxidizing–reducing conditions of fluids that precipitated calcite as a function of Mn and Fe content in calcite cement. A detailed petrological (with special attention to cathodoluminescence) and geochemical analysis of these cements is a useful tool to constrain the diagenetic evolution of red beds and the history of the basin where they deposited. 相似文献
2.
Palaeostresses inferred from brittle mesostructures in the eastern Duero Basin show a recent stress field characterized by an extensional regime, with local strike-slip and compressional stress states. Orientations of the maximum horizontal stress ( SHmax ) show a relative scattering with two main modes: NNE to NE–SW and NW–SE. These orientations suggest the existence of two stress sources responsible for the dominant directions of the maximum horizontal stress in northeastern Iberia. Extensional structures within a broad-scale compressional stress field can be related to both the decrease in relative stress magnitudes from active margins to intraplate regions and rifting proccesses ocurring in eastern Iberia. Stress states with NW–SE-trending SHmax are compatible with the dominant pattern established for western Europe. NE–SW orientations of SHmax suggest the occurrence of tectonic forces coming from the Pyrenean zone. Geological and geophysical data indicate the existence of both orientations from the upper Miocene to the present-day in NE Iberia. 相似文献
3.
Eudald Maestro 《Journal of Paleolimnology》2008,40(4):1053-1078
A complete third-order tectono-sedimentary cycle filled the Vernet lacustrine piggyback basin during the late Eocene. The
depositional sequence can be subdivided into five units or systems tracts with distinct architectural frameworks, which developed
a progressive unconformity. Sedimentary infilling of the piggyback basin began with retrogradational alluvial fans and fluvio-alluvial
deposits being deposited, arranged in two thinning- and fining-upward cycles during the uplifting and emplacement of the southernmost
Pyrenean thrusts, and with three thickening- and coarsening-upward progradational floodplain and lacustrine cycles, during
the quiescence of the southernmost thrusts, at the same time as the emplacement of several northernmost thrusts of the southern
Pyrenees. The facies associations identified represent different depositional environments in a sheetflow-dominated system,
including playa-lake deposits, floodplain deposits, sheetflow fluvial deposits and sheet deltas in ephemeral to shallow lacustrine
settings. Fourth and fifth order arid/semi-arid climatic cycles can be recognized, driven either by orbital obliquity and
precessional forcing (Milankovitch cyclicity), insolation cycles or possibly subprecessional autogenic mechanisms related
to the emplacement of northern thrusts and the consequent changes in the drainage basin. Arid periods are recorded by sheetflood
fluvial, ephemeral lacustrine or terminal splay deposits, with abundant medium-to-coarse-grained sandstone packages in red-to-grey
mudstones, a product of unconfined or low-confined sheetflows or hyperconcentrated flows, with bedload and suspended load,
during flood episodes, at times of lake lowstand. Semi-arid periods are recorded as relative highstand lacustrine deposits,
including grey-to-white mudstones deposited in prodelta environments and fine-grained sheet sandstone units sedimented in
a delta front (with minor channels and extensive sheet lobes) and prodelta environments in shallow lakes, from sheetflood
events. 相似文献
4.
G. Jané A. Maestro G. Ercilla J. López-Martínez J.R. De Andrés D. Casas D. González-Aller M. Catalán-Morollón 《Marine and Petroleum Geology》2010
A total of 445 pockmarks were observed on the upper continental slope of the northwest corner of the Iberian Peninsula (the Ortegal Spur area) by swath bathymetric and ultrahigh resolution seismic data. The pockmarks are U-, V- and W-shaped and have terraces or indentations in cross-section, and are dish-shaped (circular to oval) in plan view. They occur on the surface of the seabed and buried within the Plio-Quaternary and Neogene sediments. Four types of pockmarks were identified and mapped on the basis of their plan-view and cross-section morphology: regular, irregular, asymmetric and composite. The concentration of pockmarks is attributed to seepage of fluids migrating up-dip from deeper parts of the sedimentary basin. A linear high-density concentration with a NNW to N, NE and ESE trend of pockmarks is observed above inferred basement faults that do not affect the Quaternary succession. These pockmarks are thus caused by seepage of thermogenic gas and/or other pore fluids from deeper Late Cretaceous units, and their distribution may help to improve our understanding of the fluid system and migration regime in this part of the Galicia continental margin. 相似文献
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6.
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
7.
K. Batkov G. BigongiariP. Maestro P.S. MarrocchesiM.Y. Kim R. Zei 《Astroparticle Physics》2011,35(2):50-61
At an energy scale of 1015-1016 eV, a direct measurement of the energy carried by charged cosmic radiation is a real challenge for balloon-borne and space based instruments. As a consequence of the very small fluxes, a large collecting power is required which is difficult to accommodate with weight-limited instruments equipped with calorimeters. A different approach has been proposed that might allow for a sizeable reduction of the instrument mass. It is based on a kinematical technique, whereby the energy of the cosmic-ray is estimated on the basis of the measured angular distribution of the secondaries resulting from its interaction in a target. In this paper, we review the basic principles of the method and study the properties of different energy estimators by means of a full simulation of the interaction of the incident particle in a conceptual instrument. We also discuss the intrinsic limitations of the method and investigate its possible application to direct measurements of the cosmic-ray spectrum in the region of the ‘knee’. 相似文献
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9.
Antonio Pedrera Jesús Galindo‐Zaldívar Ana Ruiz‐Constán Fernando Bohoyo Pablo Torres‐Carbonell Patricia Ruano Adolfo Maestro Lourdes González‐Castillo 《地学学报》2014,26(6):448-453
Forests situated above active fault zones may record hillslope evolution, thus holding information about recent seismic events. Lenga trees (Nothofagus pumilio) extend across the Magallanes–Fagnano fault system (MFFS), the active transform boundary between the South American and Scotia plates. Coseismic surface ruptures along the fault scarp tilt trees located uphill. During the interseismic period, tree growth curves the trunks. Annual tree rings from the study area show abrupt changes from concentric to asymmetric, allowing the timing of major historical earthquakes to be established. In this case, tree‐ring analysis suggests rupture on the MFFS fault scarp in 1883 ± 5 and 1941 ± 10, coinciding with the February 1, 1879 (Modified Mercalli Scale, VI) and the December 17, 1949 (Ms 7.8) earthquakes in Tierra del Fuego. Our results provide evidence that this fault system was the source of these earthquakes, which has implications for seismic hazard in the study region. 相似文献
10.
P.S. Marrocchesi M.G. BagliesiK. Batkov G. BigongiariM.Y. Kim P. Maestro 《Astroparticle Physics》2011,35(1):21-27
Measurements of the relative abundance of cosmic isotopes and of the energy dependence of their fluxes may clarify our present understanding on the confinement time of charged cosmic rays in the Galaxy. Experimental studies of these propagation clocks have been carried out by balloon and space missions at energies of a few 100 MeV/amu by means of detection techniques based on multiple dE/dx sampling, coupled with a measurement of the energy released in a thick absorber. At larger energies, the isotopic separation of light nuclei (as, for instance,9Be/10Be) can be achieved by combining a precise measurement of the particle’s rigidity with an high resolution determination of its velocity, via the observation of the Cherenkov effect in a radiator.In this paper, we propose the introduction - for the first time in a space experiment - of the DIRC technique (Detection of Internal Reflected Cherenkov light) for the identification of cosmic-ray isotopes. This type of detector has been successfully used in electron-positron colliders for particle identification and in particular for π-K separation. While for particles with unit charge the light yield is a limiting factor, in the case of a nucleus of charge Z the larger photostatistics (due to the Z2 dependence of Cherenkov light emission) is the key to reach an adequate angular resolution to provide a mass discrimination for isotopes of astrophysical interest. We report on the early development phase of a DIRC prototype with a focussing scheme (FDIRC) to collect the Cherenkov light onto a detector plane instrumented with a Silicon PhotoMultiplier (SiPM) array. 相似文献