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RAÚL DE LA HORRA Ma ISABEL BENITO JOSE LÓPEZ‐GÓMEZ ALFREDO ARCHE JOSÉ F. BARRENECHEA JAVIER LUQUE 《Sedimentology》2008,55(6):1849-1873
The Late Permian (Wuchiapingian) Alcotas Formation in the SE Iberian Ranges consists of one red alluvial succession where abundant soil profiles developed. Detailed petrographical and sedimentological studies in seven sections of the Alcotas Formation allow six different types of palaeosols, with distinctive characteristics and different palaeogeographical distribution, to be distinguished throughout the South‐eastern Iberian Basin. These characteristics are, in turn, related to topographic, climatic and tectonic controls. The vertical distribution of the palaeosols is used to differentiate the formation in three parts from bottom to top showing both drastic and gradual vertical upwards palaeoenvironmental changes in the sections. Reconstruction of palaeoenvironmental conditions based on palaeosols provides evidence for understanding the events that occurred during the Late Permian, some few millions of years before the well‐known Permian‐Triassic global crisis. 相似文献
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Potential seasonal calibration for palaeoenvironmental reconstruction using skeletal microstructures and strontium measurements from the cold‐water coral Lophelia pertusa 
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Chian Abraham C.-L. Abalde JOSÉ R. Alves M. Virginia Lopes Sergio R. 《Solar physics》1997,173(1):199-202
It is shown that narrow-band radio bursts of right- and left-hand circular polarizations from the Sun and flare stars can be produced via nonlinear conversion of Langmuir waves into high-frequency electromagnetic electron cyclotron waves near the plasma frequency by coupling to low-frequency electromagnetic cyclotron waves such as Alfvén-ion cyclotron or magnetosonic-whistler waves. 相似文献
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JOSÉ ANTONIO CONSTANTINE THOMAS DUNNE HERVÉ PIÉGAY G. MATHIAS KONDOLF 《Sedimentology》2010,57(2):389-407
Differences in the nature and quantity of sediment filling oxbow lakes have significant implications for the evolution of meandering rivers and the development of floodplains, influencing rates of meander migration and the valley width over which migration takes place. In an effort to identify the controls on the alluviation of oxbow lakes by coarse bed material, this study examined the sedimentary records stored within oxbow lakes of the Sacramento River of California, USA, and found that the volume of gravel in storage correlated negatively with the diversion angle separating flow between the river channel and the entrance into each lake. A method was devised for estimating the original channel bathymetry of the studied lakes and for modelling the hydraulic and sediment‐transport effects of the diversion angle within channels recently abandoned by meander cut‐off. The diversion angle determines the width of a flow separation within the abandoned‐channel entrance, reducing the discharge diverted from the river channel and thus limiting the ability of the abandoned channel to transport bed material. Aggradation rates are faster within entrances to abandoned channels with high diversion angles, resulting in the rapid isolation of lakes that store only a small volume of coarse‐grained sediment. Aggradation rates are slower within channel entrances where diversion angles are low, resulting in the slow transitioning of such channels into oxbow lakes with a larger and more extensive accumulation of coarse‐grained sediment. These findings compare well with observations in other natural settings and the mechanism which is described for the control of the diversion may explain why some oxbow lakes remain as open‐water environments for centuries, whereas others are filled completely within decades of cut‐off. 相似文献
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JOSÉ BETHENCOURT‐GONZÁLEZ PEDRO DORTA‐ANTEQUERA 《Geografiska Annaler: Series A, Physical Geography》2010,92(3):329-337
This work analyses a storm that occurred in the Canary Islands early in November 1826. Through a study based on historical climate data, some of the adverse effects of the storm are described and some of the possible causes are discussed. The main goal of this work is to establish an approximate reconstruction of this historical event which will allow us to compare it to a recent meteorological event that had a great impact on the archipelago: “Tropical Storm Delta”, in November 2005. Studying and reviewing the origin of the 1826 storm verifies the hypothesis that extremely violent perturbations have not only occurred in the Canaries on other occasions, but that these past events were also more intense and had more serious consequences than Delta. Therefore, the idea that other tropical perturbations have occurred in the region of the Canary Islands before Delta is presented. 相似文献
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Chronological and palaeoenvironmental context of human occupations at the Buendía rockshelter (Central Spain) during the late Upper Pleistocene in inland Iberia 下载免费PDF全文
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