992 resultados para 128-798C


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Downhole temperature and thermal conductivity measurements in core samples recovered during Legs 127 and 128 in the Japan Sea resulted in five accurate determinations of heat flow through the seafloor and accurate estimates of temperature vs. depth over the drilled sections. The heat flows measured at these sites are in excellent agreement with nearby seafloor measurements. Drilling sampled basaltic rocks that form the acoustic basement in the Yamato and Japan basins and provided biostratigraphic and isotopic estimates of the age of these basins. The preliminary age estimates are compared with predicted heat flow values for two different thermal models of the lithosphere. A heat flow determination from the crest of the Okushiri Ridge yielded an anomalously high heat flow of 156 mW/m**2. This excessive heat flow value may have resulted from frictional heating on an active reverse fault that bounds the eastern side of the Ridge. Accurate estimates of sedimentation rates and temperatures in the sedimentary section combined with models of basin formation provide an opportunity to test thermochemical models of silica diagenesis. The current location of the opal-A/opal CT transition in the sedimentary section is determined primarily by the thermal history of the layer in which the transition is now found. Comparison of the ages and temperatures of the layer where the opal-A/opal-CT is found today is compatible with an activation energy of 14 to 17 kcal/mole.

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Reseña sobre el libro Investigar con estudio de caso la dirección escolar escrito por Rosa Vázquez Recio, doctora y profesora titular de Didáctica y Organización escolar de la Universidad de Cádiz, sobre la realización de un estudio de caso acerca de la dirección escolar. La autora comparte sus temores y progresos, los dilemas y aciertos durante la realización de este estudio de caso a pie de escuela. Conocer su experiencia a través de este libro puede ayudar a quienes se inician en la tarea de la realización de estudios de caso o investigación sobre la dirección escolar así como a investigadores e investigadoras en general.

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Fil: Mallol, Anahí Diana. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

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57Fe Mössbauer spectra for 26 sediment and 6 carbonate concretion samples from Sites 798 and 799 were recorded at 293 K. Most spectra were deconvolved to two quadrupole doublets without magnetic hyperfine structure. Typical Mössbauer parameters were: isomer shift (I.S.) = 0.34 mm/s and quadrupole splitting (Q.S.) = 0.64 mm/s for the paramagnetic Fe3+ component (partly, pyrite); I.S. = 1.13 mm/s and Q.S. = 2.64 mm/s for the high-spin Fe2+ component derived from iron-bearing aluminosilicates. A few spectra included other high-spin Fe2+ components ascribed to iron-bearing carbonate minerals (e.g., ferroan magnesite), according to the Mössbauer parameters for Fe2+ in the carbonate concretions. We present the distribution of iron among different chemical forms as a function of depth. These data might indicate changes of depositional and diagenetic conditions.

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Fil: Mallol, Anahí Diana. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

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Reseña sobre el libro Investigar con estudio de caso la dirección escolar escrito por Rosa Vázquez Recio, doctora y profesora titular de Didáctica y Organización escolar de la Universidad de Cádiz, sobre la realización de un estudio de caso acerca de la dirección escolar. La autora comparte sus temores y progresos, los dilemas y aciertos durante la realización de este estudio de caso a pie de escuela. Conocer su experiencia a través de este libro puede ayudar a quienes se inician en la tarea de la realización de estudios de caso o investigación sobre la dirección escolar así como a investigadores e investigadoras en general.

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Reseña sobre el libro Investigar con estudio de caso la dirección escolar escrito por Rosa Vázquez Recio, doctora y profesora titular de Didáctica y Organización escolar de la Universidad de Cádiz, sobre la realización de un estudio de caso acerca de la dirección escolar. La autora comparte sus temores y progresos, los dilemas y aciertos durante la realización de este estudio de caso a pie de escuela. Conocer su experiencia a través de este libro puede ayudar a quienes se inician en la tarea de la realización de estudios de caso o investigación sobre la dirección escolar así como a investigadores e investigadoras en general.

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Nineteen trace elements, including seven rare earth elements (REE's), and 10 major and minor elements in 76 sediment samples from Sites 798 (Oki Ridge) and 799 (Yamato Trough) were determined by means of instrumental neutron activation analysis and X-ray fluorescence spectrometry. Most REE patterns (chondrite-normalized) of the sediments from both sites were nearly identical to the patterns of terrigenous materials. The cerium anomaly (slightly positive) frequently appeared in REE patterns of the sediments (200-750 mbsf) from Site 799. Cerium may be selectively incorporated into the sediments with hydrogenous manganese precipitation. However, the degree of the anomaly was not well correlated with manganese content, suggesting that cerium may behave as a trivalent REE (like the other REE's) during diagenesis while manganese is transported in the sediment column accompanied by reduction to a lower oxidation state. The Th/Sc ratio of the sediments from Sites 798 and 799 tended to decrease with penetration depth. Such a depth profile may indicate a decrease in basic volcanism activities from the Pliocene (Site 798) and Miocene (Site 799). The La/Yb ratio and degree of europium anomaly also varied with depth, which may imply that two or more components with different REE patterns were supplied throughout sedimentation at sites in the Japan Sea.