142 resultados para geolog??a


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Translation of Erdgeschichte.

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Vita.

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We present an improved database of planktonic foraminiferal census counts from the Southern Hemisphere Oceans (SHO) from 15°S to 64°S. The SHO database combines 3 existing databases. Using this SHO database, we investigated dissolution biases that might affect faunal census counts. We suggest a depth/[DCO3]2- threshold of ~3800 m/[DCO3]2- = ~-10 to -5 µmol/kg for the Pacific and Indian Oceans, and ~4000 m/[DCO3]2- = ~0 to 10 µmol/kg for the Atlantic Ocean, under which core-top assemblages can be affected by dissolution and are less reliable for paleo-sea surface temperature (SST) reconstructions. We removed all core-tops beyond these thresholds from the SHO database. This database has 598 core-tops and is able to reconstruct past SST variations from 2° to 25.5°C, with a root mean square error of 1.00°C, for annual temperatures. To inspect dissolution affects SST reconstruction quality, we tested the data base with two "leave-one-out" tests, with and without the deep core-tops. We used this database to reconstruct Summer SST (SSST) over the last 20 ka, using the Modern Analog Technique method, on the Southeast Pacific core MD07-3100. This was compared to the SSST reconstructed using the 3 databases used to compile the SHO database. Thus showing that the reconstruction using the SHO database is more reliable, as its dissimilarity values are the lowest. The most important aspect here is the importance of a bias-free, geographic-rich, database. We leave this dataset open-ended to future additions; the new core-tops must be carefully selected, with their chronological frameworks, and evidence of dissolution assessed.

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[ES] En las Canarias orientales, testimonios geológicos del inicio del Plioceno hasta la actualidad han permitido constatar la evolución paleoclimática desde una importante posición en el margen sahariano atlántico. Esta evolución revela la existencia de oscilaciones climáticas caracterizadas por la sucesión de climas que pasan de húmedos y cálidos a cálidos y áridos y que coinciden, respectivamente, con el inicio y el final de períodos interglaciales durante los que el mar fue transgresivo.

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Este documento presenta datos, informaci?n y an?lisis propios de un diagn?stico que se elabora para dise?ar un plan regulador cantonal de Alajuela, Costa Rica. Tambi?n presenta los retos inmediatos y estrat?gicos que enfrentan los pobladores de la isla individual y colectivamente. Incluye m?ltiples partes: un diagn?stico biof?sico que incluye mapas de uso del suelo. Una evaluaci?n de los recursos biol?gicos, amenazas naturales, la orograf?a y topograf?a, la geolog?a, capacidad de uso del suelo y sus potencialidades y vulnerabilidades. Tambi?n incluye un diagn?stico socio-econ?mico (poblaci?n, vivienda, empleo, actividad productiva y transporte) e historia de la ocupaci?n del cant?n. Esta parte se basa en la parte socioecon?mica.