995 resultados para 17-169
Resumo:
Evidence for the dissolution of biogenic silica at the base of pelagic sections supports the hypothesis that much of the chert formed in the Pacific derives from the dissolution and reprecipitation of this silica by hydrothermal waters. As ocean bottom waters flow into and through the crust, they become warmer. Initially they remain less saturated with respect to dissolved silica than pore water in the overlying sediments. With the diffusion of heat, dissolved ions, and to some extent the advection of water itself, biogenic silica in the basal part of the sedimentary section is dissolved. Upon conductively cooling, these pore waters precipitate chert layers. The most common thickness for the basal silica-free zone (20 m) lies below the most common height of the top of the chert interval above basement (50 m). This mode of chert formation explains the frequent occurrence of chert layers at very shallow subbottom depths in pelagic sections of the Pacific. It is also consistent with the common occurrence of cherts =150 m above basement.
Resumo:
Nineteen chert samples from a continuous core of the DSDP (Leg 17, Hole 167) were analysed for Ge; in addition we analysed five samples from other cores. The ages range between Late Jurassic, and Late Eocene. The concentration of Ge changes with age from 0.87 ppm in the oldest samples to 0.23 ppm in the youngest (equivalent to a Ge/Si decrease from 0.00000072 to 0.00000019). The decrease in Ge/Si is well correlated with the 87Sr/86Sr ratio in sea water of the relevant age. The interpretation of this trend may reflect: (a) different levels of Ge/Si in sea water as a result of a different ratio between hydrothermal and riverine input, (b) a diagenetic trend in siliceous sediments, (c) recording (by radiolaria) a transition between a radiolaria dominated ocean (with relatively high Ge/Si ratios in sea water) and diatom domination or (d) a combination of the above.
Resumo:
Oceanic basalts and other related igneous rocks are considered excellent recorders of the Earth's paleomagnetic field. Consequently, basalt core paleomagnetic data are valuable for the constraints they provide on plate tectonic motions, especially for oceanic plates such as the Pacific. Unfortunately, few Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) boreholes have been cored very deeply into the ocean crust. The result is that there are only a few sites at which a large enough number of basalt flows have been cored to properly average secular variation (e.g., Kono, 1980, doi:10.2973/dsdp.proc.55.135.1980; Cox and Gordon, 1984, doi:10.1029/RG022i001p00047). Furthermore, there are a number of sites where basaltic core samples were retrieved but the cores were not measured. Often this occurs because leg scientists had more important sections to work on, or the section was ignored because it was too short to record enough time to average secular variation and obtain a reliable paleolatitude. Even though it may not be possible to determine a precise paleolatitude from such short sections, measurements from a small number of flows are important because they can be combined with other coeval paleomagnetic data from the same plate to calculate a paleomagnetic pole (Gordon and Cox, 1980, doi:10.1111/j.1365-246X.1980.tb02642.x; Cox and Gordon, 1984, doi:10.1029/RG022i001p00047). For this reason, I obtained samples for paleomagnetic measurements from eight Pacific sites (169, 170, 171, 581, 597, 800, 803, and 865), most of which have not been previously measured for paleomagnetism.
Resumo:
Data from deep sea drilling, linear magnetic anomalies and bathymetric measurements together with age and morphometric characteristics of seamounts have been used to construct a paleobathymetric map of the oceans 35 million years ago. A brief analysis of these results is presented.
Resumo:
La reafirmación del modelo político-administrativo ciudadano tras la fase arcaica colonial abre una nueva etapa de prosperidad en la antigua fundación tiria. El esplendor de Gadir en el s. V a.C. se refleja en los textos clásicos y en los hallazgos arqueológicos y, sin embargo, nuestros conocimientos sobre el desarrollo histórico de la ciudad de época púnica son muy limitados. El horizonte arcaico comienza a esclarecerse tras los hallazgos del Teatro Cómico que han sacado a la luz los restos de la fundación tiria y, sin embargo, la ciudad posterior continúa siendo una gran incógnita. ¿A qué lugar se traslada la población una vez que se abandona el asentamiento primitivo? ¿Quiénes son los individuos enterrados en los excepcionales sarcófagos antropoides? ¿Qué relación jerárquica existe entre el asentamiento insular y los situados en tierra firme? ¿Qué papel jugó la industria y comercialización de las salazones? Los interrogantes planteados son múltiples y no hacen más que evidenciar la incapacidad del paradigma tradicional para explicar el desarrollo histórico de la Gadir postcolonial y la necesidad de buscar nuevos modelos interpretativos.
Resumo:
Trägerbände: Ms. Barth. 52; Ms. Barth. 66; Vorbesitzer: St. Peter Urach; Bartholomaeusstift Frankfurt am Main
Resumo:
Sono state valutate sperimentalmente le prestazioni di tre diversi collegamenti di Smart Metering in tre ambienti (urbano, sub-urbano e urbano denso) alla frequenza di 169 MHz. Grazie al calcolo del valore di Building Penetration Loss e dei valori di Path Loss è stato possibile stabilire le distanze massime di collegamento accentratore-meter al variare della probabilità di copertura.
Resumo:
Glaubt man dem päpstlichen Nuntius in der Schweiz, so war der Churer Bischof Johann VI. Flugi von Aspermont (1636–1661) alles andere als ein vorbildlicher Bischof: Er erbaue riesige Paläste, häufe für sich und seine Familie ein beträchtliches Vermögen an und betreibe Handel mit den für zukünftige Priester vorgesehenen Studienplätzen. Damit missachte er die Beschlüsse des Konzils von Trient (1545–1563), gemäss denen ein Bischof als geistlicher Oberhirte sein Handeln ausschliesslich in den Dienst der kirchlich-religiösen Erneuerung zu stellen habe. Der Beitrag argumentiert, dass die vom Nuntius kritisierten Praktiken mit einer tridentinischen Gesinnung nicht nur vereinbar waren, sondern paradoxerweise eine unabdingbare Voraussetzung für die katholische Reform im Bistum Chur darstellten. Um dies besser zu verstehen, werden diese Praktiken vor dem Hintergrund der sozialen Handlungslogiken frühneuzeitlicher Individuen beschrieben und beurteilt. Akteure wie der Churer Bischof verdankten ihre soziale Stellung einem einflussreichen Familienverband, dessen Sozial- und Ehrkapital es zu mehren galt. Soziales Prestige wiederum ermöglichte die Etablierung von Loyalitätsbeziehungen (Patron-Klient-Verhältnisse), über die sich letztlich Einfluss auf politische und kulturelle Entwicklungen nehmen liess. Fehlte, wie im Bistum Chur, die institutionelle und materielle Machtgrundlage für eine kompromisslose Durchsetzung von Reformen, so waren solche Mechanismen der gesellschaftlichen Verflechtung auch für kirchliche Akteure umso wertvoller.