997 resultados para Florescimento (maçã)


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Carlos Marzal (Valencia, 1961) es uno de los poetas españoles de mayor renombre en estas dos últimas décadas. El propósito de esta ponencia es acercarnos a su último poemario Ánima mía publicado en el año 2009. Como veremos en este trabajo la escritura poética de Marzal adhiere a una vasta genealogía que arranca en el siglo XVII, con la elección de un tono de voz próximo a la contención y la reducción que caracterizaran al barroco tanto hispánico como sajón. Más que de lecturas o influencias, Marzal prefiere hablar de la voluntad de 'unir ciertos nombres al suyo propio'. Así, desde la publicación de Metales pesados, libro bisagra en su trayectoria escritural, hay que mencionar los nombres de San Juan de la Cruz y Heráclito, Hiedegger y Tertuliano, Emily Dickinson y George Santayana, Manrique y Juan Ramón Jiménez, Bécquer y Miguel Hernández, José Hierro, John Keats y Horacio. Como veremos a lo largo de este trabajo, Anima mía es un libro de síntesis, de madurez y aprendizaje, de amoroso entendimiento con el mundo; un libro que se orienta hacia el tono celebratorio, el del canto de alabanza y la cadencia hímnica de visos claramente neorrománticos

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Fil: Udi, Juliana. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

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Fil: Udi, Juliana. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

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Carlos Marzal (Valencia, 1961) es uno de los poetas españoles de mayor renombre en estas dos últimas décadas. El propósito de esta ponencia es acercarnos a su último poemario Ánima mía publicado en el año 2009. Como veremos en este trabajo la escritura poética de Marzal adhiere a una vasta genealogía que arranca en el siglo XVII, con la elección de un tono de voz próximo a la contención y la reducción que caracterizaran al barroco tanto hispánico como sajón. Más que de lecturas o influencias, Marzal prefiere hablar de la voluntad de 'unir ciertos nombres al suyo propio'. Así, desde la publicación de Metales pesados, libro bisagra en su trayectoria escritural, hay que mencionar los nombres de San Juan de la Cruz y Heráclito, Hiedegger y Tertuliano, Emily Dickinson y George Santayana, Manrique y Juan Ramón Jiménez, Bécquer y Miguel Hernández, José Hierro, John Keats y Horacio. Como veremos a lo largo de este trabajo, Anima mía es un libro de síntesis, de madurez y aprendizaje, de amoroso entendimiento con el mundo; un libro que se orienta hacia el tono celebratorio, el del canto de alabanza y la cadencia hímnica de visos claramente neorrománticos

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Carlos Marzal (Valencia, 1961) es uno de los poetas españoles de mayor renombre en estas dos últimas décadas. El propósito de esta ponencia es acercarnos a su último poemario Ánima mía publicado en el año 2009. Como veremos en este trabajo la escritura poética de Marzal adhiere a una vasta genealogía que arranca en el siglo XVII, con la elección de un tono de voz próximo a la contención y la reducción que caracterizaran al barroco tanto hispánico como sajón. Más que de lecturas o influencias, Marzal prefiere hablar de la voluntad de 'unir ciertos nombres al suyo propio'. Así, desde la publicación de Metales pesados, libro bisagra en su trayectoria escritural, hay que mencionar los nombres de San Juan de la Cruz y Heráclito, Hiedegger y Tertuliano, Emily Dickinson y George Santayana, Manrique y Juan Ramón Jiménez, Bécquer y Miguel Hernández, José Hierro, John Keats y Horacio. Como veremos a lo largo de este trabajo, Anima mía es un libro de síntesis, de madurez y aprendizaje, de amoroso entendimiento con el mundo; un libro que se orienta hacia el tono celebratorio, el del canto de alabanza y la cadencia hímnica de visos claramente neorrománticos

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Fil: Udi, Juliana. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

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Calcareous nannoplankton assemblages and benthic d18O isotopes of Pliocene deep-sea sediments of ODP site 1172 (East of Tasmania) have been studied to improve our knowledge of the Southern Ocean paleoceanography. Our study site is located just north of the Subtropical Front (STF), an ideal setting to monitor migrations of the STF during our study period, between 3.45 and 2.45 Ma. The assemblage identified at ODP site 1172 has been interpreted as characteristic for the transitional zone water mass, located south of the STF, based on: (i) the low abundances (< 1%) of subtropical taxa, (ii) relatively high percentages of Coccolithus pelagicus, a subpolar type species, (iii) abundances from 2-10% of Calcidiscus leptoporus, a species that frequently inhabits the zone south of the STF and (iv) the high abundances of small Noelaerhabdaceae which at present dominates the zone south of the STF. Across our interval the calcareous nannoplankton manifests glacial-interglacial variability. We have identified cold events, characterized by high abundances of C. pelagicus which coincide with glacial periods, except during G7. After 3.1 Ma cold events are more frequent, in concordance with global cooling trends. Around 2.75 Ma, the interglacial stage G7 is characterized by anomalous low temperatures which most likely are linked to definite closure of the Central American Seaway (CAS), an event that is believed to have had global consequences. A gradual increase of very small Reticulofenestra across our section marks a significant trend in the small Noelaerhabdaceae species group and has been linked to a general enhanced mixing of the water column in agreement with previous studies. It is suggested that a rapid decline of small Gephyrocapsa after isotopic stage G7 might be related to the cooling observed in our study site after the closure of the CAS.

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We explore the applicability of paired Mg/Ca and 18O/16O measurements on benthic foraminifera from Southern Ocean site 747 to paleoceanographic reconstructions on pre-Pleistocene timescales. We focus on the late Oligocene through Pleistocene (27-0 Ma) history of paleotemperatures and the evolution of the d18O values of seawater (d18Osw) at a temporal resolution of ~100-200 kyr. Absolute paleotemperature estimates depend on assumptions of how Mg/Ca ratios of seawater have changed over the past 27 Myr, but relative changes that occur on geologically brief timescales are robust. Results indicate that at the Oligocene to Miocene boundary (23.8 Ma), temperatures lag the increase in global ice-volume deduced from benthic foraminiferal d18O values, but the smaller-scale Miocene glaciations are accompanied by ocean cooling of -1°C. During the mid-Miocene phase of Antarctic ice sheet growth (~15-13 Ma), water temperatures cool by ~3°C. Unlike the benthic foraminiferal d18O values, which remain relatively constant thereafter, temperatures vary (by 3°C) and reach maxima at ~12 and ~8.5 Ma. The onset of significant Northern Hemisphere glaciation during the late Pliocene is synchronous with an ~4°C cooling at site 747. A comparison of our d18Osw curve to the Haq et al. (1987, doi:10.1126/science.235.4793.1156 ) sea level curve yields excellent agreement between sequence boundaries and times of increasing seawater 18O/16O ratios. At ~12-11 Ma in particular, when benthic foraminiferal d18O values do not support a further increase in ice volume, the d18Osw curve comes to a maximum that corresponds to a major mid-Miocene sea level regression. The agreement between the character of our Mg/Ca-based d18Osw curve and sequence stratigraphy demonstrates that benthic foramaniferal Mg/Ca ratios can be used to trace the d18Osw on pre-Pleistocene timescales despite a number of uncertainties related to poorly constrained temperature calibrations and paleoseawater Mg/Ca ratios. The Mg/Ca record also highlights that deep ocean temperatures can vary independently and unexpectedly from ice volume changes, which can lead to misinterpretations of the d18O record.

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Pleistocene stable carbon isotope (d13C) records from surface and deep dwelling foraminifera in all major ocean basins show two distinct long-term carbon isotope fluctuations since 1.00 Ma. The first started around 1.00 Ma and was characterised by a 0.35 per mil decrease in d13C values until 0.90 Ma, followed by an increase of 0.60 per mil lasting until 0.50 Ma. The subsequent fluctuation started with a 0.40 per mil decrease between 0.50 and 0.25 Ma, followed by an increase of 0.30 per mil between 0.25 and 0.10 Ma. Here, we evaluate existing evidence and various hypotheses for these global Pleistocene d13C fluctuations and present an interpretation, where the fluctuations most likely resulted from concomitant changes in the burial fluxes of organic and inorganic carbon due to ventilation changes and/or changes in the production and export ratio. Our model indicates that to satisfy the long-term 'stability' of the Pleistocene lysocline, the ratio between the amounts of change in the organic and inorganic carbon burial fluxes would have to be close to a 1:1 ratio, as deviations from this ratio would lead to sizable variations in the depth of the lysocline. It is then apparent that the mid-Pleistocene climate transition, which, apart from the glacial cycles, represents the most fundamental change in the Pleistocene climate, was likely not associated with a fundamental change in atmospheric pCO2. While recognising that high frequency glacial/interglacial cycles are associated with relatively large (100 ppmv) changes in pCO2, our model scenario (with burial changes close to a 1:1 ratio) produces a maximum long-term variability of only 20 ppmv over the fluctuation between 1.00 and 0.50 Ma.

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The widely accepted age estimate for the onset of glaciation in the Northern Hemisphere ranges between 2 and 15 million years ago (Ma). However, recent studies indicate the date for glacial onset may be significantly older. We report the presence of ice-rafted debris (IRD) in ~44 to 30 Ma sediments from the Greenland Sea, evidence for glaciation in the North Atlantic during the Middle Eocene to Early Oligocene. Detailed sedimentological evidence indicates that glaciers extended to sea level in the region, allowing icebergs to be produced. IRD may have been sourced from tidewater glaciers, small ice caps, and/or a continental ice sheet.

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Various types of abrupt/millennial-scale climate variability such as Dansgaard/Oeschger and Heinrich Events characterized the last glacial period. Over the last decade, a number of studies demonstrated that such millennial-scale climate variability was not limited to the last glacial but inherent to Quaternary climate. Here we review the occurrence and origin of millennial ice-rafting events in the North Atlantic during the late Pliocene and Pleistocene (last 3.4 Ma) with a special focus on North Atlantic Hudson Strait (HS) Heinrich(-like) Events. Besides a clear biomarker signature, we show that Heinrich Layers 5, 4, 2, and 1 in marine sediment cores from across the North Atlantic all bear the organic geochemical fingerprint of the Hudson area. Using this framework and combining previously published results, detailed investigations into the organic and inorganic chemistry of ice-rafted debris (IRD) found across the North Atlantic demonstrate that prior to MIS 16 (~ 650 ka) IRD in the North Atlantic did not originate from the Hudson area of northern Canada. The signature of this early IRD is distinctly different compared to that of HS Heinrich Layers. Rather ice-rafting events during the late Pliocene and early Pleistocene predominantly emanated from the calving of the Greenland and Fennoscandian ice sheets and possibly minor contributions from local ice streams from the North American and British ice sheets. Compared to North Atlantic HS Heinrich Events, these early Pleistocene IRD-events had a limited impact on surface water characteristics in the North Atlantic. North Atlantic HS Heinrich(-like) Events first occurred during MIS 16. At the same time, the dominant frequency in silicate-rich IRD accumulation shifted from the obliquity (41-ka) to a 100-ka frequency across the North Atlantic. Iceberg survivability or a change in iceberg trajectory likely did not control this change in IRD-regime. These results lend further support for the existing hypothesis that an increase in size (thickness) of the Laurentide ice sheet controls the occurrence of North Atlantic HS Heinrich Events, favoring an internal dynamic mechanism for their occurrence.

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Clay mineral assemblages for the last 10 m.y. are described for Site 823, at 16°S in the Queensland Trough, to the northeast of Australia. Largely unaffected by diagenetic influences, these mostly express the evolution of northeastern Australian continental environments during the late Neogene: (1) beginning during the late Miocene at about 7.0 Ma is an increase of illite derived from rocky substrates at the expense of smectite from deeply weathered soils; this increase was the result of increasing aridity in the Australian interior and globally cooler temperatures, associated with increases in Antarctic glaciation; (2) concomitant and further increases of kaolinite fluxes to the Queensland Trough during the late Miocene-early Pliocene largely reflect an increase in rainfall in northeastern Australia; (3) increases in both soil- and rock-derived minerals probably intensified as a result of late Neogene uplift of the eastern highlands; (4) clay-mineral associations during the Pliocene and Pleistocene display minor variations only and probably resulted in part from differential settling and sea-level changes; (5) similar trends of clay-mineral variations occur at both ODP Site 823 and DSDP Site 588 (Lord Howe Rise). Less abundant kaolinite relative to illite at Site 588 nevertheless suggests a southward decrease of continental humidity and/or of the eastern highlands uplift; (6) influences of global climate and oceanic and atmospheric circulations on clay-mineral associations dominated during the late Miocene and were progressively replaced by influences of more regional environmental variations during the Pliocene and especially the Pleistocene.