(Table 1) Age determination of ODP Leg 134 volcanic rocks

The K-Ar ages from the basaltic rocks of Leg 134 range from Miocene to Holocene (Table 1). Samples were selected in consultation with shipboard scientists; choice of the material from the forearc sites was very limited and confined to clasts. There was a wider choice of material from the sill at Site 833 in the North Aoba Basin.

(Table 1) K and Ar content, and age determination of ODP Holes 126-792E and 126-793B

Results of conventional K-Ar dating on five samples from two sites from the Izu-Bonin forearc are presented. Two samples recovered from a volcanic edifice and overlying sediments drilled on the western side of the forearc basin (Site 792) indicate a basement age of 34 Ma. This is consistent with early Oligocene biostratigraphic ages from the overlying sediments. Three samples from the basement of Hole 793B at the center of the basin are not analytically distinguishable, with a best age of 27.1 +/- 0.6 Ma. This is slightly younger than the 30-33 Ma biostratigraphic and magnetostratigraphic estimates from the overlying sediments, suggesting that alteration processes have lowered the apparent K-Ar ages. These ages suggest that syn-rift volcanism occurred in a forearc location during the middle Oligocene.

Igneous geochemistry of OP Leg 126 samples

Major element, trace element, and radiogenic isotope compositions of samples collected from Ocean Drilling Program Leg 126 in the Izu-Bonin forearc basin are presented. Lavas from the center of the basin (Site 793) are high-MgO, low-Ti, two-pyroxene basaltic andesites, and represent the products of synrift volcanism in the forearc region. These synrift lavas share many of the geochemical and petrographic characteristics of boninites. In terms of their element abundances, ratios, and isotope systematics they are intermediate between low-Ti arc tholeiites from the active arc and boninites of the outer-arc high. These features suggest a systematic geochemical gradation between volcanics related to trench distance and a variably depleted source. A basement high drilled on the western flank of the basin (Site 792) comprises a series of plagioclase-rich two-pyroxene andesites with calc-alkaline affinities. These lavas are similar to calc-alkaline volcanics from Japan, but have lower contents of Ti, Zr, and low-field-strength elements (LFSE). Lavas from Site 793 show inter-element variations between Zr, Ti, Sr, Ni, and Cr that are consistent with those predicted during crystallization and melting processes. In comparison, concentrations of P, Y, LFSE, and the rare-earth elements (REE) are anomalous. These elements have been redistributed within the lava pile, concentrating particularly in sections of massive and pillowed flows. Relative movement of these two-element groupings can be related to the alteration of interstitial basaltic andesite glass to a clay mineral assemblage by a post-eruptive process. Fluid-rock interaction has produced similar effects in the basement lavas of Site 792. In this sequence, andesites and dacites have undergone a volume change related to silica mobility. As a result of this process, some lithologies have the major element characteristics of basaltic andesite and rhyolite, but can be related to andesitic or dacitic precursors by silica removal or addition.

Edipo saliendo de la caverna

El problema del conocimiento ha sido uno de los que mayor importancia ha tenido durante los siglos VI y IV a.C. en Grecia. Debido a esta importancia, dicho problema ha sido abordado desde diferentes perspectivas y ámbitos, como la poesía, la filosofía, la historia, etc. El objetivo del presente trabajo es hacer manifiestas las similitudes que existen entre el modo en que Sófocles concibe el conocimiento, y el modo en que lo concibe Platón. Para ello se analizaran pasajes del Edipo rey, de República y de Carta VII

La ironía en el Edipo Rey, (Prólogo y Episodio I). Hacia una redefinición y una propuesta tipológica de esta estrategia discursiva

En las últimas décadas los lingüistas dedicaron especial atención a la ironía, proponiendo diversas definiciones, mutuamente excluyentes que, quizás por prejuicios de escuela, priorizaban un solo aspecto de csta estrategia discursiva. Basándonos en la lectura de los primeros tramos del Edipo Rey, paradigmáticamente irónicos, intentaremos llegar a una definición comprensiva del recurso y propondremos una categorización de las ironías presentes en el texto, organizada sobre un doble eje enunciativo y retórico

La ironía en el Edipo Rey, (Prólogo y Episodio I). Hacia una redefinición y una propuesta tipológica de esta estrategia discursiva

En las últimas décadas los lingüistas dedicaron especial atención a la ironía, proponiendo diversas definiciones, mutuamente excluyentes que, quizás por prejuicios de escuela, priorizaban un solo aspecto de csta estrategia discursiva. Basándonos en la lectura de los primeros tramos del Edipo Rey, paradigmáticamente irónicos, intentaremos llegar a una definición comprensiva del recurso y propondremos una categorización de las ironías presentes en el texto, organizada sobre un doble eje enunciativo y retórico

Edipo saliendo de la caverna

El problema del conocimiento ha sido uno de los que mayor importancia ha tenido durante los siglos VI y IV a.C. en Grecia. Debido a esta importancia, dicho problema ha sido abordado desde diferentes perspectivas y ámbitos, como la poesía, la filosofía, la historia, etc. El objetivo del presente trabajo es hacer manifiestas las similitudes que existen entre el modo en que Sófocles concibe el conocimiento, y el modo en que lo concibe Platón. Para ello se analizaran pasajes del Edipo rey, de República y de Carta VII

Edipo saliendo de la caverna

El problema del conocimiento ha sido uno de los que mayor importancia ha tenido durante los siglos VI y IV a.C. en Grecia. Debido a esta importancia, dicho problema ha sido abordado desde diferentes perspectivas y ámbitos, como la poesía, la filosofía, la historia, etc. El objetivo del presente trabajo es hacer manifiestas las similitudes que existen entre el modo en que Sófocles concibe el conocimiento, y el modo en que lo concibe Platón. Para ello se analizaran pasajes del Edipo rey, de República y de Carta VII

Diatom biostratigraphy of sediments from the Kerguelen Plateau, Southern Ocean

The biostratigraphic distribution and abundance of lower Oligocene to Pleistocene diatoms is documented from Holes 747A, 747B, 748B, 749B, and 751A drilled during Ocean Drilling Program Leg 120 on the Kerguelen Plateau in the southeast Indian Ocean. The occurrence of middle and upper Eocene diatoms is also documented, but these are rare and occur in discrete intervals. The recovery of several Oligocene to Pleistocene sections with minimal coring gaps, relatively good magnetostratigraphic signatures, and mixed assemblages of both calcareous and siliceous microfossils makes the above four Leg 120 sites important biostratigraphic reference sections for the Southern Ocean and Antarctic continent. A high-resolution diatom zonation divides the last 36 m.y. into 45 zones and subzones. This zonation is built upon an existing biostratigraphic framework developed over the past 20 yr of Southern Ocean/Antarctic deep-sea coring and drilling. After the recent advances from diatom biostratigraphic studies on sediments from Legs 113, 114, 119, and 120, a zonal framework for the Southern Ocean is beginning to stabilize. The potential age resolution afforded by the high-diversity diatom assemblages in this region ranks among the highest of all fossil groups. In addition to the 46 datum levels that define the diatom zones and subzones, the approximate stratigraphic level, age, and magnetic anomaly correlative of more than 150 other diatom datums are determined or estimated. These total 73 datum levels for the Pliocene-Pleistocene, 67 for the Miocene, and 45 for the Oligocene. Greater stratigraphic resolution is possible as the less common and poorly documented species become better known. This high-resolution diatom stratigraphy, combined with good to moderately good magnetostratigraphic control, led to the recognition of more than 10 intervals where hiatuses dissect the Oligocene-Pleistocene section on the Kerguelen Plateau. We propose 12 new diatom taxa and 6 new combination

La ironía en el Edipo Rey, (Prólogo y Episodio I). Hacia una redefinición y una propuesta tipológica de esta estrategia discursiva

En las últimas décadas los lingüistas dedicaron especial atención a la ironía, proponiendo diversas definiciones, mutuamente excluyentes que, quizás por prejuicios de escuela, priorizaban un solo aspecto de csta estrategia discursiva. Basándonos en la lectura de los primeros tramos del Edipo Rey, paradigmáticamente irónicos, intentaremos llegar a una definición comprensiva del recurso y propondremos una categorización de las ironías presentes en el texto, organizada sobre un doble eje enunciativo y retórico

Age determination and stable isotope record of sediment cores at 9°S in the Indian Ocean

A continuous 10-m-long section consisting of roughly two thirds Ethmodiscus rex (a diatom) and one third mixed planktonic foraminifera was identified in a core from 3800 m depth at 9°S on the Indian Ocean's 90°E Ridge. Radiocarbon dates place the onset of deposition of this layer at >30,000 years B.P. and its termination at close to 11,000 years B.P. However, precise dating of the foraminifera from the Ethmodiscus layer itself proved to be impossible owing to the presence of secondary calcite presumably precipitated from the pore waters. During the Holocene, high calcium carbonate content ooze free of diatoms was deposited at this locale. As the site currently lies beneath the pathway taken by upper ocean waters entering the Indian Ocean from the Pacific (via the Indonesian Straits), it appears that during glacial time, thermocline waters moving along this same path provided the silica and other nutrients required by these diatoms.