Lower to middle Miocene calcareous nannofossil events from the Ontong Java Plateau

Uppermost Oligocene through middle Miocene calcareous nannofossil events that were considered potentially useful from a biostratigraphic point of view have been investigated from Ocean Drilling Program Sites 806 and 807 in the western equatorial Pacific Ocean. Comparisons have been made to the corresponding events from other equatorial regions and the mid-latitude North Atlantic. In terms of biostratigraphic reliability, defined by the ability of the pertinent species to provide distinctive marker events and synchroneity over geographic distance, the investigated events can be classified into four general categories: The good markers: last occurrence (LO) Sphenolithus ciperoensis, first occurrence (FO) S. delphix, LO S. delphix, FO S. belemnos, LO S. belemnos, FO S. heteromorphus, termination acme (TA) Discoaster deflandrei, and LO Sphenolithus heteromorphus. The poor markers: LO Helicosphaera recta, TA Cyclicargolithus abisectus, LO Triquetrorhabdulus carinatus, and FO Calcidiscus macintyrei. Ecologically controlled markers with regional value: LO Dictyococcites bisectus, LO Helicosphaera ampliaperta, FO Reticulofenestra pseudoumbilica, LO Cyclicargolithus floridanus, and LO Coronocyclus nitescens. The low abundance markers: FO Discoaster druggii, gradational form of Sphenoliths dissimilis/Sphenolithus belemnos, FO Triquetrorhabdulus rugosus, and FO T. rioensis.

Condicionantes internos de la política exterior argentina : La participación del cuerpo decisional legislativo en el diseño de la agenda internacional de la política exterior argentina [1999-2003]

Fil: Sanchez, Leandro Enrique. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

Carbonate and bulk grain-size record for ODP Leg 130 holes

A major goal of Ocean Drilling Program (ODP) Leg 130 was to drill four sites down the northeastern flank of the Ontong Java Plateau to collect a series of continuous sedimentary sequences that would provide a depth transect of Neogene sediments. In particular, the study of the sediments recovered along the depth transect is expected to yield high-resolution stratigraphic, geochemical, and physical properties records across intervals of major paleoceanographic changes by evaluating variations of primary sedimentological and paleoceanographic indicators (e.g., carbonates, isotopes, grain size, microfossil assemblages, etc.). This data report presents the results of highresolution (3-5 Ka sample intervals) analyses of carbonate concentration and bulk sediment grain size at Sites 803-806 for the time interval from 2 Ma to the present.

La querella de la lengua en Argentina (1828-1928)

La tesis pretende demostrar que la formación identitaria de la Argentina se ha erigido, en buena medida, a partir de la querella en torno a la lengua que hablamos los argentinos. Esta querella consta de dos períodos. El primero se inicia en 1828, con el ensayo de Juan Cruz Varela sobre «Literatura Nacional», y tiene sus motivos más característicos durante el siglo XIX. El segundo viene de la mano del siglo XX, con Idioma nacional de los argentinos (1900), de Lucien Abeille, y sus estelas llegan hasta el día de hoy. Abeille puede considerarse una bisagra entre la vieja forma de estudiar las lenguas -ligada a la herencia del romanticismo y a la ciencia decimonónica-, y la nueva forma, de carácter ya lingüístico, que en España se desarrollaba en los albores del siglo XX. Estos dos períodos, no obstante, tuvieron como horizonte común discutir -ya sea negándolo, ya sea defendiéndolo- el idioma nacional, el idioma patrio, la lengua argentina, modos alternativos con que se ha aludido siempre a un mismo problema: la cuestión de la lengua en Argentina

Bulk calcite minor element composition of ODP Leg 130 samples

We investigated minor element ratios (Sr/Ca and Mg/Ca) in bulk sediment samples from Sites 803-807 using a recently optimized sample treatment protocol for calcium-carbonate-rich sediments consisting of sequential reductive and ion exchange treatments. We evaluated this protocol relative to bulk sediment leaching using samples from Sites 804 and 806, the two end-member sites in the depth transect, reporting as well Mn/Ca and Fe/Ca ratios for sediments from these two sites processed by means of both methods. The Sr/Ca ratios were only slightly affected by the sample treatment, with an average reduction of 6%-7% caused primarily by the ion exchange step. The reductive sample treatment, designed to be effective at removing Mn-rich oxyhydroxides, has a major effect on Mg/Ca ratios, with up to 50% reduction, whereas little effect occurred in ion exchange alone on Mg/Ca ratios. The Mn/Ca and Fe/Ca ratios were not consistently offset by the sample treatment, and these ratios do not appear to be representative of calcite geochemistry reflecting either ocean history or diagenetic overprinting. Celestite solubility appears to be an important control on interstitial water Sr concentrations in these sites, and it must be considered when constructing Sr mass balance models of calcite recrystallization. Calcite Sr/Ca ratios (range 1-2 mmol/mol) are similar from site to site when plotted vs. age, with a pattern comparable to that for well-preserved foraminifer tests over the past 40 Ma. Interstitial water Mg and Ca gradients appear to reflect basement character and the intensity of alteration; they can vary substantially over a small area. Calcite Mg/Ca ratios (range 1.5-4.5 mmol/mol) differ from site to site, with generally higher ratios for sites at a shallower water depth. Increasing calcite Mg/Ca ratios correlate with decreasing Sr/Ca ratios in the treated samples. No consistent pattern exists for calcite Mg/Ca ratios vs. age or depth, nor is any direct correlation to interstitial water Mg/Ca ratios present.

Age-depth correlations for Ontong Java Plateau sites

We used well logs, in some cases combined with shipboard physical properties measurements to make more complete profiles and to correlate between sites on the Ontong Java Plateau. By comparing sediment bulk density, velocity, and resistivity logs from adjacent holes at the same site, we showed that even subtle features of the well logs are reproducible and are caused by variations in sedimentation. With only minor amounts of biostratigraphic information, we could readily correlate these sedimentary features across the entire top of the Ontong Java Plateau, demonstrating that for most of the Neogene the top of the plateau is a single sedimentary province. We found it more difficult, but still possible, to correlate in detail sites from the top of the plateau to those drilled on the flanks. The pattern of sedimentation rate variation down the flank of the plateau cannot be interpreted as simply controlled by dissolution. Site 805, in particular, oscillates between accumulating sediment at roughly the same rate as cores on top of the Ontong Java Plateau, and accumulating sediment as slowly as Site 803, 200 m deeper in the water column. These oscillations do not match earlier reconstructions of central Pacific carbonate compensation depth variations.

La reserva natural Punta Lara : Área núcleo de la reserva de la biosfera Pereyra Iraola. Bases para una representación integrada en el espacio costero del Río de la Plata

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

Condicionantes internos de la política exterior argentina : La participación del cuerpo decisional legislativo en el diseño de la agenda internacional de la política exterior argentina [1999-2003]

Fil: Sanchez, Leandro Enrique. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

La reserva natural Punta Lara : Área núcleo de la reserva de la biosfera Pereyra Iraola. Bases para una representación integrada en el espacio costero del Río de la Plata

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

La querella de la lengua en Argentina (1828-1928)

La tesis pretende demostrar que la formación identitaria de la Argentina se ha erigido, en buena medida, a partir de la querella en torno a la lengua que hablamos los argentinos. Esta querella consta de dos períodos. El primero se inicia en 1828, con el ensayo de Juan Cruz Varela sobre «Literatura Nacional», y tiene sus motivos más característicos durante el siglo XIX. El segundo viene de la mano del siglo XX, con Idioma nacional de los argentinos (1900), de Lucien Abeille, y sus estelas llegan hasta el día de hoy. Abeille puede considerarse una bisagra entre la vieja forma de estudiar las lenguas -ligada a la herencia del romanticismo y a la ciencia decimonónica-, y la nueva forma, de carácter ya lingüístico, que en España se desarrollaba en los albores del siglo XX. Estos dos períodos, no obstante, tuvieron como horizonte común discutir -ya sea negándolo, ya sea defendiéndolo- el idioma nacional, el idioma patrio, la lengua argentina, modos alternativos con que se ha aludido siempre a un mismo problema: la cuestión de la lengua en Argentina