Chemical composition of Lake George (New York) iron-manganese nodules and underlying sediment

Lake George, New York, is the site of a new discovery of iron-manganese nodules. These nodules occur at a water depth between 21 and 36 m along a stretch of lake extending for about 5 mi north and south of the Narrows, a constricted island-dotted area which separates the north and south Lake George basins. Nodules occur on or within the uppermost 5 cm of a varved glacial clay. Some areas are solidly floored with a carpet of nodules in areas where active currents keep the nodules exposed. The nodules form around nuclei which consist of clay and less commonly of spore capsules, detrital particles, or bark. By their shape we recognize three types of nodules: spherical, discoidal, and lumps. On X-ray examination all nodules show small goethite peaks; in one nodule the manganese mineral birnessite was identified. Manganese and part of the iron appears to be in X-ray amorphous ferromanganese compounds. The Lake George nodules are enriched in iron with respect to marine nodules but are lower in manganese. They have a higher trace element concentration than nodules from other known freshwater lake occurrences, but a lower concentration than marine nodules.

Dust flux records from the Subarctic North Pacific

We present a new record of eolian dust flux to the western Subarctic North Pacific (SNP) covering the past 27000 years based on a core from the Detroit Seamount. Comparing the SNP dust record to the NGRIP ice core record shows significant differences in the amplitude of dust changes to the two regions during the last deglaciation, while the timing of abrupt changes is synchronous. If dust deposition in the SNP faithfully records its mobilization in East Asian source regions, then the difference in the relative amplitude must reflect climate-related changes in atmospheric dust transport to Greenland. Based on the synchronicity in the timing of dust changes in the SNP and Greenland, we tie abrupt deglacial transitions in the 230Th-normalized 4He flux record to corresponding transitions in the well-dated NGRIP dust flux record to provide a new chronostratigraphic technique for marine sediments from the SNP. Results from this technique are complemented by radiocarbon dating, which allows us to independently constrain radiocarbon paleoreservoir ages. We find paleoreservoir ages of 745 ± 140 yr at 11653 yr BP, 680 ± 228 yr at 14630 yr BP and 790 ± 498 yr at 23290 yr BP. Our reconstructed paleoreservoir ages are consistent with modern surface water reservoir ages in the western SNP. Good temporal synchronicity between eolian dust records from the Subantarctic Atlantic and equatorial Pacific and the ice core record from Antarctica supports the reliability of the proposed dust tuning method to be used more widely in other global ocean regions.

La dimensión moral en el marxismo : la justicia distributiva en Marx y en los marxistas analíticos

El artículo aborda la dimensión moral en el marxismo desde el enunciado del concepto de justicia distributiva. La existencia explícita o implícita de una dimensión moral en el marxismo ha sido discutida en la bibliografía, sobre todo a partir del análisis de los propios textos de Marx. El artículo afirma la existencia de una noción transhistórica y absoluta de justicia en Marx y en el grupo de los marxistas analíticos, aunque en éstos últimos con distintas variantes.

Manganese concentrations and flux data of sediments from Broken and Ninetyeast Ridge

Decomposition of organic matter combined with density stratification generate a pronounced intermediate water oxygen minimum zone (OMZ) in the northwest Indian Ocean. This zone currently lies between water depths of 200 and 2000 m and extends approximately 5000 km southeast from the Arabian coast. Based upon benthic foraminiferal assemblage changes, it has been suggested that this OMZ was even more extensive during the late Miocene-early Pliocene (6.5-3.0 Ma), with a maximum volume and/or intensity at approximately 5.0 Ma. While this inference may contribute to an understanding of the history of northwest Indian Ocean upwelling, corroborating geochemical evidence for this interpretation has heretofore been lacking. Ocean Drilling Program (ODP) sites 752, 754, and 757 on Broken and Ninetyeast ridges are located within central Indian Ocean intermediate water depths (1086-1650 m) but outside the present lateral dimensions of the Indian Ocean OMZ. High-resolution chemical analyses of sediment from these sites indicate significant reductions in the flux of Mn and normalized Mn concentrations between 6.5 and 3.0 Ma that are most pronounced at approximately 5.0 Ma. Because late Miocene-Pliocene paleodepths for these sites were essentially the same as at present and because extremely low sedimentation rates (0.3-1.3 cm/ky) most likely precluded sedimentary metal oxide diagenesis, we suggest that the observed Mn depletions reflect diminished deposition of reducible Mn oxyhydroxide phases within O2 deficient intermediate waters and that this effect was most intense at approximately 5.0 Ma. This interpretation implies that waters with less than 2.0 mL/L O2 extended at least 1500 km beyond their present limits and is consistent with changes in benthic foraminifera assemblages. We further suggest this expanded Indian Ocean OMZ is related to regionally and/or globally increased biological productivity.

“Miram concordia et harmonia" : la relación naturaleza-persona en San Buenaventura

El presente trabajo muestra la analogía bonaventuriana en términos de distancia y espejo, señalando las instancias argumentativas a través de las cuales se llega al concepto de naturaleza entendido como expresión de Dios. Pero además, esta similitudo, a diferencia de la imagen, es cualidad pura común a todos los seres, y designa un modo eminente de participación en la perfección divina, que se imprime en un despliegue trinitario ad intra (Logos) a la vez que se expresa en la creación ad extra. Estos momentos metafísicos de impressio-expressio conforman la propia realidad divina y la posibilidad de acceso a ella por parte de la naturaleza participada. En la Distinción 25 de su Comentario a las Sentencias de Pedro Lombardo, Buenaventura hará uso de un concepto de analogía propio para explicar la relación entre Persona-divina y persona-creatura, en un ámbito ante todo metafísico que sobrepasa los aspectos preteológico y cosmológico. Por ello, además de permitirnos esclarecer la diferencia entre naturaleza y persona-creatura, la importancia de esta analogía planteada por Buenaventura radica en que proporciona una respuesta particular a la oposición naturaleza-Dios, en la que la diferencia no significa exclusión, sino, maravillosa concordia y harmonía".

Alberto Magno y Buenaventura sobre la eternidad del mundo : aproximaciones y divergencias

La tesis aristotélica acerca de la eternidad del mundo y su prolongación averroísta incide en el pensamiento escolástico con anterioridad al estallido del conflicto en la Universidad de París. Ambos maestros de teología, el dominico y el franciscano, toman partido por la tesis contraria; en el caso de Alberto Magno hay una inclinación hacia la imposibilidad de presentar desde la filosofía argumentos que sostengan su posición, como así también argumentos que avalen la posición contraria. La razón aducida por Alberto es que no se trata de un tema propio de la física, sino perteneciente al orden sobrenatural. Buenaventura en cambio propone una serie de argumentos que desarrolla a partir de los mismos términos empleados por Aristóteles para fundamentar su tesis, pero indicando las contradicciones que surgen de los mismos. El presente trabajo confronta las diversas posiciones de ambos maestros sobre el tema, analizando aproximaciones y divergencias en función de la base común ejemplarista, para arribar a una posible solución en el marco de la teoría de los trascendentales.

Un rasgo medieval de la tolerancia en Buenaventura : la cohibitio

En diversos pasajes de su Comentario a las Sentencias Buenaventura aborda el tema de las faltas veniales incorporando, en un marco teológico, una acepción del concepto de tolerancia heredada de los victorinos, el de ‘cohibitio’, para indicar un aspecto de la permisión que, por oposición al concepto de ‘prohibitio’, señalaría la posibilidad de tolerar una falta venial con el fin de evitar un mal mayor. Este trabajo presenta un seguimiento del concepto de cohibitio en los usos previos a Buenaventura, y señala en este último la vinculación de la tolerancia con el resto de las virtudes mediante la forma común o ‘forma directiva’: la caridad, que otorga a las virtudes un complemento en su ordenación natural al Bien como fin último. En este contexto, se muestra asimismo cómo la estructura conceptual de la teoría de las virtudes en Buenaventura sigue un esquema filosófico que encuentra su fundamentación metafísica en la unidad de los trascendentales.

Stable oxygen isotopes of Globigerinoides ruber and biostratigraphic datums at ODP Site 165-1002

Ocean Drilling Program Site 1002 in the Cariaco Basin was drilled in the final two days of Leg 165 with only a short transit remaining to the final port of San Juan, Puerto Rico. Because of severe time constraints, cores from only the first of the three long replicate holes (Hole 1002C) were opened at sea for visual description, and the shipboard sampling was restricted to the biostratigraphic examination of core catchers. The limited sampling and general scarcity of biostratigraphic datums within the late Quaternary interval covered by this greatly expanded hemipelagic sequence resulted in a very poorly defined age model for Site 1002 as reported in the Leg 165 Initial Reports volume of the Proceedings of the Ocean Drilling Program. Here, we present for the first time a new integrated stratigraphy for Site 1002 based on the standard of late Quaternary oxygen-isotope variations linked to a suite of refined biostratigraphic datums. These new data show that the sediment sequence recovered by Leg 165 in the Cariaco Basin is continuous and spans the time interval from 0 to ~580 ka, with a basal age roughly twice as old as initially suspected from the tentative shipboard identification of a single biostratigraphic datum. Lithologic subunits recognized at Site 1002 are here tied into this new stratigraphic framework, and temporal variations in major sediment components are reported. The biogenic carbonate, opal, and organic carbon contents of sediments in the Cariaco Basin tend to be high during interglacials, whereas the terrigenous contents of the sediments increase during glacials. Glacioeustatic variations in sea level are likely to exert a dominant control on these first-order variations in lithology, with glacial surface productivity and the nutrient content of waters in the Cariaco Basin affected by shoaling glacial sill depths, and glacial terrigenous inputs affected by narrowing of the inner shelf and increased proximity of direct riverine sources during sea-level lowstands.