(Table 2) Actual and synthetic mass accumulation rate data and their absolute differences for ODP Site 115-707

Synthetic mass accumulation rates have been calculated for ODP Site 707 using depth-density and depth-porosity functions to estimate values for these parameters with increasing sediment thickness, at 1 Ma time intervals determined on the basis of published microfossil datums. These datums were the basis of the age model used by Peterson and Backman (1990, doi:10.2973/odp.proc.sr.115.163.1990) to calculate actual mass accumulation rate data using density and porosity measurements. A comparison is made between the synthetic and actual mass accumulation rate values for the time interval 37 Ma to the Recent for 1 Myr time intervals. There is a correlation coefficient of 0.993 between the two data sets, with an absolute difference generally less than 0.1 g/cm**2/kyr. We have used the method to extend the mass accumulation rate analysis back to the Late Paleocene (60 Ma) for Site 707. Providing age datums (e.g. fossil or magnetic anomaly data) are available the generation of synthetic mass accumulation rates can be calculated for any sediment sequence.

Age models, accumulation rates, sand and carbonates at DSDP Leg 74 holes

Accumulation rates for the five sites drilled during Leg 74 of the Glomar Challenger are presented on a common timescale based on calibration of datum levels to paleomagnetic records in Leg 74 sediments for the Paleogene, and a new compilation by Berggren et al. (1985), for the Neogene, and using the seafloor-spreading magnetic anomaly timescale of Kent (1985). We present data on accumulation of total sediment, of foraminifers, of the noncarbonate portion, and of fish teeth that give a history of productivity, winnowing, carbonate dissolution, and nonbiogenic input to what was then a part of the South Atlantic at about 30 deg S.

Calcium carbonate, sedimentation and mass accumulation rates at DSDP Site 85-572

At Site 572, located at 1°N, 114° W (3903 m water depth), we recovered a continuous hydraulic piston cored section of upper Miocene to upper Pleistocene pelagic sediments. The sediment is composed of biogenic carbonate and silica with nonbiogenic material as a minor component. Detailed analysis of the calcium carbonate content shows that the degree of variability in carbonate deposition apparently changed markedly between the late Miocene and Pliocene at this equatorial Pacific site. During this interval carbonate mass accumulation rates decreased from 2.6 to 0.8 g/cm**2 per 10**3 yr. If we assume that variations in CaCO3 content reflect changes in the degree of dissolution, then the detailed carbonate analysis would suggest that the degree of variability in carbonate deposition decreases by a factor of 5 as the dominant wavelength of variations increases significantly. However, if the variability in carbonate concentration is described in terms of changes in mean mass accumulation, calculations then suggest that relatively small changes in noncarbonate rates may be important in controlling the observed carbonate records. In addition, the analysis suggests that the degree of variability observed in pelagic carbonate data may in part reflect total accumulation rates. Intervals with high sedimentation rates show lower amplitude variations in concentration than intervals with lower sedimentation rates for the same degree of change in the carbonate accumulation rate.

Authigenic uranium, mass accumulation rates, benthic d13C and SST during the last interglacial period of ODP Site 177-1094

Southern Ocean sediments reveal a spike in authigenic uranium 127,000 years ago, within the last interglacial, reflecting decreased oxygenation of deep water by Antarctic Bottom Water (AABW). Unlike ice age reductions in AABW, the interglacial stagnation event appears decoupled from open ocean conditions and may have resulted from coastal freshening due to mass loss from the Antarctic ice sheet. AABW reduction coincided with increased North Atlantic Deep Water (NADW) formation, and the subsequent reinvigoration in AABW coincided with reduced NADW formation. Thus, alternation of deep water formation between the Antarctic and the North Atlantic, believed to characterize ice ages, apparently also occurs in warm climates.

Sediment properties, contents and accumulation rates of Hg in cores of Upper Quaternary sediments from the Deryugin Basin, Okhotsk Sea

The Hg distribution and some mineralogical-geochemical features of bottom sediments up to a depth of 10 m in the Deryugin Basin showed that the high and anomalous Hg contents in the Holocene deposits are confined to a spreading riftogenic structure and separate fluid vents within it. The accumulations of Hg in the the sediments were caused by its fluxes from gas and low-temperature hydrothermal vents under favorable oceanological conditions in the Holocene. The two mainly responsible for the high and anomalous Hg contents are infiltration (fluxes of hydrothermal or gas fluids from the sedimentary cover) and plume (Hg precipitation from water plumes with certain hydrochemical conditions forming above endogenous sources). The infiltration anomalies of Hg were revealed in the following environments: (1) near gas vents on the northeastern Sakhalin slope, where high Hg contents are associated only with Se and were caused by the accumulation of gases ascending from beneath the gas hydrate layer; (2) in the area of inferred occasionally operating low-temperature hydrothermal seeps in the central part of the Deryugin Basin, in which massive barite chimneys, hydrothermal Fe-Mn crusts, and anomalous contents of Mn, Ba, Zn, and Ni in sediments develop.

As lavouras de grãos como atividades de desenvolvimento e integração da Região da Grande Dourados ao circuito produtivo nacional

Led to become a national productive Center, the Great Dourados Region, which consists of 40 cities located in the south of the state of Mato Grosso do Sul - Brazil, emerged as a grain productive region from the middle of the 1970s in the 20th century to the beginning of the 21st century. Using modern agricultural techniques, the land organization in this region was ruled by a development policy which was not concerned with the socio environmental aspects of the area. In this context, the present work aims to analyze the development process of the Great Dourados region, through soybean production and its relation to the confinement of the indigenous people present in the Area. This integration happened due to the money and for it, inserting this Region into a national productive pattern which guided the farmers to modern crops, mainly soybean. The land cultivation was not the only productive activity that granted the Region an economic integration, to both the national and international market. From the end of the Paraguay War (1870) to the middle of the 70s, there were at least two other ways to the regional economic integration. One of them happened with the traditional activities of cattle raising and the extraction of the Paraguay tea (maté/ Yerba Mate) from 1870 to 1937, which divided the regional territory into large farmlands focused on the external market. The other way happened with the need to create a market for the agricultural production and for the demand for manufactured goods, which reorganized the regional territory into small farmlands, as a result of colonization projects from 1943 to 1956. Since 1976, with the creation of the Special Program for the Development of the Great Dourados Region (Prodegran), the capitalist relations of production, which were consolidated in the area, were not ruled almost exclusively by the traditional activities of cattle raising and the extraction of the Paraguay tea, in order to create a new accumulation center connected to the modern crops. As this new accumulation center was created, the Region was led to a selective and dependent integration process, in which many farmers changed their accumulation centers to modern grain crops, causing environmental degradation, productive exclusion and ethnical-cultural conflicts with the indigenous community

Estado de situación del agro pampeano. Bases para teorizar sobre indicadores de vulnerabilidad socio-territorial

El estado de situación del agro pampeano desde la implantación del modelo económico neoliberal en la década del '70 hasta nuestros días, plantea el desafío de repensar las categorías de análisis que nos permitan abordar el estudio de la vulnerabilidad socio-territorial de los actores sociales implicados en el agro. Los supuestos neoliberales que han conducido el modelo de producción agropecuario de acumulación y rápida rotación de capital, especulación financiera, externalización de costos sociales y ambientales, entre otros generan situaciones de profundas desigualdades socio-territoriales, que incrementan los grados de vulnerabilidad. Resulta ineludible entonces teorizar sobre indicadores que, bajo otros supuestos, nos permitan valorar los niveles de vulnerabilidad para proponer alternativas que respondan al principio de justicia socio-territorial. Para la consecución de dicho objetivo, se parte de un análisis del estado de situación del agro en el sur cordobés; se analizan luego los supuestos neoliberales que han orientado la producción agropecuaria, para pensar caminos alternativos al modelo de capitalismo agrario, a fin de realizar nuestro aporte a la discusión sobre la construcción de indicadores de vulnerabilidad socio-territorial.