Aerosols over the Arabian Sea

This paper provides an overview of dust transport pathways and concentrations over the Arabian Sea during 1995. Results indicate that the transport and input of dust to the region is complex, being affected by both temporally and spatially important processes. Highest values of dust were found off the Omani coast and in the entrance to the Gulf of Oman. Dust levels were generally lower in summer than the other seasons, although still relatively high compared to other oceanic regions. The Findlater jet, rather than acting as a source of dust from Africa, appears to block the direct transport of dust to the open Arabian Sea from desert dust source regions in the Middle East and Iran/Pakistan. Dust transport aloft, above the jet, rather than at the surface, may be more important during summer. In an opposite pattern to dust, sea salt levels were exceedingly high during the summer monsoon, presumably due to the sustained strong surface winds. The high sea salt aerosols during the summer months may be impacting on the strong aerosol reflectance and absorbance signals over the Arabian Sea that are detected by satellite each year.

Eocene-Oligocene calcareous nannofossil events of ODP Sites from the Southern Ocean

The evolution of the Southern Ocean climate during the late Eocene-late Oligocene interval is examined through highresolution, quantitative calcareous nannofossil analyses on samples from the Southern Ocean sections on Maud Rise and Kerguelen Plateau. We determined the abundance patterns of the counted species to clarify the biostratigraphy, which we correlated with high-resolution magnetostratigraphy [Roberts, A.P., Bicknell, S.J., Byatt, J., Bohaty, S.M., Florindo, F., Harwood, D.M., 2003a. Magnetostratigraphic calibration of Southern Ocean diatom datums from the Eocene-Oligocene of Kerguelen Plateau (Ocean Drilling Program Sites 744 and 748). In: Florindo, F., Cooper, A.K., O'Brien, P.A. (Eds.), Antarctic Cenozoic Palaeoenvironments: Geologic Record and Models. Palaeogeogr., Palaeoclimatol., Palaeoecol. 198 145-168; Florindo, F., Roberts, A.P., in press. Eocene-Oligocene magnetobiochronology of ODP Sites 689 and 690, Maud Rise, Weddell Sea, Antarctica. Geol. Soc. Am. Bull.], and used this data to interpret paleoceanographic changes through the late Eocene to late Oligocene. Percentage plots of the individual species, compared with R-mode principal component and cluster analysis results, allowed us to divide the assemblages into three groups: temperate-water taxa, cool-water taxa, and no temperature-affinity taxa. We attempt correlations between these paleoecological groups and the major sea-surface temperature (SST) variations with tectonic and paleoceanographic changes in the Southern Ocean. During the late Eocene, the nannofossil assemblage data reveal that there were several minor SST decreases (coolings) from 36 to 34 Ma, before the Eocene/Oligocene (E/O) boundary. A sharp cooling event, dated at 33.54 Ma (earliest Oligocene), occurred about 160 kyr after the E/O boundary, which is dated at 33.7 Ma. Relatively stable, cool conditions are interpreted to persist until the latest Oligocene, when an increase in abundance of temperate-water taxa, which corresponds to an antithetical decrease in abundance of cool-water indicators, is recorded. On the basis of our dating, the opening of the Drake Passage, allowing shallow-water circulation, began by 33.54 Ma at the latest, while the establishment of deep-water connections through the Tasmanian Gateway occurred at 33 Ma, as suggested by Exon et al. [Proc. ODP, Init. Rep. 189 (2001) 1].

Algunos aportes teórico-metodológicos para el estudio de las inundaciones en el sur de la provincia de Córdoba

En el marco de la propuesta de Proyecto de Tesis Doctoral aprobado por el Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET) "Riesgo, agua y conflictos territoriales. El peso de las herencias en las inundaciones del sur de la provincia de Córdoba", surge la inquietud de explorar alternativas para enriquecer las metodologías empleadas, repensando las categorías de análisis espacio geográfico, territorio y medio ambiente a través de su imbricación con las dimensiones de análisis de la teoría social del riesgo (Natenzon, C., 1995; Natenzon, C., 1998) desde una perspectiva de responsabilidad social. En el sur de la provincia de Córdoba (Rep. Argentina), como numerosas regiones del país, se producen recurrentes inundaciones que afectan tanto el ámbito rural como sus localidades. En esta propuesta se pretende poner a discusión aproximaciones teóricas-metodológicas que permitan abordar el problema de las inundaciones construyendo una estructura conceptual simbólica que sea significativa para desentrañar las responsabilidades sociales en las lógicas de la construcción del territorio y su incidencia en la problemática a través de algunos ejemplos de prácticas constituyentes.

Algunos aportes teórico-metodológicos para el estudio de las inundaciones en el sur de la provincia de Córdoba

En el marco de la propuesta de Proyecto de Tesis Doctoral aprobado por el Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET) "Riesgo, agua y conflictos territoriales. El peso de las herencias en las inundaciones del sur de la provincia de Córdoba", surge la inquietud de explorar alternativas para enriquecer las metodologías empleadas, repensando las categorías de análisis espacio geográfico, territorio y medio ambiente a través de su imbricación con las dimensiones de análisis de la teoría social del riesgo (Natenzon, C., 1995; Natenzon, C., 1998) desde una perspectiva de responsabilidad social. En el sur de la provincia de Córdoba (Rep. Argentina), como numerosas regiones del país, se producen recurrentes inundaciones que afectan tanto el ámbito rural como sus localidades. En esta propuesta se pretende poner a discusión aproximaciones teóricas-metodológicas que permitan abordar el problema de las inundaciones construyendo una estructura conceptual simbólica que sea significativa para desentrañar las responsabilidades sociales en las lógicas de la construcción del territorio y su incidencia en la problemática a través de algunos ejemplos de prácticas constituyentes.

Cuestiones agrarias regionales

Tabla de contenidos: Cuestión agrícola y cuestión agraria en la Región Pampeana [Rep. Argentina] / Roberto Ringuelet. La producción hortícola en el Partido de La Plata : Cuestión productiva, cuestión social y cuestión ambiental / Roberto Ringuelet, Silvia Attademo, Adriana Archenti. Producción hortícola y sector informal / Roberto Ringuelet, María Cristina Salva, Silvia Attademo. Tiempo de medianero / Roberto Ringuelet, Adriana Archenti, María Cristina Salva. Categorías étnicas y relaciones sociales en colonias florícolas de la localidad de City Bell, Provincia de Buenos Aires / Horacio Sabarots.

Algunos aportes teórico-metodológicos para el estudio de las inundaciones en el sur de la provincia de Córdoba

En el marco de la propuesta de Proyecto de Tesis Doctoral aprobado por el Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET) "Riesgo, agua y conflictos territoriales. El peso de las herencias en las inundaciones del sur de la provincia de Córdoba", surge la inquietud de explorar alternativas para enriquecer las metodologías empleadas, repensando las categorías de análisis espacio geográfico, territorio y medio ambiente a través de su imbricación con las dimensiones de análisis de la teoría social del riesgo (Natenzon, C., 1995; Natenzon, C., 1998) desde una perspectiva de responsabilidad social. En el sur de la provincia de Córdoba (Rep. Argentina), como numerosas regiones del país, se producen recurrentes inundaciones que afectan tanto el ámbito rural como sus localidades. En esta propuesta se pretende poner a discusión aproximaciones teóricas-metodológicas que permitan abordar el problema de las inundaciones construyendo una estructura conceptual simbólica que sea significativa para desentrañar las responsabilidades sociales en las lógicas de la construcción del territorio y su incidencia en la problemática a través de algunos ejemplos de prácticas constituyentes.

Pollen records from Elbe-Weser Dreieck

A long-running interdisciplinary research project on the development of landscape, prehistoric habitation and the history of vegetation within a "siedlungskammer" (limited habitation areal from neolithic to modern times has been carried out in the NW German lowlands, The siedlungskammer Flögeln is situated between the rivers Weser and EIbe and comprises about 23.5 km^2. It is an isolated pleistocene area surrounded by bogs, the soils consisting mainly of poor sands. In this siedlungskammer large-seale archaeological excavations and mappings have been performed, parallel to pedological, historical and above all pollen analytical investigations. The aim of the project is to record the individual phases in time, to delimit the respective settlement areas and to reconstruct the conditions of life and economy for each time period. A dense network of 10 pollen diagrams has been constructed. Several of them derive from the marginal area and from the centre of the large raised bog north of the siedlungskammer. These diagrams reflect the history of vegetation and habitation of a large region; due to the large pollen source area the habitation phases in the diagrams are poorly defined. Even in the utmost marginal diagram of this woodless bog, a great village with adjoining fields, situated only 100 m away from it, is registered with only low values of anthropogenic indicators. In contrast to this, the numerous pollen diagrams from kettle-hole bogs inside the siedlungskammer yield an exact picture of the habitation of the siedlungskammer and their individual parts. Early traces of habitation can be identified in the pollen diagram soon after the elm decline (around 5190 BP). Some time later in the middle neolithic period there follows a marked habitation phase, which starts between 4500 and 4400 BP and reflects the immigration of the trichterbecher culture. It corresponds to the landnam phase of Iversen in Denmark and begins with a sharp decline of the pollen curves of lime and oak, followed by the increase of anthropogenic indicators pointing to arable and pastural farming. High values of wild grasses and Calluna witness extensive forest grazing. This middle to late neolithic habitation is also registered archaeologically by settlements and numerous graves. After low human activity during Bronze Age and Older Iron Age times the archaeological and pollen analytical records of Roman and Migration periods is again very strong. This is followed by a gap in habitation during the 6th and 7th centuries and afterwards in the western part of the siedlungskammer from about 700 AD until the 14th century by the activity of the medieval village of Dalem, that was also excavated and whose fields were recorded by phosphate mapping to a size of 117 hectares. This medieval settlement phase is marked by much cereal cultivation (mainly rye). The dense network of pollen diagrams offers an opportunity to register the dispersion of the anthropogenic indicators from the areas of settlement to different distances and thus to obtain quantitative clues for the assessment of these anthropogenic indicators in pollen diagrams. In fig. 4 the reflection of the neolithic culture in the kettle-hole bogs and the large raised bog is shown in 3 phases: a) pre landnam, b) TRB-landnam, c) post landnam. Among arboreal pollen the reaction of Quercus is sharp close to the settlement but is not found at more distant profiles, whilst in contrast to this Tilia shows a significant decline even far away from the settlements. The record of most anthropogenic indicators outside the habitation area is very low, in particular cereal pollen is poorly dispersed; much more certain as an indicator for habitation (also for arable farming!) is Plantago lanceolata. A strong increase of wild grasses (partly Calluna aswell) some distance from the habitation areas indicates far reaching forest grazing. Fig. 5 illustrates the reflection of the anthropogenie indicators from the medieval village Dalem. In this instance the field area could be mapped exactly using phosphate investigations, and it has been possible to indicate the precise distances of the profile sites from the medieval fields. Here also, there is a clear correlation between decreasing anthropogenic indicators and increasing distance. In a kettle-hole bog (FLH) a distance of 3000 m away this marked settlement phase is not registered. The contrast between the pollen diagrams SWK and FLH (fig. 2 + 3, enclosure), illustrates the strong differences between diagrams from kettlehole bogs close to and distant from the settlements, for the neolithic as well as for the medieval period. On the basis of the examples presented here, implications concerning the interpretation of pollen diagrams with respect to habitation phases are discussed.

Characteristic magnetizations of paleomagnetic samples from ODP Leg 103

Lower Cretaceous and Tithonian sediments were sampled for magnetostratigraphy at six holes (Holes 638B, 638C, 639A, 639D, 640A, and 641C). Magnetic polarity chrons were assigned to polarity zones using biostratigraphic constraints. In Holes 638B and 638C, polarity Chrons M3 and perhaps Ml are present in the upper part, M4 and M5 are apparently absent, M6 through M9 are poorly represented, M10 and M10N are apparently absent, and Ml 1 and M12 are tentatively assigned to the lower part. Strata in Holes 638B and 638C dip toward the south. In Hole 639A, polarity Chron M13 is well documented and M12A may be present. In Hole 639D, polarity Chrons M19 through M21 may be present, but the data is poor. Hole 640A had inadequate recovery to identify polarity chrons. In Hole 641C, polarity Chron MO is well documented and occurs significantly above the nannofossil marker of the Barremian/Aptian boundary; comparison to Italian magnetostratigraphy implies that this nannofossil datum is timetransgressive.

Paleomagneitc of early Cretaceous sediments from the western Central Atlantic

Drilling at Sites 534 and 603 of the Deep Sea Drilling Project recovered thick sections of Berriasian through Aptian white limestones to dark gray marls, interbedded with claystone and clastic turbidites. Progressive thermal demagnetization removed a normal-polarity overprint carried by goethite and/or pyrrhotite. The resulting characteristic magnetization is carried predominantly by magnetite. Directions and reliability of characteristic magnetization of each sample were computed by using least squares line-fits of magnetization vectors. The corrected true mean inclinations of the sites suggest that the western North Atlantic underwent approximately 6° of steady southward motion between the Berriasian and Aptian stages. The patterns of magnetic polarity of the two sites, when plotted on stratigraphic columns of the pelagic sediments without turbidite beds, display a fairly consistent magnetostratigraphy through most of the Hauterivian-Barremian interval, using dinoflagellate and nannofossil events and facies changes in pelagic sediment as controls on the correlations. The composite magnetostratigraphy appears to include most of the features of the M-sequence block model of magnetic anomalies from Ml to Ml ON (Barremian-Hauterivian) and from M16 to M23 (Berriasian-Tithonian). The Valanginian magnetostratigraphy of the sites does not exhibit reversed polarity intervals corresponding to Ml 1 to M13 of the M-sequence model; this may be the result of poor magnetization, of a major unrecognized hiatus in the early to middle Valanginian in the western North Atlantic, or of an error in the standard block model. Based on these tentative polarity-zone correlations, the Hauterivian/Barremian boundary occurs in or near the reversed-polarity Chron M7 or M5, depending upon whether the dinoflagellate or nannofossil zonation, respectively, is used; the Valanginian/Hauterivian boundary, as defined by the dinoflagellate zonation, is near reversed-polarity Chron M10N.