Age determination, sedimentological, biogeochemical, and plant macrofossils analyses of outcrop PG2038-1

Thermokarst lakes are a widespread feature of the Arctic tundra, in which highly dynamic processes are closely connected with current and past climate changes. We investigated late Quaternary sediment dynamics, basin and shoreline evolution, and environmental interrelations of Lake El'gene-Kyuele in the NE Siberian Arctic (latitude 71°17'N, longitude 125°34'E). The water-body displays thaw-lake characteristics cutting into both Pleistocene Ice Complex and Holocene alas sediments. Our methods are based on grain size distribution, mineralogical composition, TOC/N ratio, stable carbon isotopes and the analysis of plant macrofossils from a 3.5-m sediment profile at the modern eastern lake shore. Our results show two main sources for sediments in the lake basin: terrigenous diamicton supplied from thermokarst slopes and the lake shore, and lacustrine detritus that has mainly settled in the deep lake basin. The lake and its adjacent thermokarst basin rapidly expanded during the early Holocene. This climatically warmer than today period was characterized by forest or forest tundra vegetation composed of larches, birch trees and shrubs. Woodlands of both the HTM and the Late Pleistocene were affected by fire, which potentially triggered the initiation of thermokarst processes resulting later in lake formation and expansion. The maximum lake depth at the study site and the lowest limnic bioproductivity occurred during the longest time interval of ~7 ka starting in the Holocene Thermal Maximum and lasting throughout the progressively cooler Neoglacial, whereas partial drainage and an extensive shift of the lake shoreline occurred ~0.9 cal. ka BP. Correspondingly, this study discusses different climatic and environmental drivers for the dynamics of a thermokarst basin.

Pulsión, libido, la hermeneútica y la energética

El trabajo se enmarca en el estudio de la teoría psicoanalítica, sus conceptos y desarrollos, según el establecimiento de dos ejes conceptuales a partir de los cuales se desarrollaran los temas particulares: el eje hermenéutico y el eje energético, tales ejes corresponderían en el marco de la orientación lacaniana a los ejes del sentido y del goce; este tipo de ordenamiento ya ha sido utilizado (con diferentes funciones) por autores como Ricoeur, Aussoun y J-A. Miller, entre otros. En el presente trabajo, se procura poner a prueba la eficacia de los dos ejes mencionados para situar de modo más preciso y ayudar al entendimiento de algunos conceptos de la teoría psicoanalítica y sus incidencias en la comprensión de los fenómenos clínicos. A partir de estos dos ejes, cuya aplicación puede ser más general o diversa, se realiza un abordaje de la explicación de los sueños y también de los síntomas (especialmente los neuróticos) en la obra de Freud. Se destaca la novedad freudiana respecto de los criterios elegidos para este trabajo señalándose que en lo que respecta al sentido la novedad radica en sostener y probar que los síntomas neuróticos poseen un valor de mensaje desfigurado, que son susceptibles de un desciframiento, y en el caso de los sueños, si bien este aspecto está presente, es la organización según el principio del placer como regulador de la energética de las formaciones psíquicas lo que importa la mayor novedad de la perspectiva freudiana. En el mismo sentido, luego de situar de modo general el concepto de libido, se procede a abordar la utilización que Freud hizo del mismo en las primeras conceptualizaciones señalando que lo trata fundamentalmente como un elemento de la energética psíquica. El recorrido argumentativo pasará luego a tratar el concepto de pulsión, de aparición más tardía en la teoría, ligado al de libido y muchas veces confundido con él. En relación a este concepto, se intenta demostrar la importancia del giro que implica la puesta en protagonismo del eje hermenéutico para el entendimiento de la teoría y la clínica psicoanalítica, perspectiva que será radicalizada en el marco de la orientación lacaniana. Siguiendo esta última orientación, se demuestra que la pulsión sexual en psicoanálisis resulta de la profunda transformación que implica la inserción del ser humano en un mundo de lenguaje, de sentido. Se acompaña el recorrido que Lacan plantea a lo largo de 'El Seminario: libro 11' según los conceptos de: necesidad, demanda, deseo, demanda de amor y finalmente el de pulsión, entendida como un montaje. En este último sentido se establecerá que el aspecto energético de la pulsión es solamente un componente de la misma; se procurará también clarificar y ejemplificar la importancia de los elementos de sentido, de la incidencia de los elementos significantes para la mejor comprensión de este concepto de gran relevancia en la clínica psicoanalítica. Para cernir el concepto de pulsión sexual según la prevalencia del criterio hermenéutico en la obra de Freud se tomará como referencia texto 'Sobre las trasposiciones de la pulsión, en particular del erotismo anal'

Pollen and macrofossils profiles and age determination from three cores in Northeastern Kansas, U.S.A.

Two marshes near Muscotah and Arrington, Atchison County, northeastern Kansas, yielded a pollen sequence covering the last 25,000 yrs of vegetation development. The earliest pollen spectra are comparable with surface pollen spectra from southern Saskatchewan and southeastern Manitoba and might indicate a rather open vegetation but with some pine, spruce, and birch as the most important tree species, with local stands of alder and willow. This type of vegetation changed about 23,000 yrs ago to a spruce forest, which prevailed in the region until at least 15,000 yrs ago. Because of a hiatus, the vegetation changes resulting in the spread of a mixed deciduous forest and prairie, which was present in the region from 11,000 to 9,000 yrs ago, remain unknown. Prairie vegetation, with perhaps a few trees along the valleys, covered the region until about 5,000 yrs ago, when a re-expansion of deciduous trees began in the lowlands.

Mineralogy and diagenesis: Their effect on acoustic and electrical properties of pelagic clays at DSDP Leg 86 Holes

Analysis of pelagic clay samples from Sites 576, 578, and 581 shows that physical, acoustic, and electrical trends with increasing burial depth are related to mineralogical and diagenetic changes. The properties of interest are bulk density (roo), porosity (phi), compressional-wave velocity (Vp) and velocity anisotropy (Ap), and electrical resistivity (Ro) and resistivity anisotropy (Ar). In general, as demonstrated in particular for the brown pelagic clay, the increase in roo, Vp, Ro, and to a lesser extent Ap and Ar with increasing depth is primarily caused by decreasing phi (and water content) as a result of compaction. The mineralogy and chemistry of the pelagic clays vary as a function of burial depth at all three sites. These variations are interpreted to reflect changes in the relative importance of detrital and diagenetic components. Mineralogical and chemical variations, however, play minor roles in determining variations in acoustic and electrical properties of the clays with increasing burial depth.

Pulsión, libido, la hermeneútica y la energética

El trabajo se enmarca en el estudio de la teoría psicoanalítica, sus conceptos y desarrollos, según el establecimiento de dos ejes conceptuales a partir de los cuales se desarrollaran los temas particulares: el eje hermenéutico y el eje energético, tales ejes corresponderían en el marco de la orientación lacaniana a los ejes del sentido y del goce; este tipo de ordenamiento ya ha sido utilizado (con diferentes funciones) por autores como Ricoeur, Aussoun y J-A. Miller, entre otros. En el presente trabajo, se procura poner a prueba la eficacia de los dos ejes mencionados para situar de modo más preciso y ayudar al entendimiento de algunos conceptos de la teoría psicoanalítica y sus incidencias en la comprensión de los fenómenos clínicos. A partir de estos dos ejes, cuya aplicación puede ser más general o diversa, se realiza un abordaje de la explicación de los sueños y también de los síntomas (especialmente los neuróticos) en la obra de Freud. Se destaca la novedad freudiana respecto de los criterios elegidos para este trabajo señalándose que en lo que respecta al sentido la novedad radica en sostener y probar que los síntomas neuróticos poseen un valor de mensaje desfigurado, que son susceptibles de un desciframiento, y en el caso de los sueños, si bien este aspecto está presente, es la organización según el principio del placer como regulador de la energética de las formaciones psíquicas lo que importa la mayor novedad de la perspectiva freudiana. En el mismo sentido, luego de situar de modo general el concepto de libido, se procede a abordar la utilización que Freud hizo del mismo en las primeras conceptualizaciones señalando que lo trata fundamentalmente como un elemento de la energética psíquica. El recorrido argumentativo pasará luego a tratar el concepto de pulsión, de aparición más tardía en la teoría, ligado al de libido y muchas veces confundido con él. En relación a este concepto, se intenta demostrar la importancia del giro que implica la puesta en protagonismo del eje hermenéutico para el entendimiento de la teoría y la clínica psicoanalítica, perspectiva que será radicalizada en el marco de la orientación lacaniana. Siguiendo esta última orientación, se demuestra que la pulsión sexual en psicoanálisis resulta de la profunda transformación que implica la inserción del ser humano en un mundo de lenguaje, de sentido. Se acompaña el recorrido que Lacan plantea a lo largo de 'El Seminario: libro 11' según los conceptos de: necesidad, demanda, deseo, demanda de amor y finalmente el de pulsión, entendida como un montaje. En este último sentido se establecerá que el aspecto energético de la pulsión es solamente un componente de la misma; se procurará también clarificar y ejemplificar la importancia de los elementos de sentido, de la incidencia de los elementos significantes para la mejor comprensión de este concepto de gran relevancia en la clínica psicoanalítica. Para cernir el concepto de pulsión sexual según la prevalencia del criterio hermenéutico en la obra de Freud se tomará como referencia texto 'Sobre las trasposiciones de la pulsión, en particular del erotismo anal'

Anisotropy and acoustic properties at DSDP Holes 62-463 and 62-465A

Variations of acoustic properties within the sediment column may significantly affect the propagation of acoustic energy in the upper portion of the oceanic crust. Moreover, the acoustic properties of sediments reflect their mineral compositions, fabrics, and degrees of compaction and cementation. Hence, the physical properties of indurated deep-sea sediments are of considerable geophysical and geological interest. Chalks and limestones are particularly important because substantial accumulations of biogenic carbonates are generally present at the base of the deep-sea sediment column, and high-standing features such as Hess Rise are capped by calcareous deposits. This paper constitutes a preliminary report of the compressional-wave velocities and densities of 31 indurated calcareous sediment samples recovered at DSDP Sites 463 and 465, in the Mid-Pacific Mountains and on Hess Rise, respectively. The sample set includes nine pairs of samples in which velocities were measured parallel and perpendicular to bedding to determine the velocity anisotropy of the sediment. This research is part of an ongoing study of the seismic properties of indurated deep-sea carbonates.

Pedology, geochronology, palynology and macrofossils of soil profiles in the Altdarss area, german Baltic Sea coast

A new site with Lateglacial palaeosols covered by 0.8 - 2.4 m thick aeolian sands is presented. The buried soils were subjected to multidisciplinary analyses (pedology, micromorphology, geochronology, dendrology, palynology, macrofossils). The buried soil cover comprises a catena from relatively dry ('Nano'-Podzol, Arenosol) via moist (Histic Gleysol, Gleysol) to wet conditions (Histosol). Dry soils are similar to the so-called Usselo soil, as described from sites in NW Europe and central Poland. The buried soil surface covers ca. 3.4 km**2. Pollen analyses date this surface into the late Aller0d. Due to a possible contamination by younger carbon, radiocarbon dates are too young. OSL dates indicate that the covering by aeolian sands most probably occurred during the Younger Dryas. Botanical analyses enables the reconstruction of a vegetation pattern typical for the late Allerod. Large wooden remains of pine and birch were recorded.

Chemostratigraphy (CaCO3, TOC, d13Corg) of Sinemurian black shales

The Shales-with-'Beef' and Black Ven Marls of the Charmouth Mudstone Formation (Sinemurian) exposed on the Dorset Coast in southern England (Wessex Basin) show stratigraphic variation in carbonate, organic carbon and organic-carbon isotopes. Little environmental significance is attached to the variation of carbonate except in the case of the tabular and nodular limestones interrupting the sequence that probably record stratigraphic condensation and/or sedimentary stillstands that, in an extreme case, were accompanied by sea-floor erosion to produce the bored and encrusted 'Coinstone'. Relatively high total organiccarbon (TOC) contents are present in the laminated mudstones of the lower turneri Zone (upper brooki and lower birch Subzones) and the obtusum Zone (obtusum and stellare Subzones). Basin stratification related to fresh-water influx was the most likely aid to deoxygenation and enhanced preservation of organic matter. The organic-carbon isotope curve (d13Corg), which shows positive excursions in the upper turneri Zone (upper birchi Subzone) and highest obtusum - raricostatum Zones (highest stellare Subzone, densinodulum and lower raricostatoides Subzones), does not correlate with the TOC stratigraphy and was clearly not controlled by local patterns of organic-matter burial. Long-term (hundreds-of-thousands of years) variations in the carbon-isotope (d13Corg) curve are interpreted as reflecting changing seawater isotopic composition and, in the case of the stratigraphically higher interval, may be related to marine organic-carbon burial on the margins of the proto-Atlantic, as exemplified by the Lusitanian Basin in Portugal. Correlation of the carbon-isotope profile with putative sea-level curves is problematic in detail, although significant local transgressive pulses in the turneri and late raricostatum Zones are approximately coincident with positive d13Corg excursions.

Compressional and shear wave velocities and elastic constants at DSDP Leg 59 Holes

Prior to the Deep Sea Drilling Project the composition of the oceanic crust could only be inferred from seismic-refraction and gravity data and the recovery of a wide variety of dredged rocks. Through the success of the Deep Sea Drilling Project, it is now clear that the top of oceanic Layer 2 usually consists of basalt. Several laboratory studies (e.g., Fox et al., 1972; Christensen and Shaw, 1970; Hyndman and Drury, 1976) have demonstrated that the seismic velocities of oceanic basalt are similar to velocities reported from refraction studies of Layer 2 and that the variability in Layer 2 velocities has many causes, the most important being fracturing and sea-floor alteration produced by the interaction of basalt and sea water (Christensen and Salisbury, 1973). To date, most reported measurements of velocities in oceanic basalts are from samples obtained from the main ocean basins. With the exception of an earlier study of velocities and related elastic properties of a suite of rocks from DSDP Sites 292, 293, 294, and 296 located in the Philippine Sea (Christensen et al., 1975; Fountain et al., 1975), elastic properties have not been determined for oceanic rocks from marginal basins. In this chapter compressional- and shear-wave velocities and elastic constants are reported at elevated confining pressures for basalt and volcanic breccias from Holes 447A, 448, and 448A.

Carbon/Nitrogen ratio of plant tissues and biomass of belowground consumers after 11 years of experimental treatment, Toolik lake

Theory and observation indicate that changes in the rate of primary production can alter the balance between the bottom-up influences of plants and resources and the top-down regulation of herbivores and predators on ecosystem structure and function. The Exploitation Ecosystem Hypothesis (EEH) posited that as aboveground net primary productivity (ANPP) increases, the additional biomass should support higher trophic levels. We developed an extension of EEH to include the impacts of increases in ANPP on belowground consumers in a similar manner as aboveground, but indirectly through changes in the allocation of photosynthate to roots. We tested our predictions for plants aboveground and for phytophagous nematodes and their predators belowground in two common arctic tundra plant communities subjected to 11 years of increased soil nutrient availability and/or exclusion of mammalian herbivores. The less productive dry heath (DH) community met the predictions of EEH aboveground, with the greatest ANPP and plant biomass in the fertilized plots protected from herbivory. A palatable grass increased in fertilized plots while dwarf evergreen shrubs and lichens declined. Belowground, phytophagous nematodes also responded as predicted, achieving greater biomass in the higher ANPP plots, whereas predator biomass tended to be lower in those same plots (although not significantly). In the higher productivity moist acidic tussock (MAT) community, aboveground responses were quite different. Herbivores stimulated ANPP and biomass in both ambient and enriched soil nutrient plots; maximum ANPP occurred in fertilized plots exposed to herbivory. Fertilized plots became dominated by dwarf birch (a deciduous shrub) and cloudberry (a perennial forb); under ambient conditions these two species coexist with sedges, evergreen dwarf shrubs, and Sphagnum mosses. Phytophagous nematodes did not respond significantly to changes in ANPP, although predator biomass was greatest in control plots. The contrasting results of these two arctic tundra plant communities suggest that the predictions of EEH may hold for very low ANPP communities, but that other factors, including competition and shifts in vegetation composition toward less palatable species, may confound predicted responses to changes in productivity in higher ANPP communities such as the MAT studied here.

Post-glacial pollen record from Yorkshire

The stratigraphy and pollen analysis of the deposits show that this is a lake basin which during the Late-glacial period was partially filled by lake clays and muds. One of the main interests of the pollen diagrams lies in the division of zone i into three suh-zones showing a minor climatic oscillation which seems to be comparable with the Boiling oscillation of northern Europe. During Post-glacial time the greater part of the deposits has been muds but on one side a fen developed which in early zone VI was sufficiently dry to support birch and pine wood. Later in zone VI the water table must have risen slightly because the fen peats were gradually covered by a rather oxidized mud suggesting that the fen became replaced by a shallow swamp with a widely fluctuating water table. In the Atlantic period the basin was reflooded and the more central deposits were covered by a layer of mud. Later in the central region, swamp and eventually Sphagnum bog communities developed. The whole area is now covered by a sihy soil and forms a flat meadowland.