Petrography, microprobe analyses and isotope composition of ultramafic rock from the northern Haskard Highlands, Shackleton Range, East Antarctica

In the Shackleton Range of East Antarctica, garnet-bearing ultramafic rocks occur as lenses in supracrustal high-grade gneisses. In the presence of olivine, garnet is an unmistakable indicator of eclogite facies metamorphic conditions. The eclogite facies assemblages are only present in ultramafic rocks, particularly in pyroxenites, whereas other lithologies - including metabasites - lack such assemblages. We conclude that under high-temperature conditions, pyroxenites preserve high-pressure assemblages better than isofacial metabasites, provided the pressure is high enough to stabilize garnet-olivine assemblages (i.e. >=18-20 kbar). The Shackleton Range ultramafic rocks experienced a clockwise P-T path and peak conditions of 800-850 °C and 23-25 kbar. These conditions correspond to ~70 km depth of burial and a metamorphic gradient of 11-12 °C/km that is typical of a convergent plate-margin setting. The age of metamorphism is defined by two garnet-whole-rock Sm-Nd isochrons that give ages of 525 ± 5 and 520 ± 14 Ma corresponding to the time of the Pan-African orogeny. These results are evidence of a Pan-African suture zone within the northern Shackleton Range. This suture marks the site of a palaeo-subduction zone that likely continues to the Herbert Mountains, where ophiolitic rocks of Neoproterozoic age testify to an ocean basin that was closed during Pan-African collision. The garnet-bearing ultramafic rocks in the Shackleton Range are the first known example of eclogite facies metamorphism in Antarctica that is related to the collision of East and West Gondwana and the first example of Pan-African eclogite facies ultramafic rocks worldwide. Eclogites in the Lanterman Range of the Transantarctic Mountains formed during subduction of the palaeo-Pacific beneath the East Antarctic craton.

Horizontal profiles of longwave and shortwave radiation components over sea ice near Barrow, Alaska during the 2011 melt

An integrated instrument package for measuring and understanding the surface radiation budget of sea ice is presented, along with results from its first deployment. The setup simultaneously measures broadband fluxes of upwelling and downwelling terrestrial and solar radiation (four components separately), spectral fluxes of incident and reflected solar radiation, and supporting data such as air temperature and humidity, surface temperature, and location (GPS), in addition to photographing the sky and observed surface during each measurement. The instruments are mounted on a small sled, allowing measurements of the radiation budget to be made at many locations in the study area to see the effect of small-scale surface processes on the large-scale radiation budget. Such observations have many applications, from calibration and validation of remote sensing products to improving our understanding of surface processes that affect atmosphere-snow-ice interactions and drive feedbacks, ultimately leading to the potential to improve climate modelling of ice-covered regions of the ocean. The photographs, spectral data, and other observations allow for improved analysis of the broadband data. An example of this is shown by using the observations made during a partly cloudy day, which show erratic variations due to passing clouds, and creating a careful estimate of what the radiation budget along the observed line would have been under uniform sky conditions, clear or overcast. Other data from the setup's first deployment, in June 2011 on fast ice near Point Barrow, Alaska, are also shown; these illustrate the rapid changes of the radiation budget during a cold period that led to refreezing and new snow well into the melt season.

Alkenone-derived sea surface temperature records of three sediment cores from the southern Benguela upwelling system

We present alkenone-derived Sea Surface Temperature (SST) records from three marine cores collected within the southern Benguela Upwelling System (BUS) spanning the last 3 ka. The SST evolution over the last 3 millennia is marked by aperiodic millennial-scale oscillations that broadly correspond to climatic anomalies identified over the North Atlantic region. The BUS SST data further suggest cooling and warming trends opposite to the temperature evolution in the Moroccan upwelling region and in Antarctica. In contrast, the last decades are marked by a cooling of unprecedented magnitude in both the Benguela and Moroccan upwelling systems, which is not observed in the Antarctic record. These contrasted responses in Atlantic upwelling systems triggered by natural and anthropogenic forcings shed light on how different climatic mechanisms are mediated by ocean-atmosphere interactions and transmitted to the geological records of past and present climate changes.

J'Marcuse : La tarea intelectual de Herbert Marcuse ante la sociedad unidimensional

El propósito de la ponencia es reconstruir el vínculo entre el derrotero teórico de Herbert Marcuse y su diagnóstico de la sociedad norteamericana. Más específicamente, el objetivo es comprender las versiones contrastantes de Estados Unidos que conviven en la obra del autor a la luz de su preocupación por el papel de la teoría crítica en los procesos de transformación social. En primer término, se examina el lugar preponderante que ocupa Estados Unidos en el estudio de las sociedades industriales avanzadas emprendido por Marcuse en El hombre unidimensional. En esta sección, se presta particular atención al problema de la vigencia de la teoría crítica en el marco de una sociedad que, como la norteamericana, parece capaz de fagocitar las fuerzas tendientes al cambio social. En segundo término, la ponencia analiza cómo la irrupción de nuevas corrientes contestatarias en la escena cultural y política norteamericana modificó la visión de Marcuse sobre los Estados Unidos, así como las reformulaciones conceptuales implicadas en ese viraje. Para finalizar, la deriva intelectual y política de Marcuse por Estados Unidos se coteja con la de Theodor W. Adorno, propiciando una reflexión acerca de sus modos contrastantes de comprender y ejercer la teoría crítica

J'Marcuse : La tarea intelectual de Herbert Marcuse ante la sociedad unidimensional

El propósito de la ponencia es reconstruir el vínculo entre el derrotero teórico de Herbert Marcuse y su diagnóstico de la sociedad norteamericana. Más específicamente, el objetivo es comprender las versiones contrastantes de Estados Unidos que conviven en la obra del autor a la luz de su preocupación por el papel de la teoría crítica en los procesos de transformación social. En primer término, se examina el lugar preponderante que ocupa Estados Unidos en el estudio de las sociedades industriales avanzadas emprendido por Marcuse en El hombre unidimensional. En esta sección, se presta particular atención al problema de la vigencia de la teoría crítica en el marco de una sociedad que, como la norteamericana, parece capaz de fagocitar las fuerzas tendientes al cambio social. En segundo término, la ponencia analiza cómo la irrupción de nuevas corrientes contestatarias en la escena cultural y política norteamericana modificó la visión de Marcuse sobre los Estados Unidos, así como las reformulaciones conceptuales implicadas en ese viraje. Para finalizar, la deriva intelectual y política de Marcuse por Estados Unidos se coteja con la de Theodor W. Adorno, propiciando una reflexión acerca de sus modos contrastantes de comprender y ejercer la teoría crítica

J'Marcuse : La tarea intelectual de Herbert Marcuse ante la sociedad unidimensional

El propósito de la ponencia es reconstruir el vínculo entre el derrotero teórico de Herbert Marcuse y su diagnóstico de la sociedad norteamericana. Más específicamente, el objetivo es comprender las versiones contrastantes de Estados Unidos que conviven en la obra del autor a la luz de su preocupación por el papel de la teoría crítica en los procesos de transformación social. En primer término, se examina el lugar preponderante que ocupa Estados Unidos en el estudio de las sociedades industriales avanzadas emprendido por Marcuse en El hombre unidimensional. En esta sección, se presta particular atención al problema de la vigencia de la teoría crítica en el marco de una sociedad que, como la norteamericana, parece capaz de fagocitar las fuerzas tendientes al cambio social. En segundo término, la ponencia analiza cómo la irrupción de nuevas corrientes contestatarias en la escena cultural y política norteamericana modificó la visión de Marcuse sobre los Estados Unidos, así como las reformulaciones conceptuales implicadas en ese viraje. Para finalizar, la deriva intelectual y política de Marcuse por Estados Unidos se coteja con la de Theodor W. Adorno, propiciando una reflexión acerca de sus modos contrastantes de comprender y ejercer la teoría crítica

ODP Site 162-980 age model and color reflectance record of sediments from ODP Leg 162 sites

Sediment spectral reflectance measurements were generated aboard the JOIDES Resolution during Ocean Drilling Program Leg 162 shipboard operations. The large size of the raw data set (over 1.3 gigabytes) and limited computer hard disk storage space precluded detailed analysis of the data at sea, although broad band averages were used as aids in developing splices and determining lithologic boundaries. This data report describes the methods used to collect these data and their shipboard and postcruise processing. These initial results provide the basis for further postcruise research.