Aspectos oceanográficos sobre plataforma continental peruana en invierno de 1996. Crucero BIC SNP-1 08

Las condiciones ambientales durante el crucero 9607-08, fueron frías desde el Callao hasta Paita, con anomalías negativas de -0,8 a -2,5 °C, y ligeramente cálidas al norte de Paita registrándose anomalías de hasta +1,4 °C, en la primera etapa del crucero (evaluación acústica, del 01 al 14 de julio de 1996) y anomalías de +0,2 a -2,5° C durante la segunda etapa realizada del 15 de julio al 09 de agosto de 1996. El Frente Ecuatorial, antes del 14 de Julio se localizó al sur de Talara, replegándose luego hacia el norte y ubicándose al norte de Cabo Blanco. Las masas de Aguas Tropicales Superficiales (ATS) se ubicaron frente a Puerto Pizarro, mientras que las aguas Ecuatoriales Superficiales (AES) se ubicaron, la primera quincena de julio, al norte de Paita-Talara y, la segunda quincena, al norte de Cabo Blanco. Las aguas Subtropicales Superficiales (ASS) se localizaron frente a Pimentel - Chimbote fuera de las 40 mn, y las Aguas Costeras Frías (ACF) predominaron dentro de las 40 mn, en toda la faja costera. El afloramiento costero se desarrolló con fuerte intensidad entre Talara-Paita, Punta Falsa - Chicama y Chimbote asociados a valores menores de 16 °C de temperatura, 35,0‰ de salinidad y 3 mL/L de oxígeno disuelto.

Sedimentos superficiales del margen continental peruano: un mapa textural

La distribución de los sedimentos superficiales en el margen continental peruano se presenta en dos mapas a colores. Los sedientos arenosos predominan en la mayor parte de la amplia plataforma entre los 7º y 10º30' S, alcanzando también profundidades del talud superior. Al sur de esta área se encuentran formando parches costeros. La arcilla limosa cubre casi todo el talud continental y gran parte de la plataforma al sur de los 10º30' S; al norte de esta latitud forman algunos parches costeros. El patrón textural observado está determinado por la interacción de varios factores medio ambientales, peculiares de la región. En toda el área estudiada se produce afloramiento más o menos fuerte y se da una elevada productividad biológica. Entre los diversos factores medio ambientales que conducen a la formación de sedimentos arenosos o fangosos, las aguas bien o pobremente o dgenadas y las corrientes de fondo fuertes o débi les, respectivamente, son consiperadas las más importantes.

Textura,carbono orgánico y carbonatos de los sedimentos del margen continental peruano.

Estudio de las variaciones texturales y geoquímicas de los sedimentos del margen continental peruano.

Información básica sobre muestras de bentos, sedimentos y factores abioticos de la plataforma continental del Perú entre 1976 y 1987

Se presenta la información básica sobre un total de 455 estaciones en la plataforma continental peruana en las cuales se tomaron muestras de macrobentos. La información fue obtenida durante 13 cruceros con los barcos de investigación científica Humboldt, SNP-1 y Tareq-II así como con bolichera. Aparte de las informaciones básicas de las estaciones y los muestreos se proporcionan datos sobre el sedimento y factores abióticos de las aguas cercanas del fondo marino.

Macrozoobentos de dos Áreas de la plataforma continental del Norte Peruano en el verano de 1987

Se estudiaron muestras de Macrozoobentos (> 1 mm) tomadas a diferentes profundidades en enero de 1987 por el BIC Humboldt de la plataforma continental de dos áreas del norte del litoral peruano, una frente a zorritos (3º35.5`- 3º51.3`) y otra entre Isla Lobos de Tierra y Pimentel (6º32.0`- 6º55.5`), de distinto tipo de sedimento en el fondo. Las muestras estudiadas, así como los datos de Temperatura, Oxigeno disuelto y Salinidad en el fondo, fueron proporcionadas por el Programa Cooperativo Peruano-Alemán de Investigación Pesquera (PROCOPA) y el Instituto del Mar del Perú (IMARPE). El trabajo consiste en identificar, cuantificar y comparar las taxa presentes en las muestras de ambas áreas, determinar la Biomasa, Densidad, Diversidad, Equidad y Riqueza, y analizar el tipo y característica del sedimento de las estaciones. Para el estudio del aspecto comunitario se emplearon el análisis de agrupamiento por racimos (“cluster análisis”; Legendre y Legendre, 1983) y la técnica de los Índices Biológicos (Guille, 1970). En el análisis estadístico se usaron preferentemente la prueba no paramétrica de dos grupos de Kolmogorov-Smirnov y correlaciones lineales entre los factores abiòticos, características del sedimento y parámetros biológicos hallados.

Essad Pasha [général turc assassiné par un étudiant albanais devant l'hôtel Continental, rue de Castiglione à Paris le 13 juin 1920] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 59712

Continental margin architecture : the palynological signature of glacioeustasy /

Palynomorphs from two siliciclastic margins were examined to gain insights into continental margin architecture. Sea level change is thought to be one of the primary controls on continental margin architecture. Because Late Neogene glacioeustasy has been well studied marine sediments deposited during the Late Neogene were examined to test this concept. Cores from the outer shelf and upper slope were taken from the New Jersey margin in the western North Atlantic Ocean and from the Sunda Shelf margin in the South China Sea. Continental margin architecture is often described in a sequence stratigraphic context. One of the main goals of both coring projects was to test the theoretical sequence stratigraphic models developed by a research group at Exxon (e.g. Wilgus et al., 1988). Palynomorphs provide one of the few methods of inferring continental margin architecture in monotonous, siliciclastic marine sediments where calcareous sediments are rare (e.g. New Jersey margin). In this study theoretical models of the palynological signature expected in sediment packages deposited during the various increments of a glacioeustatic cycle were designed. These models were based on the modem palynomorph trends and taphonomic factors thought to control palynomorph distribution. Both terrestrial (pollen and spores) and marine (dinocysts) palynomorphs were examined. The palynological model was then compared with New Jersey margin and Sunda Shelf margin sediments. The predicted palynological trends provided a means of identifying a complete cycle of glacioeustatic change (Oxygen Isotope Stage 5e to present) in the uppermost 80 meters of sediment on the slope at the New Jersey margin. Sediment availability, not sea meters of sediment on the slope at the New Jersey margin. Sediment availability, not sea level change, is thought to be the major factor controlling margin architecture during the late Pleistocene here at the upper slope. This is likely a function of the glacial scouring of the continents which significantly increases sediment availability during glacial stages. The subaerially exposed continental shelf during the lowstand periods would have been subject to significant amounts of erosion fi:om the proglacial rivers flowing fi-om the southern regions of the ice-sheet. The slope site is non-depositional today and was also non-depositional during the last full interglacial period. The palynomorph data obtained fi-om the South China Sea indicate that the major difference between the New Jersey Margin sites and the Sunda Shelf margin sites is the variation in sediment supply and the rate of sediment accumulation. There was significantly less variation in sediment supply between glacial and interglacial periods and less overall sediment accumulation at the Sunda Shelf margin. The data presented here indicate that under certain conditions the theoretical palynological models allow the identification of individual sequence stratigraphic units and therefore, allow inferences regarding continental margin architecture. The major condition required in this approach is that a complete and reliable database of the contemporaneous palynomorphs be available.

Investigating Microbial Trace-fossils and Abiotic Alteration in Hydrovolcanic Tuffs of the Fort Rock Volcanic Field, Oregon

Microbial ichnofossils in volcanic rocks provide a significant record of subsurface microbes and potentially extraterrestrial biosignatures. Here, the textures, mineralogy, and geochemistry of two continental basaltic hydrovolcanic deposits - Reed Rocks and Black Hills - in the Fort Rock Volcanic Field (FRVF) are investigated. Methods include petrographic microscopy, micro and powder X-ray diffraction, SEM/BSE/EDF imaging, energy dispersive spectroscopy, stable isotopes, and X-ray fluorescence. Petrographic analysis revealed granular and tubular textures with biogenic morphologies that include terminal enlargements, septate divisions, branching forms, spiral filaments, and ovoid bodies resembling endolithic microborings described in ocean basalts. They display evidence of behaviour and a geologic context expressing their relative age and syngenicity. Differences in abiotic alteration and the abundance/morphotype assemblage of putative microborings between the sites indicate that water/rock ratio, fluid composition and flux, temperature and secondary phase formation are influences on microboring formation. This study is the first report of reputed endolithic microborings in basalts erupted in a continental lacustrine setting.

The New Continental Line Atchison, Topeka and Santa Fe Railroad West and Southwest schedule

The New Continental Line Atchison, Topeka and Santa Fe Railroad West and Southwest schedule. The schedule is slightly torn. This does not affect the text, Sept. 4, 1881.

Geochemistry of Rare Erath Elements and Trace Metals along the Western Continental Shelf of India

Rare earth elements have occupied an important role in marine geochemical research, particularly as used in the format of REE abundance patterns to describe the geochemical pathways in marine sedimentation and authigenesis. This study concentrates on the distribution pattern of Rare earth elements in the sediments, behavior of Eu and Ce with respect to their occurrence in multiple oxidation states. It also concentrate the depth wise variation of sediment REEs from near shore areas (30m) to deeper depths 200m) in the Arabian Sea. It includes the downcore variation of REEs and other trace elements in the sediment cores and a comparison between the REE distributions of Arabian Sea sediment with the sediments of Andaman Sea. The study gives a general introduction regarding the importance of RRE studies, its occurrence and abundance, electronic configuration, lanthanide contraction, oxidations states and REE supply to the ocean, seawater and sediments.

Dynamics of Rifting Along the Southwest Continental margin of India Through Coherence and Process oriented Analysis of Gravity Data

Department of Marine Geology and Geophysics,Cochin University of Science and Technology