Annotated record of the detailed examination of Mn deposits from SOMIRMAS cruise stations

The cores and dredges described at this site were taken on the SOMIRMAS cruise from 5 July to 14 August 1990 by the MusÈum National d'Histoire Naturelle from the R/V Marion Dufresne. A total of 30 cores and dredges were recovered and are available at MNHN for sampling and study.

Annotated record of the detailed examination of Mn deposits from SEYMAMA-SHIVA cruise stations

The cores and dredges described at this site were taken on the SEYMAMA-SHIVA cruise from 17 August to 14 September 1990 by the MusÈum National d'Histoire Naturelle from the R/V Marion Dufresne. A total of 33 cores and dredges were recovered and are available at MNHN for sampling and study.

Do Foreign Currency Deposits Promote or Deter Financial Development in Low-Income Countries? An Empirical Analysis of Cross-Country Data

Foreign currency deposits (FCD) are prevalent in many low-income developing countries, but their impact on bank lending has rarely been examined. An examination of cross-country data indicates that a higher proportion of FCD in total deposits is associated with growth in private credit only in inflationary circumstances (over 24 percent of the annual inflation rate). FCD can lead to a decline in private credit below this threshold level of inflation. Given that FCD exhibit persistence, deregulating them in low-income countries may do more harm than good on financial development in the long term, notably after successful containment of inflation.

Be-and Emerald Deposits of the Central Urals (Russia): Conditions of Formation

The Be- and emerald deposits of the Emerald Mines region, in the central part of the Upper-Paleozoic Uralian orogen (Russia), are related to a major shear zone of N-S direction, where both Be-rich S-type granitoids (Carboniferous to Permian) and Cr-rich rocks (ophiolitic dunites and peridotes, Silurian to Devonian) are present.

New data on the ophiolitic VMS deposits of Moeche (Cabo Ortegal Complex, NW Spain)

As a result of the variscan collision, several allochtonous complexes were emplaced on the Iberian margin in Devonian times, among them the Cabo Ortegal Complex comprising the Moeche ophiolitic sequence. Copper has been won from several mines (Piquitos I & II, Barqueira, Maruxa) from disseminated ores and thin massive sulphide layers in the Moeche Unit, a strongly deformed meta-volcanic sequence comprising mainly quartz-chlorite schists and mylonites, which defines the top of the ophiolite. The ores were metamorphosed and strongly deformed under brittle conditions (for pyrite), but their textures are often apparently post-deformational, due to very common solution-transfer processes; they are composed mostly of pyrite and chalcopyrite, with minor sphalerite, pyrrhotite, etc., and with traces of native gold and PGE. The geology, mineralogy, and geochemistry of the orebodies relate closely to VMS of the Cu-Zn (Cyprus) type. Fluid inclusion studies allowed an estimation of metamorphic conditions at pressures of 2/2’5 kb and T 325/350ºC. New determinations using the chlorite geothermometer yield temperatures around 320 ºC, corresponding to pressures near 2 kb according to the isochores deduced from the fluid inclusion study, although in the Barqueira mine higher temperatures, up to 350 ºC, are found, corresponding to presssures up to 2’5 kb. Pb isotopic compositions of pyrite point to a double source of Pb, i.e. a main mantle and a subordinate crustal source. The values for 87SR/86Sr in pyrite support this interpretation, but some results suggest later mobilization in an open system, corresponding to solution-transfer. Age determinations of pyrite deduced from the Pb isotope uranogenic graph, ≈ 480 Ma, do not fit with the metamorphic ages published for the Moeche Unit, and might point to the age of Pb extraction from the mantle.

Las tobas cuaternarias del río Añamaza (provincia de Soria, Cordillera Ibérica): aproximación cronológica

High-gradient, stepped fluvial tufa systems with dammed areas existed in the River Añamaza valley (NW Iberian Ranges, Spain) during Quaternary times. Single deposits range from a few meters to about 70 m thick, in which prograding-aggrading wedges separated by erosional surfaces exist. Several episodes of tufa formation have been distinguished by means of U-series, Amino-acid racemization and radiocarbon techniques. These correlate to MIS 8, 7, 5 and 1. The presence of MIS 9 is uncertain, as chronological data may also correspond to older stages. Most tufas in this area formed in MIS 5. Distinct tufa episodes can also be distinguished in the Holocene. These are the first chronological data presented for one of the northernmost Quaternary tufa systems in the Iberian Ranges.

Canales, obras hidráulicas y proyectos de navegación fluvial: reconcialiación del Manzanares con la Ciudad de Madrid

Tras el periodo reciente, de casi cincuenta años, como autovía de circunvalación, la operación urbanística Madrid Río ha vuelto a reconciliar al Manzanares con la ciudad de Madrid. Ese medio siglo arranca en el decenio de 1930, fecha de su primera canalización; continúa con los años del desarrollismo, que urbanizaron sus márgenes con el propósito de densificar un espacio marginal para el plano; y culmina con la conversión paulatina de los paseos de sus dos orillas en vía rápida, pieza de cierre de la M-30 en el decenio de 1980

Water seepage beneath dams on soluble evaporite deposits: a laboratory and field study (Caspe Dam, Spain)

The paper presents analytical methods and results for assessing the variation in the concentration of sulphate (and other ions) over space and time in groundwater flowing through a soluble evaporite terrain beneath a dam. The influence of effective porosity, groundwater flow velocity and the specific rate of dissolution (K′) are considered. The theoretical analysis was tested in a scale model simulating a dam constructed on heavily karstified bedrock. A simple and useful method for assessing how much material is lost through dissolution and how the rate of dissolution changes over time is considered in the context of the Caspe Dam, Spain.

Dinámica fluvial, propiedad de la tierra y conservación del paisaje aluvial en el entorno de Aranjuez(Madrid, Toledo)

El paisaje actual de la vega del Tajo es el resultado del efecto de la desamortización civil sobre el extenso territorio que integraba hasta la segunda mitad del siglo XIX el Real Sitio y Bosque de Aranjuez. También es fruto de la alteración del sistema fluvial producida por la regulación de la cabecera de la cuenca del Tajo con posterioridad a 1950. La incidencia del proceso desamortizador y de la regulación de la cuenca ha tenido una influencia temporal y espacial diferente. En una primera fase hasta 1880, la venta de bienes afectó mayoritariamente a las tierras situadas aguas abajo de la confluencia Tajo-Jarama y provocó la pérdida de muchos espacios forestales hasta entonces de uso eminentemente cinegético. Posteriormente, las aún extensas zonas naturales de la llanura de inundación en esta área, integradas en grandes fincas privadas surgidas tras la desamortización, se mantuvieron hasta finales de la década de 1960 debido a su frecuente inundación. A partir de esa fecha, la regulación de la cuenca permitió la ampliación de la frontera agrícola sobre las zonas más inestables, ocupadas hasta entonces por grandes sotos y praderas. En la actualidad, los espacios forestados más extensos se sitúan aguas arriba de la desembocadura del Jarama, protegidos por su localización en grandes propiedades públicas.

Güímar and La Orotava mega-landslides (Tenerife) and tsunamis deposits in Canary Islands

More than 20 mega-landslides have been described in the Canary Islands affecting the flanks of the volcanic edifices. Gliimar and La Orotava landslides, in Tenerife, are two exceptional cases due to their huge dimensions and outstanding geomorphological features. The estimated volume of these landslides exceed tens of cubic km. Tsunami deposits have been also identified in some of the islands of the archipelago probably associated to the large landslides of the islands flanks. An investigation has been carried out to explain the causes of these large instability processes and their failure mechanisms. One of the main aspects investigated was the geomechanical characteristics of the volcanic rock masses, specially the hyaloclastite rocks forming the substratum underlying the emerged volcanic building. The low strength and high deformability properties of these rocks have played a fundamental role on the stability of the island flanks. The results have shown the gravitational origin of these instability processes as the main failure mechanism. Volcanic eruptions or large earthquakes could be contributing factors to the instability, but according with the data obtained in Gliimar and La Orotava cases they are not necessary as triggering factors. As a result of the field work carried out in the frame of the project, three large tsunami deposits have been identified in the islands of Lanzarote, Tenerifc and Gran Canaria attributed to rnega-Iandslides, possibly related to Guimar and La Orotava. A Sumrnary of their main features is described.