Mass modelling of dwarf spheroidal galaxies: the effect of unbound stars from tidal tails and the Milky Way     

Jaros&#;aw Klimentowski  Ewa L. &#;okas  Stelios Kazantzidis  Francisco Prada  Lucio Mayer  Gary A. Mamon 《Monthly notices of the Royal Astronomical Society》2007,378(1):353-368

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Erratum to: High-Ti,bright-CL rims in volcanic quartz: a result of very rapid growth     

Ayla?S.?PamukcuEmail author  Mark?S.?Ghiorso  Guilherme?A.?R.?Gualda 《Contributions to Mineralogy and Petrology》2017,172(1):5

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The Serra da Graciosa A-type Granites and Syenites, southern Brazil. Part 3: Magmatic evolution and post-magmatic breakdown of amphiboles of the alkaline association     

Guilherme A.R. Gualda  Silvio R.F. Vlach 《Lithos》2007,93(3-4):328-339

Amphiboles are the main mafic minerals in most metaluminous to peralkaline alkali-feldspar granites and syenites, and they usually preserve an important record of the compositional evolution of the melts from which they crystallize. In the alkaline association of the Serra da Graciosa A-type Granites and Syenites (southern Brazil), amphibole compositions span a large range, including calcic, sodic–calcic, and sodic amphiboles. Calcic amphiboles are typically observed in the metaluminous rocks, while sodic amphiboles are characteristic of the more strongly peralkaline rocks; sodic–calcic amphiboles are found in intermediate varieties. Compositional variations record the differentiation trends within two petrographic series of the alkaline association. The overall evolution of amphibole compositions is similar in both: they reveal a progressive increase in Na and Fe³⁺ with differentiation (increase in alkalinity of the magmas), a characteristic shared by undersaturated peralkaline (or agpaitic) differentiation trends. In detail, however, the evolutions of the amphibole compositions in the two series are distinct. In Alkaline series 1, the cores of the crystals form a continuum from calcic to sodic compositions, with the exception of a small compositional gap within the sodic–calcic amphiboles. The rims, however, show compositions that diverge from this main trend; this divergence results from increasing amounts of the oxy-amphibole component, and reflects more oxidizing conditions at the final stages of magmatic crystallization. In Alkaline series 2, these oxidation trends are much more subtle and a reverse trend is observed in the sodic amphiboles. Sodic–calcic amphiboles are in several cases replaced by intergrowths of post-magmatic sodic amphibole and Al-poor (“tetrasilicic”) biotite.  相似文献   

The decline and recovery of a persistent Texas brown tide algal bloom in the Laguna Madre (Texas, USA)     

Edward J. Buskey  Hongbin Liu  Christopher Collumb  Jose Guilherme F. Bersano 《Estuaries and Coasts》2001,24(3):337-346

The Laguna Madre has experienced a persistent bloom ofAureoumbra lagunensis for over eight years. The persistence of this bloom may be due in part to the often hypersaline conditions in Laguna Madre (40–60 psu) that favor the growth ofA. lagunensis. Above-normal rainfall in the fall of 1997 reduced the salinities in Baffin Bay from >40 to<20 psu.A. lagunensis cell densities dropped from>10⁶ cells ml⁻¹ in July 1997 to c. 200 cells ml⁻¹ in January 1998. During this time of low brown tide density, phytoplankton biomass generally remained high and the Laguna Madre experienced successive blooms of diatoms (Rhizosolenia spp.) and cyanobacteria. Hypersaline conditions returned in 1998 and brown tide densities increased to>0.5 × 10⁶ cells ml⁻¹ by summer. The extraordinary persistence of the brown tide and the unusual sequence of intense blooms may be related in part to the reduction of zooplankton populations. Microzooplankton populations declined following the above-normal rain in the fall of 1997; populations did not recover until fall 1998. Copepod populations also declined sharply and remained low in Laguna Madre, but recovered by summer 1998 in Baffin Bay. Dilution experiments indicated that microzooplankton grazing and phytoplankton growth were usually balanced when measured during our cruises. The rapid recovery of theA. lagunensis bloom suggests that this alga may be a more resilient component of the Laguna Madre flora than previously suspected.  相似文献   

Comment on ‘Simultaneous vibroseis recording’ by J.E. Martin and C.W.M. Bacon1     

Lucio Deluchi 《Geophysical Prospecting》1994,42(5):521-521

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K-ar ages of the yemen plateau     

Lucia Civetta  Luigi La Volpe  Lucio Lirer 《Journal of Volcanology and Geothermal Research》1978,4(3-4)

The temporal evolution of the Yemen Trap series is examined in the light of K-Ar radiometric data.Rifting and volcanic activity characterize the Yemen plateau between 30 and 20 m.y. confirming a fairly common history of the Afro-Arabian plate on both sides of the Red Sea.  相似文献   

3D multivalued travel time and amplitude maps   总被引：2，自引：0，他引：2  

P. S. Lucio  G. Lambaré  A. Hanyga 《Pure and Applied Geophysics》1996,148(3-4):449-479

An algorithm for computing multivalued maps for travel time, amplitude and any other ray related variable in 3D smooth velocity models is presented. It is based on the construction of successive isochrons by tracing a uniformly dense discrete set of rays by fixed travel-time steps. Ray tracing is based on Hamiltonian formulation and includes computation of paraxial matrices. A ray density criterion ensures uniform ray density along isochrons over the entire ray field including caustics. Applications to complex models are shown.  相似文献   

Two-Dimensional Multivalued Traveltime and Amplitude Maps By Uniform Sampling of A Ray Field   总被引：8，自引：0，他引：8  

G. Lambará  P. S. Lucio  A. Hanyga 《Geophysical Journal International》1996,125(2):584-598

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Volcanic Risk Assessment and Mapping in the Vesuvian Area Using GIS   总被引：3，自引：0，他引：3  

Lirer  Lucio  Vitelli  Livia 《Natural Hazards》1998,17(1):1-15

This paper assesses the risk to people and property from lava flow hazard in the Vesuvian area of Italy using a Geographical Information System (GIS). The intense urbanisation and dense population near Mt. Vesuvius make the area very hazardous. Due to the large amount of available data, GIS is an essential tool to facilitate risk evaluation and constant monitoring of the zone. This analysis is based mainly on a lava flow hazard map of Mt. Vesuvius, determined from volcanic activity between 1631 and 1944. A land-use zonation map of the area was created in order to show areal distribution of the resources, built-up centres and population. For each of the 17 municipalities in the area, demographic and urban data were entered into the GIS database and linked to each appropriate geographic unit in order to create a set of reference maps at the 1:50 000 scale. The lava flow hazard map was overlain on the land use map, and spatial and numerical information of risk were extracted from the resulting maps.  相似文献   

Hydrology and Salt Balance in a Large, Hypersaline Coastal Lagoon: Lagoa de Araruama, Brazil     

Bjrn Kjerfve  Schettini C. A. F.  Bastiaan Knoppers  Guilherme Lessa  Ferreira H. O. 《Estuarine, Coastal and Shelf Science》1996,42(6):701-725

Lagoa de Araruama in the state of Rio de Janeiro, Brazil, is a hypersaline coastal lagoon as a result of semi-arid climate conditions, a small drainage basin and a choked entrance channel. The lagoon has been continuously hypersaline for at least 4·5 centuries, but the mean salinity has varied substantially. It has recently decreased from 57 to 52 as indicated by density (salinity) measurements between 1965 and 1990.Analysis of more than 20 years of salinity time series data, in addition to monthly lagoon cruises to measure the spatial salinity distribution, indicate that the lagoon salinity largely fluctuates in response to the difference between evaporation and precipitation. The major factor explaining the long-term trend of decreasing salinity in the lagoon is the constant pumping of 1 m³s⁻¹of freshwater to the communities surrounding the lagoon from an adjacent watershed, and subsequent discharge of this water into Lagoa de Araruama. The net salt budget is primarily a balance between the advective import of salt from the coastal ocean and eddy diffusive export of salt to the ocean, although the extensive mining of salt from the lagoon during past decades is also a small but significant contribution to the salt budget. The flushing half-life is proposed as a useful time scale of water exchange, is calculated based on a combination of hydrological and tidal processes, and is excellent for comparison of lagoons and assessing water quality changes. The flushing half-life measures 83·5 days for Lagoa de Araruama, considerably longer than for most other coastal lagoons. The proposed dredging of a second ocean channel to Lagoa de Araruama is probably not a good idea. It is likely to accelerate the decrease of lagoon salinity and somewhat improve the lagoon water exchange. At the same time, this will eliminate the apparent buffering capacity provided by the hypersaline environment, and thus may potentially cause water quality problems.  相似文献