Geophysical Study of the Valle Fértil Lineament Between 28°45′S and 31°30′S: Boundary Between the Cuyania and Pampia Terranes     

Antonio Introcaso  Myriam P. Martínez  Mario E. Gimnez  Francisco Ruiz 《Gondwana Research》2004,7(4):1117-1132

A gravimetric and magnetometric study was carried out in the north-eastern portion of the Cuyania terrane and adjacent Pampia terrane. Gravimetric models permitted to interpret the occurrence of dense materials at the suture zone between the latter terranes. Magnetometric models led to propose the existence of different susceptibilities on either side of the suture. The Curie temperature point depth, representing the lower boundary of the magnetised crust, was found to be located at 25 km, consistent with the lower limit of the brittle crust delineated by seismic data; this unusually thick portion of the crust is thought to release stress producing significant seismicity.

Moho depths determined from seismic studies near western Sierras Pampeanas are significantly greater than those obtained from gravimetric crustal models.

Considering mass and gravity changes originated by the flat-slab Nazca plate along Cuyania and western Pampia terranes, it is possible to reconcile Moho thickness obtained either by seismic or by gravity data. Thus, topography and crustal thickness are controlled not only by erosion and shortening but by upper mantle heterogeneities produced by: (a) the oceanic subducted Nazca plate with “normal slope” also including asthenospheric materials between both continental and oceanic lithospheres; (b) flat-slab subducted Nazca plate (as shown in this work) without significant asthenospheric materials between both lithospheres. These changes influence the relationship between topographic altitudes and crustal thickness in different ways, differing from the simple Airy system relationship and modifying the crustal scale shortening calculation. These changes are significantly enlarged in the study area. Future changes in Nazca Plate slope will produce changes in the isostatic balance.  相似文献   

Groundwater pollution in Quaternary aquifer of Vitoria – Gasteiz (Basque Country, Spain)     

I. Arrate  J. M. Sanchez-Perez  I. Antiguedad  M. A. Vallecillo  V. Iribar  M. Ruiz 《Environmental Geology》1997,30(3-4):257-265

 As a result of diverse changes in land use and in water-resource management in the high basin of the Zadorra River (Basque Country), an important loss of water resources and an intense contamination by nitrogen compounds has taken place. The purpose of this paper is to detail the land transformations that have taken place on the aquifer since the 1950s: increase of drainage network, change from dry to irrigated farming, and diversion of rivers at the aquifer unit inlet. Furthermore, we analyze the impact of these transformations on the hydrodynamics and water quality of this aquifer system. Received: 12 January 1996 · Accepted: 10 March 1996  相似文献   

Constraints on the nuclear emission of the Circinus galaxy: the torus     

M. Ruiz  A. Efstathiou  D.M. Alexander  J. Hough 《Monthly notices of the Royal Astronomical Society》2001,325(3):995-1001

In the context of the unified model of Seyfert galaxies, we use observations from the literature and a radiative transfer model to investigate the near-IR to mm emission produced by the presumed torus in the Circinus galaxy, from 2 μm to 1.3 mm. From the infrared SED modelling, we find that the total luminosity ( L _IR) in this wavelength range consists of similar contributions from the torus and starburst with a ratio of nuclear luminosity to starburst luminosity ( L _NUC/ L _SB)∼0.8 .
By using a similar torus model to that of NGC 1068, but without the conical dust , we find an upper limit to the outer torus radius of ∼12 pc with a best fit of ∼2 pc. The upper limit torus size estimated from the radiative transfer modelling is consistent with the 16-pc torus radius estimated from near-IR imaging polarimetry of Circinus.  相似文献   

Immobilization of toxic elements in mine residues derived from mining activities in the Iberian Pyrite Belt (SW Spain): Laboratory experiments     

Rafael Pérez-López  José Miguel NietoGabriel Ruiz de Almodóvar 《Applied Geochemistry》2007

In the mining environments of the Iberian Pyrite Belt (IPB), the oxidation of sulphide wastes generates acid drainage with high concentrations of SO₄, metals and metalloids (Acid Mine Drainage, AMD). These acid and extremely contaminated discharges are drained by the fluvial courses of the Huelva province (SW Spain) which deliver high concentrations of potentially toxic elements into the Gulf of Cádiz. In this work, the oxidation process of mine tailings in the IPB, the generation of AMD and the potential use of coal combustion fly ash as a possible alkaline treatment for neutralization of and metal removal from AMD, was studied in non-saturated column experiments. The laboratory column tests were conducted on a mine residue (71.6 wt% pyrite) with artificial rainfall or irrigation. A non-saturated column filled solely with the pyrite residue leached solutions with an acid pH (approx. 2) and high concentrations of SO₄ and metals. These leachates have the same composition as typical AMD, and the oxidation process can be compared with the natural oxidation of mine tailings in the IPB. However, the application of fly ash to the same amount of mine residue in another two non-saturated columns significantly increased the pH and decreased the SO₄ and metal concentrations in the leaching solutions. The improvement in the quality of leachates by fly ash addition in the laboratory was so effective that the leachate reached the pre-potability requirements of water for human consumption under EU regulations. The extrapolation of these experiments to the field is a promising solution for the decontamination of the fluvial courses of the IPB, and therefore, the decrease of pollutant loads discharging to the Gulf of Cádiz.  相似文献   

On the origin of variations in the composition of granitic rocks of Chile and Bolivia     

Andrew B. Vistelius  Carlos Ruiz Fuller 《Mathematical Geology》1969,1(1):113-114

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Possible detection of an old bipolar shell associated with η Carinae     

Joaquín Bohigas  Mauricio Tapia  María Teresa Ruiz †  Miguel Roth 《Monthly notices of the Royal Astronomical Society》2000,312(2):295-300

Continuum-subtracted dereddened images in the light of several atomic lines show the presence of an extended bipolar nebula surrounding η Carinae with size ∼100×45 arcsec² (1.3×0.5 pc²). This feature is best delineated in [O  iii ] 5007. The geometrical disposition and mass of the shell suggest that it was formed by mass ejections from η Carinae. The dynamic age of the nebula is ∼13 000/ V ₇ yr, where V ₇ is the mean expansion velocity in 100 km s⁻¹, and its mass is between 5 and 10 M_⊙. The nebula is photoionized and composed of unprocessed material. The major axes of the nebula and of the Homunculus are nearly perpendicular. We also report the discovery of elongated emission knots prominent in [N  ii ] located 64 to 100 arcsec away from η Carinae, which implies that they were ejected either centuries ago or at a more recent date but with extremely large velocities.  相似文献   

A near-infrared polarized bipolar cone in the Circinus galaxy     

M. Ruiz  D. M. Alexander  S. Young  J. Hough  S. L. Lumsden  C. A. Heisler † 《Monthly notices of the Royal Astronomical Society》2000,316(1):49-57

We present near-infrared broad-band polarization images of the nuclear regions of the Circinus galaxy in the J , H and K bands. For the first time the south-eastern reflection cone is detected in polarized light, which is obscured at optical wavelengths behind the galactic disc. This biconical structure is clearly observed in J - and H -band polarized flux, whilst in the K band a more compact structure is detected. Total flux J − K and H − K colour maps reveal a complex colour gradient toward the south-east direction (where the Circinus galactic disc is nearer to us). We find enhanced extinction in an arc-shaped structure, at about 200 pc from the nucleus, probably part of the star formation ring.
We model the polarized flux images with the scattering and torus model of Young et al., with the same basic input parameters as used by Alexander et al. in the spectropolarimetry modelling of Circinus. The best fit to the polarized flux is achieved with a torus radius of ∼16 pc, and a visual extinction A _V , through the torus, to the near-infrared emission regions of >66 mag.  相似文献   

The effects of deformation inertia (kinetic energy) in the orbital and spin evolution of close-in bodies     

A. C. M. Correia  C. Ragazzo  L. S. Ruiz 《Celestial Mechanics and Dynamical Astronomy》2018,130(8):51

The purpose of this work is to evaluate the effect of deformation inertia on tide dynamics, particularly within the context of the tide response equations proposed independently by Boué et al. (Celest Mech Dyn Astron 126:31–60, 2016) and Ragazzo and Ruiz (Celest Mech Dyn Astron 128(1):19–59, 2017). The singular limit as the inertia tends to zero is analyzed, and equations for the small inertia regime are proposed. The analysis of Love numbers shows that, independently of the rheology, deformation inertia can be neglected if the tide-forcing frequency is much smaller than the frequency of small oscillations of an ideal body made of a perfect (inviscid) fluid with the same inertial and gravitational properties of the original body. Finally, numerical integration of the full set of equations, which couples tide, spin and orbit, is used to evaluate the effect of inertia on the overall motion. The results are consistent with those obtained from the Love number analysis. The conclusion is that, from the point of view of orbital evolution of celestial bodies, deformation inertia can be safely neglected. (Exceptions may occur when a higher-order harmonic of the tide forcing has a high amplitude.)  相似文献   

The Multiscale TROPIcal CatchmentS critical zone observatory M-TROPICS dataset III: Hydro-geochemical monitoring of the Mule Hole catchment,south India     

Jean Riotte  Laurent Ruiz  Stéphane Audry  Benjamin Baud  Jean-Pierre Bedimo Bedimo  Laurie Boithias  Jean-Jacques Braun  Bernard Dupré  Jean-Louis Duprey  Mikael Faucheux  Christelle Lagane  Jean-Christophe Marechal  Hemanth Moger  Mandalagiri Subbarayappa Mohan Kumar  Harshad Parate  Olivier Ribolzi  Emma Rochelle-Newall  Buvaneshwari Sriramulu  Murari Varma  Muddu Sekhar 《水文研究》2021,35(5):e14196

Despite the importance of tropical ecosystems for climate regulation, biodiversity, water and nutrient cycles, only a few Critical Zone Observatories (CZOs) are located in the tropics. Among these, most are in humid climates, while very few data exist for semi-arid and sub-humid climates, due to the difficulty of estimating hydro-geochemical balances in catchments with ephemeral streams. We contribute to fill this gap by presenting a meteorological and hydro-geochemical dataset acquired at the Mule Hole catchment (4.1 km²), a pristine dry deciduous forest located in a biosphere reserve in south India. The dataset consists of time series of variables related to (i) meteorology, including rainfall, air temperature, relative humidity, wind speed and direction, and global radiation, (ii) hydrology, including water level and discharge at the catchment outlet, (iii) hydrogeology, including manual (monthly) and/or automated (from 15 min to hourly) groundwater levels in nine piezometers and (iv) geochemistry, including suspended sediment content in the stream and chemical composition of rainfall (event based), groundwater (monthly sampling) and stream water (storm events, 15 min to hourly frequency with an automatic sampler). The time series extend from 2003 to 2019. Measurement errors are minimized by frequent calibration of sensors and quality checks, both in the field and in the laboratory. Despite these precautions, several data gaps exist, due to occasional access restriction to the site and instrument destruction by wildlife. Results show that large seasonal and interannual variations of climatic conditions were reflected in the large variations of stream flow and groundwater recharge, as well as in water chemical composition. Notably, they reveal a long-term evolution of groundwater storage, suggesting hydrogeological cycles on a decadal scale. This dataset, alone or in combination with other data, has already allowed to better understand water and element cycling in tropical dry forests, and the role of forest diversity on biogeochemical cycles. As tropical ecosystems are underrepresented by Critical Zone Observatories, we expect this data note to be valuable for the global scientific community.  相似文献   

NH4-bearing micas in poly-metamorphic Alpuj��rride micaschists and gneisses from the central zone of the Betic Cordillera (Spain): tectono-metamorphic and crystal-chemical constraints     

Maria Dolores Ruiz Cruz 《Mineralogy and Petrology》2011,101(3-4):225-244

The content and distribution of NH₄-bearing micas in micaschists and paragneisses of the Alpujárride complex (Betic Cordillera, Spain) are interpreted on the basis of textures, metamorphic history and crystal-chemical constraints. NH₄ is present in important amounts in early micas, recording their older diagenetic-to-metamorphic history. NH₄ was inherited by micas formed in successive metamorphic events. At similar metamorphic grade, annite is enriched in NH₄ relative to muscovite with a fractionation of 4:1. Maximum NH₄ contents were estimated in golden annite from medium-grade schists and in retrogressive annite-chlorite mixed-layers (~1.0?wt.%). A Ti-NH₄ avoidance gives rise to associated chemical changes, such as the enrichment in Mg and in ^VIAl. These data suggest that NH₄ can be a decisive factor in chemical equilibrium and element partitioning between coexisting phases, thus affecting to the commonly used thermobarometers. Estimation of the P-T conditions from texturally different muscovite-annite pairs reveals the superposition of several stages of mica growth, under different geothermal gradients.  相似文献