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 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   

Molybdenite Mineralization and Re‐Os Geochronology of the Escondida and Escondida Norte Porphyry Deposits,Northern Chile     

Bárbara Romero  Shoji Kojima  Chilong Wong  Walter Véliz  Joaquin Ruiz 《Resource Geology》2011,61(1):91-100

Molybdenum is an economically important subproduct of North Chilean porphyry‐type deposits, and thus spatial and temporal distribution of molybdenite as the primary Mo‐bearing mineral in the Escondida and Escondida Norte deposits were characterized using several mineralogical and chemical techniques and the Re‐Os dating method. Molybdenum is distributed extensively in the two deposits, and high molybdenum concentrations (>500 ppm) are recognized particularly in the chlorite‐sericite transitional zone between the potassic and sericitic zones. Two modes of occurrence of molybdenite are observed in the Escondida deposit: aggregates with Cu‐Fe‐sulfide minerals in fine veinlets (sulfide‐veinlet type), and monomineralic microveinlets associated with NE‐trending faults. The former and the latter yielded ages of 36.1 ± 0.2 Ma and 35.2 ± 0.2 Ma, respectively. Re‐Os dating of Escondida Norte molybdenites also show two distinct episodes, at 37.7 ± 0.3 Ma and a younger episode at 36.6 ± 0.2 Ma. These data indicate that the Escondida Norte is older than the main Escondida deposit. The Re‐Os age data combined with those of the porphyry emplacement suggest that the molybdenite mineralization in the Escondida district occurred as several short episodic pulses during the late‐magmatic to hydrothermal transition, and that the Cu‐Mo deposits were formed in a variable overall period spanning 1 to 5 m.y.  相似文献   

Atmospheric-induced variability of hydrological and biogeochemical signatures in the NW Alboran Sea. Consequences for the spawning and nursery habitats of European anchovy     

D. Macías  I.A. CatalánJ. Solé  B. Morales-NinJ. Ruiz 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(12):1175-1188

The north-western Alboran Sea is a highly dynamic region in which the hydrological processes are mainly controlled by the entrance of the Atlantic Jet (AJ) through the Strait of Gibraltar. The biological patterns of the area are also related to this variability in which atmospheric pressure distributions and wind intensity and direction play major roles. In this work, we studied how changes in atmospheric forcing (from high atmospheric pressure over the Mediterranean to low atmospheric pressure) induced alterations in the physical and biogeochemical environment by re-activating coastal upwelling on the Spanish shore. The nursery area of European anchovy (Engraulis encrasicolus) in the NW Alboran Sea, confirmed to be the very coastal band around Malaga Bay, did not show any drastic change in its biogeochemical characteristics, indicating that this coastal region is somewhat isolated from the rest of the basin. Our data also suggests that anchovy distribution is tightly coupled to the presence of microzooplankton rather than mesozooplankton. Finally, we use detailed physical and biological information to evaluate a hydrological-biogeochemical coupled model with a specific hydrological configuration to represent the Alboran basin. This model is able to reproduce the general circulation patterns in the region forced by the AJ movements only including two variable external forcings; atmospheric pressure over the western Mediterranean and realistic wind fields.  相似文献   

Heat flow and depth to a possible internal ocean on Triton     

Javier Ruiz 《Icarus》2003,166(2):436-439

The Raz Fossae, a pair of ≈15-km wide trough en echelon interpreted as grabens, can be used to propose an estimation of the depth to the brittle-ductile transition on Triton. This estimation may in turn give an idea of the thermal state of Triton's icy lithosphere when these features formed. Given the young age of its surface, the conclusions obtained could be roughly applicable to the present state of this satellite of Neptune. Considering water or ammonia dihydrate as possible components of the lithosphere and a feasible range of strain rates, it was estimated that surface heat flow is greater than that inferred from radiogenic heating, especially for a lithosphere dominated by water. Also, an internal ocean could lie at a depth of only ∼20 km beneath the surface. The presence over the surface of an insulating layer of ice of low thermal conductivity (e.g., nitrogen) or of regolith would only substantially alter these estimates if the effective surface temperature were considerably higher than the observed value of 38 K.  相似文献   

Episodic flood inundations of the northern plains of Mars     

Alberto G. Fairén  James M. Dohm  Miguel A. de Pablo  Javier Ruiz  Robert C. Anderson 《Icarus》2003,165(1):53-67

Throughout the recorded history of Mars, liquid water has distinctly shaped its landscape, including the prominent circum-Chryse and the northwestern slope valleys outflow channel systems, and the extremely flat northern plains topography at the distal reaches of these outflow channel systems. Paleotopographic reconstructions of the Tharsis magmatic complex reveal the existence of an Europe-sized Noachian drainage basin and subsequent aquifer system in eastern Tharsis. This basin is proposed to have sourced outburst floodwaters that sculpted the outflow channels, and ponded to form various hypothesized oceans, seas, and lakes episodically through time. These floodwaters decreased in volume with time due to inadequate groundwater recharge of the Tharsis aquifer system. Martian topography, as observed from the Mars Orbiter Laser Altimeter, corresponds well to these ancient flood inundations, including the approximated shorelines that have been proposed for the northern plains. Stratigraphy, geomorphology, and topography record at least one great Noachian-Early Hesperian northern plains ocean, a Late Hesperian sea inset within the margin of the high water marks of the previous ocean, and a number of widely distributed minor lakes that may represent a reduced Late Hesperian sea, or ponded waters in the deepest reaches of the northern plains related to minor Tharsis- and Elysium-induced Amazonian flooding.  相似文献   

Asynchroneity of maximum glacier advances in the central Spanish Pyrenees     

Jos M. García‐Ruiz  Blas L. Valero‐Garcs  Carlos Martí‐Bono  Penlope Gonzlez‐Sampriz 《第四纪科学杂志》2003,18(1):61-72

The deglaciation history of the Escarra and Lana Mayor glaciers (Upper Gállego valley, central Spanish Pyrenees) had been reconstructed on the basis of detailed geomorphological studies of glacier deposits, sedimentological and palynological analyses of glacial lake sediments and an accelerator mass spectrometry (AMS) ¹⁴C chronology based on minimum ages from glacial lake deposits. The maximum extent of the Pyrenean glaciers during the last glaciation was before 30 000 yr BP and pre‐dated the maximum advances of the Scandinavian Ice Sheet and some Alpine glaciers. A later advance occurred during the coldest period (around 20 000 yr BP), synchronous with the maximum global ice extent, but in the Pyrenees it was less extensive than the previous one. Later, there were minor advances followed by a stage of debris‐covered glaciers and a phase of moraine formation near cirque backwalls. The deglaciation chronology of the Upper Gállego valley provides more examples of the general asynchroneity between mountain and continental glaciers. The asynchroneity of maximum advances may be explained by different regional responses to climatic forcing and by the southern latitude of the Pyrenees. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Estimation of Heat Sources in Planetary Crusts from Isotherm Depth,Surface Heat Flow,and Crustal Thickness     

Ruiz  Javier  Tejero  Rosa 《Earth, Moon, and Planets》2002,91(3):185-193

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Structural behaviour and design criteria of under‐deck cable‐stayed bridges subjected to seismic action     

Alfredo Camara  Ana M. Ruiz‐Teran  Peter J. Stafford 《地震工程与结构动力学》2013,42(6):891-912

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