The clustering of K∼20 galaxies in 17 radio galaxy fields

We investigate the angular correlation function, ο(θ), of the galaxies detected in the 2.1-μm K ' band in 17 fields (101.5 arcmin² in total), each containing a z ∼1.1 radio galaxy. There is a significant detection of galaxy clustering at a limit of K ∼20, with a ο(θ) amplitude similar to that estimated by Carlberg et al. at K =21.5. The ο(θ) amplitudes of these K -limited samples are higher than expected from the faint galaxy clustering in the blue and red passbands, but consistent with a pure luminosity evolution model if clustering is stable (ε=0) and the correlation function of early-type galaxies is steeper than that of spirals.
We do not detect a significant cross-correlation between the radio galaxies and the other galaxies in these fields. The upper limits on the cross-correlation are consistent with a mean clustering environment of Abell class 0 for z ∼1.1 radio galaxies, similar to that observed for radio galaxies at z ∼0.5, but would argue against an Abell class 1 or richer environment. As Abell 0 clustering around the radio galaxies would not significantly increase the ο(θ) amplitude of galaxies in these fields, stable clustering with a steep ξ( r ) for E/S0 galaxies appears to remain the most likely interpretation of the ο(θ) amplitude.
At K ≤20, the number of galaxy–galaxy pairs of 2–3 arcsec separation exceeds the random expectation by a factor of 2.15±0.26. The excess of close pairs is comparable to that previously reported for R -band data, and consistent with a ∼(1+ z )² evolution of the galaxy merger rate.     

The Visible Solar Spectral Irradiance from 350 to 850 nm As Measured by the SOLSPEC Spectrometer During the ATLAS I Mission

The SOLSPEC instrument has been built to carry out solar spectral irradiance measurements from 200 to 3000 nm. It consists of three spectrometers designed to measure the solar spectral irradiance in ultraviolet, visible, and infrared domains. It flew with the ATLAS I mission in March 1992. This paper is dedicated to the visible part of the solar spectrum. Comparisons with recent data are shown and differences below 450 nm are discussed.     

Sur l'existence de plusieurs facies geochimiques dans les schistes paleozoiques des pyrenees luchonnaises

Résumé Des formations paléozoïques d'origine essentiellement détritique, métamorphisées à des degrés divers (quartzophyllades, phyllades, micaschistes souvent feldspathiques à biotite, staurotide, andalousite, sillimamte) ont été échantillonnées méthodiquement dans les Pyrénées luchonnaises, à l'occasion de l'étude des relations structurales et géochimiques entre les formations granitiques du Massif du Lys-Caillaouas et leur environnement.La réalisation de 900 analyses (éléments majeurs) de ces « schistes » au sens large, prelevés le long de coupes systématiques à travers les principales unités régionales, pose avec acuité le problème d'une typologie chimique accordée aux connaissances sur la minéralogie des sédiments détritiques et sur leurs milieux de genèse.L'auteur tente en conséquence de présenter l'ensemble de ces analyses sous une forme qui mette en lumière quelques caractères importants de la sédimentation. Il propose à cet effet l'usage de deux diagrammes triangulaires dont l'un est destiné principalement à une présentation globale de la roche tandis que l'autre s'attache particulièrement aux silico-aluminates considérés comme la fraction la plus significative.Les différenciations que cette méthode de présentation fait apparaitre dans les séries échantillonnées, du Cambro-Ordovicien au Carbonifère inférieur, sont ensuite confrontées avec les connaissances classiques sur ce domaine pyrénéen. Au total, ce sont quelques uns des problèmes posés par l'utilisation de la géochimie dans des séries pélitiques fréquemment réputées monotones qui se trouvent évoqués sur un exemple assez large dont l'étude se poursuit.

---

Paleozoic formations of mainly detrital origin, which are metamorphized to various extents (quartzophyllades, phyllades, micaschists frequently containing feldspar, biotite, staurotide, andalousite, sillimanite) have been systematically sampled in the Luchon Pyrenees. This opportunity was offered by a study devoted to the relationship between the granitic formations of the Lys-Caillaouas massive and its environment.Over 900 of these « schists » taken on systematic profiles cross-cutting the principal regional units have been analyzed for major elements. This leads to the difficult problem of a chemical characterization of the mineralogical knowledge of detrital sediments and their medium of genesis.An attempt is made to restitute the mass of these analyses in a way that might throw light on some particularly important aspects of sedimentation. With this aim, two triangular diagrams are proposed. The first gives a global representation of the rock, whereas the second is concerned with silico-aluminates considered as the most significant fraction.The differenciations which appear in this graphical method, in the studied series proceeding from Cambro-Ordovicien up to the Carboniferous, are then compared with the classical knowledge of this part of the Pyrenees.Briefly, these are some of the problems which arise from the application of geochemistry to pelitic series, often considered monotonous. And these problems are treated on a broad example, the study of which is still being pursued.

---

Zusammenfassung Anläßlich umfassender, struktureller und geochemischer Untersuchungen in dem Granitmassiv des Lys-Caillaouas und seiner Umgebung wurden systematische Probenahmen in den Pyrenäen bei Luchon auch an diesen überwiegend detritischen Gesteinen durchgeführt. Sie liegen heute in verschiedenen Graden der Metamorphose vor. Quarzphyllite, Glimmerschiefer - oft mit Feldspat und Biotit, Andalusit und Sillimanit.900 Analysen des Makrochemismus dieser schiefrigen Gesteine erlauben systematische Profile durch die wichtigsten regionalen Einheiten zu geben. Es stellt sich das Problem, eine chemische Typologie zu finden, die sich in Übereinstimmung mit unseren Kenntnissen der Mineralogie detritischer Gesteine und ihrer Sedimentationsräume befindet.Verfasser versucht, die Gesamtheit dieser Analysen in Form eines Systems zu geben, das es gestattet, die wichtigsten Charakteristika der Sedimentation zu erfassen. Zu diesem Zweck werden zwei Dreiecks-Darstellungen vorgeschlagen, von denen die erste hauptsächlich dazu bestimmt ist, eine globale Darstellung des Gesteinschemismus zu geben. Das zweite Diagramm gibt vor allem eine Darstellung der Alumino-Silikate, die als charakteristische Fraktion dieser Gesteine anzusehen sind.Die Differenzierungen, die diese Methode in den Probenreihen vom Cambro-Ordoviz bis zum Karbon sichtbar werden läßt, verden anschließend verglichen mit den älteren, geologischen Kenntnissen dieses Abschnitts der Pyrenäen.Im Rahmen einer umfangreichen Arbeit, die noch fortgesetzt wird, sind dies einige Teilergebnisse, die den Wert geochemischer Untersuchungen gerade in pelitischen Serien zeigen, die gemeinhin als äußerst monoton gelten.

---

. .

     

Determination of predevelopment denudation rates of an agricultural watershed (Cayaguás River, Puerto Rico) using in-situ-produced Be in river-borne quartz

Accurate estimates of watershed denudation absent anthropogenic effects are required to develop strategies for mitigating accelerated physical erosion resulting from human activities, to model global geochemical cycles, and to examine interactions among climate, weathering, and uplift. We present a simple approach to estimate predevelopment denudation rates using in-situ-produced cosmogenic ¹⁰Be in fluvial sediments. Denudation processes in an agricultural watershed (Cayaguás River Basin, Puerto Rico) and a matched undisturbed watershed (Icacos River Basin) were compared using ¹⁰Be concentrations in quartz for various size fractions of bed material. The coarse fractions in both watersheds bear the imprint of long subsurface residence times. Fine material from old shallow soils contributes little, however, to the present-day sediment output of the Cayaguás. This confirms the recent and presumably anthropogenic origin of the modern high denudation rate in the Cayaguás Basin and suggests that pre-agricultural erosional conditions were comparable to those of the present-day Icacos.     

Multimodel analysis on the response of the AMOC under an increase of radiative forcing and its symmetrical reversal

Climate Dynamics - The response of the Atlantic meridional overturning circulation (AMOC) to an increase of radiative forcing (ramp-up) and a subsequent reversal of radiative forcing (ramp-down) is...     

Establishing constraints on groundwater ages with Cl,C, H,and noble gases: A case study in the eastern Paris basin,France

Groundwaters from the Tithonian/Kimmeridgian, Oxfordian and Upper Dogger aquifers, within the eastern part of the Paris basin (France), were characterised using ³H, ¹⁴C and ³⁶Cl, and noble gases tracers, to evaluate their residence times and determine their recharge period. This information is an important prerequisite to evaluating the confinement properties of the Callovo-Oxfordian clay formation sandwiched between the Oxfordian aquifer and the Dogger aquifer, currently being investigated by the French nuclear waste management agency (Andra) for radioactive waste disposal. Data presented in this paper are used to test 4 hypotheses.