LA COMPOSITION MINERALOGIQUE ET CHIMIQUE DES ROCHES ERUPTIVES ET PARTICULIEREMENT DES LAVES MESOZOIQUES ET PLUS RECENTES DE LA CHINE ORIENTALE Par A. Lacroix.

Au cours d'un voyage en Chine, effectue en decembre 1927, j'al eu I'honneur et le plaisir d'etre recu a Peking par la Societe geologique de Chine et d'etre ainsi le temoin de sa grande activite scientifique. Aussi, je tiens a lui offrir le resultat de l'etude mineralogique et chimique des roches que j'ai     

LES ROCHES ERUPTIVES POST-PALEOZOIQUES DU NORD DE LA CHINE

Les Ioches dont l'etude petrograpmque par M. Lacroix fait l'objet principal de la communication suivante, ont ete recueillies, soit par M. Lacroix lui-meme, soit par M. G. B. Barbour, soit surtout par nous-memes. (P. Teilhard     

The effect of light on the release of organic compounds by the cyanobacteriumOscillatoria rubescens

The effect of light intensity on the release of dissolved organic carbon during photosynthesis on NaH¹⁴CO₃ was investigated using the phytoplanktonic CyanobacteriumOscillatoria rubescens. The released products were fractionated by molecular size and chemical identifications attempted using combined thin-layer electrophoresis and chromatography, and high pressure liquid chromatography.Within the range of irradiances tested (from 6 to 60 µmole m^–2 sec^–1), though the upper one inhibited photosynthesis ofO. rubescens, light had little effect on the quantity and composition of the excreted products. The released carbon was always lower than 3% of the incorporated carbon, and mainly composed (62 to 86%) by small molecular weight compounds. The prevailing identified compounds were amino acids which represented more than 20% of the excreted carbon. Among organic acids, glycolic acid accounted for less than 2% of the recovered radioactivity. Glucose was the only identified sugar.Abbreviations EOC excreted organic carbon - DOC dissolved organic carbon - PER percent extracellular release - LMW low molecular weight - HMW high molecular weight - AA amino acids - µmoles m^–2 sec^–1 = µEinsteins m^–2 sec^–1     

Integrating variations in the soil chloride profile and evaporativity for in-situ estimation of evaporation in arid zones: an application in south-eastern Morocco

In arid regions, knowledge of the evaporation rate from the water table is essential for appropriate management of scarce resources and to prevent land degradation. Soil chloride profiles in the unsaturated zone of a bare soil in an arid area of south-eastern Morocco were used to assess the evaporation flux, using chloride inventories in conjunction with evaporative demand. Moisture fluxes were calculated from measured chloride concentrations on the basis of a steady-state flow model. The chloride profiles displayed large variations in concentrations and had (1) low chloride concentrations near the soil surface, (2) maximum chloride concentrations at depths of 11–14 cm beneath the soil surface, respectively in July and February, and (3) gradually decreasing chloride concentrations while depth increased below these peaks. Evaporative demands were found to be inversely proportional to the depth of evaporation fronts and proportional to evaporation fluxes. In addition, the evaporation along the profiles seems to be controlled by the soil composition and texture. The investigation of chloride profiles in February and July enabled the determination of a value for annual evaporation (～30 mm), which is in good agreement with the value estimated by the Allison-Barnes type model (～32 mm).     

Types de magma et minéralisations correspondantes dans le cas des roches Plutoniques

Zusammenfassung Nach einem kurzen Überblick zur Entwicklung der Vorstellungen werden die Beziehungen zwischen magmatischer Differentiation und Metallogenese untersucht. Es ist heute nicht möglich, genaue Korrelationen zwischen den Arten der Erzlagerstätten und den Stadien der klassischen differenzierten Serien magmatischer Gesteine aufzustellen wegen der Unsicherheiten bei der Differentiation der Plutonite. Immerhin gibt es solche Korrelationen aufgrund der Erfahrungen in vielen Lagerstätten der Erde.Des weiteren werden die natürlichen Hauptgruppen plutonischer Gesteine nach ihrer Metallogenese untersucht: kalkalkalische Granitoide, alkalische Gesteine, basisch orogene Intrusiva und Lopolithe, Ophiolite, ultrabasische Intrusiva im Basement.Schließlich wird die Frage der metallogenen Provinzen hinsichtlich der besonderen metallogenen Wirksamkeit der Magmen dieser Provinzen behandelt.

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After briefly recalling the evolution of ideas, the relations between magmatic differentiation and metallogeny are investigated. It is not possible today to settle accurate correlations between types of ore deposits and stages of the classical differentiated series of magmatic rocks, owing to uncertainties for the plutonites. Nevertheless such correlations do exist from experience of many deposits in the world.Then the principal natural groups of plutonic rocks are surveyed for metallogeny: calcalkalic granitoïdes, alkalic rocks, basic orogenic intrusives and Iopoliths, ophiolites, ultrabasic intrusives in basement rocks.Finally the problem of metallogenic provinces is outlined, concerning efficiency of their varied magmas to reconstitute deposits of the same metals, notwithstanding the peculiarities of these magmas.

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Résumé Après un bref rappel de l'évolution des idées, les rapports de la différenciation magmatique avec la métallogénie sont examinés. Il n'est pas possible actuellement de donner une corrélation précise entre les étapes des grandes lignées de différenciation et les types de minéralisation, à cause des indéterminations et des incertitudes de la différenciation des roches plutoniques. Cependant de telles corrélations sont indubitables, d'après l'expérience des gisements métallifères du monde entier.On examine ensuite la métallogénie des principaux groupes naturels de roches plutoniques: granitoïdes calco-alcalins, roches alcalines, intrusions basiques en zones orogéniques, lopolites, ophiolites, intrusions basiques des socles.Le problème des provinces métallogéniques est évoqué enfin, en ce qui concerne l'efficacité métallogénique spécifique des magmas de ces provinces.

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Concentrations en PCB et DDT des sédiments superficiels de la rive suisse du lac Léman

The PCB concentrations of sediments can be considered as high and risk to produce a long-term contamination of the lake ecosystem. The shoreline near Lausanne area is the most polluted. Those results show that pollution by DDT is decreasing.     

Colonisation d'une population d'Oscillatoria rubescens (Cyanophyceae) par une bacterie epiphyte

The presence of unknown bacteria upon filaments of the CyanophyteOscillatoria rubescens was observed in the Lake Leman (Lake of Geneva) during Autumn 1985. Conditions of this colonization and the morphology of the association are described. These bacteria probably belong to theCaulobacter group. To explain this colonization we suggest that bacteria respond chemotactically to Cyanophyte exudates.

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Colonisation d'une population d'Oscillatoria rubescens (Cyanophyceae) par une bacterie epiphyte

     

Résultats préliminaires d'études sur des méthodes de détermination de l'âge individuel par l'histologie chez quelques Téléostéens

The study discusses the potential of various histological methods for enhancing the readability of the lines of arrested growth (LAC, annuli) in different bony elements, particularly fin rays, of some freshwater fish species.      

Eutrophisation et faune benthique de trois lacs de montagne

Zoobenthic communities were used to indicate the trophic state of three mountain lakes of western Switzerland. In these lakes, the macrobenthos was constituted mainly by oligochaetes and chironomid larvae;Tubifex tubifex was the most abundant worm species. In Lakes Lioson and Hongrin, the abundance of zoobenthos did not change or increased slightly with depth andStylodrilus heringianus was present. In Lake Chavonnes, zoobenthos decreased strongly with depth and it consisted mainly ofTubifex tubifex. These data, compared with those from other oligotrophic lakes, indicated that Lake Chavonnes was eutrophic whereas Lakes Lioson and Hongrin were oligotrophic. However, Lake Hongrin—an artificial lake made in 1968—constituted a special case. Its water comes in part from mountain rivers and in part from Lake Geneva. Consequently, some benthic species of Lake Geneva have colonized Lake Hongrin and its water is warmer than in a typical mountain lake.      

Croissance et reproduction de l'omble-chevalier,Salvelinus alpinus (L.), dans le lac de Neuchâtel (Suisse)

The arctic char (Salvelinus alpinus) which has disappeared from Lake Neuchatel near 1963, has been reintroduced into this lake since 1979. In this study, growth and reproduction of char have been analyzed 4 years after reintroduction. Age determination based on scales were more reliable then those based on otoliths. Growth rate decreased from the cohort born in 1979 to the cohort born in 1982. Nevertheless growth of char in Lake Neuchatel is fast compared to other char populations. About 33% of the males were sexually mature in the second year of life. At this age, no females, and in the third year of life, only 18% of the females were mature. Most fish of both sex were mature at an age of 4 years. A high correlation was found for data taken from other authors between fecundity and length of char. The data from Lake Neuchatel char (this study) fit very well with this general relation.