1,900 research outputs found
Fluid mixing and thermal regimes beneath the PACMANUS hydrothermal field, Papua New Guinea: Helium and oxygen isotope data
No full textFluid mixing processes and thermal regimes within the Snowcap and Roman Ruins vent sites of the PACMANUS hydrothermal system, Papua New Guinea, were investigated using 3He/4He ratios from fluid inclusions within pyrite and anhydrite and the ?18O signature of anhydrite. Depressed 3He/4He ratios of 0.2–6.91RA appear to be caused by significant atmospheric diffusive exchange, whilst He–Ne diffusive fractionation precludes correction using 20Ne. 40Ar/36Ar ratios of 295–310 are elevated above seawater, indicating the majority of argon is seawater derived but with a magmatic component. ?18O anhydrite ratios are 6.5‰ to 11‰ for Snowcap and 6.4‰ to 11.9‰ for Roman Ruins. Using oxygen isotope fractionation factors for the anhydrite–water system, the temperatures calculated assuming isotopic equilibrium at depth are up to 100 °C cooler than fluid inclusion trapping temperatures. It is likely that anhydrite is precipitated rapidly, preventing ?18O equilibration. By comparing new ?18O values for anhydrite with corresponding published 87Sr/86Sr ratios, seawater is inferred to penetrate deep into the Snowcap system with little conductive heating. A simple fluid mixing model has been constructed whereby the differing venting styles can be explained by a plumbing system at depth which favors delivery of end-member hydrothermal fluid to the high temperature sites
Golden plumes: Substantial gold enrichment of oceanic crust during ridge-plume interaction
No full textMantle plume events are increasingly implicated as the source of gold (Au) in regions of the Earth that show a high Au endowment. However, the process of enriching oceanic crust in Au by plume activity is poorly understood and unconstrained. We present the first systematic study of Au concentrations in oceanic basalts as a function of distance from a plume center. We show that the influence of the Iceland plume on the Mid-Atlantic Ridge progressively enriches the oceanic crust in Au along the Reykjanes Ridge by as much as 13 times normal levels, over a distance of ?600 km, and that the enrichment can be attributed to specific plume components. This Au enrichment by the Iceland plume implies a genetic relationship between deep mantle upwelling and major gold mineralization
STRUCTURE OF THE ART-SPACE IN THE STORY "I" BY A.P. POTEMKIN
No full textThe author performs the analysis of the art space structure in A.P. Potemkin's story "I". Several interrelated spatial models are allocated and described: household space, natural space, social space, psychological space, transpersonal space
Pressure drop and turbulence statistics in transpired pipe flow
No full textMeasurements of turbulent flow in a horizontal pipe subjected to wall transpiration are presented. Results include data on global flow rates and pressure drop, and local mean and fluctuating velocity profiles. Two distinct flow transpiration rates are studied, = / = 0.0005 and 0.001. The effects of flow transpiration on the friction-coefficient are compared with theoretical predictions. The theory furnishes predictions accurate to 3\%
Fully Turbulent Mean Velocity Profile for Purely Viscous non-Newtonian Fluids
No full textThe characteristic near wall behavior of turbulent flow of purely-viscous non-Newtonian fluids is discussed for both power-law (P.-L.) and Herschel-Bulkley (H.-B.) rheological models. A proper scaling is presented for H.-B. fluids to establish an analogy with power-law fluids with same flow index. To provide reference data for turbulent flow of non-Newtonian fluids, DNS simulations of power-law fluids are conducted in a rectangular channel for a large range of power-law indices ( = 0.5, 0.69, 0.75, 0.9, 1, 1.2). The DNS data show that the mean velocity profile in the viscous and logarithmic layers follow expressions of the form and respectively, where shows a logarithmic dependency on the flow index.Comparison with some experimental data shows the above formulation to be valid for Reynolds numbers (based on shear velocity) as high as 1000
Author Correction: New perspectives on Neanderthal dispersal and turnover from Stajnia Cave (Poland)
No full textThe Author contributions section now reads:“W.N., A.N. and S.T. designed research; A.P., M.H., W.N., S.B., M.U., A.M., H.F., M.D.B., P.S., K.S., M.Ż., A.W., A.N. and S.T. performed research; A.P., M.H., W.N., S.B., M.U., A.M., H.F., M.D.B., P.S., K.S., M.Ż., A.W., A.N. and S.T. analysed data; A.P., M.H., S.T., W.N. and S.B. wrote the paper with the collaboration of all the co-authors.
Author Correction:A 41,500 year-old decorated ivory pendant from Stajnia Cave (Poland)
No full textCorrection to: Scientific Reports https://doi.org/10.1038/s41598-021-01221-6, published online 25 November 2021The original version of this Article contained errors in the author list where Marjolein D. Bosch was omitted from the author list, and Mikołaj Urbanowski was incorrectly listed as an author of the original Article, and has subsequently been removed.The Author contributions section now reads:“S.T. W.N. and A.N. conceived the project; S.T., W.N., A.P., M.B., S.C., M.D., H.F., A.M., M.D. B., D.P., M.P.R., C.M.R., V.S-M., G.M.S., P.S., M.S., K.S., A.V., F.W., H.W., A.W., M.Z., S.B., A.N., J-J. H., performed research; S.T., A.P., W.N., M.B., M.D.B., S.C., M.D., H.F., A.M., D.P., M.P.R., C.M.R., V.S-M., G.M.S., P.S., M.S., K.S., A.V., F.W., H.W., A.W., M.Z., S.B., A.N., J-J. H. analysed all archaeological data; S.T. and A.P. wrote the paper with the collaboration of all the co-authors.”The original Article and its accompanying Supplementary Information file have been corrected
Material Culture of the Volga Bolgars in the Scientific Works by A.P. Smirnov
No full textThe article considers the study of the scientific heritage of the outstanding Soviet archaeologist Aleksei Petrovich Smirnov, the founder of the scientific direction in the archaeology of the Volga-Kama region – Bulgaristics. Of particular interest are the scientific works of the researcher, which have become classic: "The Volga Bolgars" and "Essays on the ancient and medieval history of the peoples in the Middle Volga and the Kama regions" published in 1951 and 1952 respectively. In the first book, the author gives a detailed description not only of the social, economic and political events in the history of Volga Bolgaria within the formation approach, but also of the material culture of its population. The peculiarity of this part of A.P. Smirnov's research is that there is no typological classification here, although A.P. Smirnov uses its basic principles very often. The author claims that this was the result of the "Marxisation" of archaeological science carried out in the USSR in the 1930s, when the typological method was considered bourgeois and unsuitable for the Soviet history of material culture, as archaeology came to be called. A.P. Smirnov, well-versed in the typological method developed by his teacher V.A. Gorodtsov, deliberately limited its use. At the same time, he successfully applied the results of studies in the 1920s by his colleagues-archaeologists – A.V. Artsikhovsky, S.V. Kiselyov, V.V. Golmsten, and others, concerning the general analysis of the subject world in the context of social history. Smirnov, in the book "The Volga Bolgars", laid the foundations for further scientific developments of his students in the field of Bulgaristics, for example, T.A. Khlebnikova. These approaches were presented in A.P. Smirnov’s second work
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