Search results for " petrology"
showing 10 items of 1353 documents
Zircon M257 - a homogeneous natural reference material for the ion microprobe U-Pb analysis of zircon
2008
We introduce and propose zircon M257 as a future reference material for the determination of zircon U-Pb ages by means of secondary ion mass spectrometry. This light brownish, flawless, cut gemstone specimen from Sri Lanka weighed 5.14 g (25.7 carats). Zircon M257 has TIMS-determined, mean isotopic ratios (2s uncertainties) of 0.09100 ± 0.00003 for 206pb/238U and 0.7392 ± 0.0003 for 207pb/235U. Its 206pb/238U age is 561.3 ± 0.3 Ma (unweighted mean, uncertainty quoted at the 95% confidence level); the U-Pb system is concordant within uncertainty of decay constants. Zircon M257 contains ∼ 840 μg g−1 U (Th/U ∼ 0.27). The material exhibits remarkably low heterogeneity, with a virtual absence of…
Sky radiation, polarization and twilight radiation in Greenland
1966
A) The measurements of the spectral radiances in the solar almucantar (scattering function) and the degree of polarization of the skylight in Greenland indicate the following: 1) The air near the surface of the ice cap of Northern Greenland is very pure. 2) The sky radiance however is different from the pure molecular (Rayleigh) atmosphere, the measured scattering function does not followRayleigh's law. 3) On the other hand the measured scattering functions cannot be explained satisfactoryly by scattering on the aerosols which have been measured near the surface. 4) Therefore the presence of a few particles per cm3 with radii in the range 0.10≤r≤1μ in heigher atmospheric layers has to be po…
Mathematical background of the Riga dynamo experiment
2013
The Riga dynamo experiment is a laboratory model of the natural process that is responsible for all environmental magnetic-fields which are generated without human interference. This applies to the field of the Earth, the Sun, stars, and even galaxies which are produced by intense motions of large volumes of good electro-conducting fluids. For our experiment, we use molten sodium – the best liquid electro-conductor available in the laboratory. Approximately 2 m3 of molten sodium are filled into a prolonged cylinder, at the top of which rotates a propeller powered by 200 kW from two motors. The cylinder is divided by thin coaxial inner walls into three parts: in the inner tube the propeller …
THEORETISGHE UNTERSUCHUNGEN UBER DEN EINFLUSS DER VERWITTERUNGSSCHICHT AUF DAS SPEKTRUM ELASTISCHER WELLEN IN DER REFLEXIONSSEISMIK
1957
The following assumptions are made in the mathematical treatment of the problem. Below a plane earth's surface there is a three-layered elastic medium the interfaces of which are parallel to the earth's surface. The uppermost layer represents the weathered layer in which the velocity of propagation of seismic waves increases linearly with depth. The two lower layers, the so-called intermediate layer and the substratum each have a constant velocity. The surface of the earth is acted on simultaneously by a normal pressure N in the form of a Heaviside pulse. The seismic wave thus generated is propagated through the elastic media. The aim of the investigation is to study the shape of the wave 1…
A method of evaluation of measured light intensities and degrees of polarization of a unit volume of turbid air
1965
In order to interpret scattered light measurements a comparison with theoretical values is necessary. It is demonstrated by means of an example the possibility to obtain a first view on the measurement results. From calculated values of various aerosol size distribution models as well as from measurements were computed: 1) the angular quotients of scattered light intensity (i.e., quotients of intensity at two scattering angles and the same wavelength) and 2) the wavelength quotients (i.e., quotients of intensity at two wavelengths and the same scattering angle). The comparison between measured and theoretical values informs us of the exponent of the aerosol size distribution and its boundar…
Time-domain-induced polarization: Full-decay forward modeling and 1D laterally constrained inversion of Cole-Cole parameters
2012
Time-domain-induced polarization has significantly broadenedits field of reference during the last decade, from mineralexploration to environmental geophysics, e.g., for clay and peatidentification and landfill characterization. Though, insufficientmodeling tools have hitherto limited the use of time-domaininducedpolarization for wider purposes. For these reasons, anew forward code and inversion algorithm have been developedusing the full-time decay of the induced polarization response,together with an accurate description of the transmitter waveformand of the receiver transfer function, to reconstruct thedistribution of the Cole-Cole parameters of the earth. The accuratemodeling of the tra…
Shoot accumulation of several trace elements in native plant species from contaminated soils in the Peruvian Andes
2012
Abstract Metal mining gives access to very important resources but contributes to severe and diverse environmental problems. Until recently, little has been known about the remediation of mining sites in Latin America using metallophytes. The present study was designed to identify and characterize spontaneously growing heavy metal tolerant plant species in the area around the polymetallic Carolina mine in Hualgayoc (Cajamarca, Peru). The aim was to find species that are potentially useful for phytoremediation. Plants and soils were sampled and analysed for concentrations of As, Fe, Mn, Pb, Zn and Ti. The Translocation Factor (TF) and the Bioaccumulation Factor (BF) were determined and used …
Efficient full decay inversion of MRS data with a stretched-exponential approximation of the distribution
2012
SUMMARY We present a new, efficient and accurate forward modelling and inversion scheme for magnetic resonance sounding (MRS) data. MRS, also called surface-nuclear magnetic resonance (surface-NMR), is the only non-invasive geophysical technique that directly detects free water in the subsurface. Based on the physical principle of NMR, protons of the water molecules in the subsurface are excited at a specific frequency, and the superposition of signals from all protons within the excited earth volume is measured to estimate the subsurface water content and other hydrological parameters. In this paper, a new inversion scheme is presented in which the entire data set is used, and multi-expone…
Environmental impact of magmatic fluorine emission in the Mt. Etna area
2007
-UniversitA degli Studi di Palermo, Italy -Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Palermo - Unione Europea, Fondo Sociale Europeo
Climate Sensitivity and Parameter Coherency in Annually Resolved δ13C and δ18O from Pinus uncinata Tree-Ring Data in the Spanish Pyrenees
2014
We explore the 20th century climate sensitivity of annually resolved carbon and oxygen isotope ratios in five Pinus uncinata individuals from the upper treeline in similar to 2400 m asl of the Span ...