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The Variscan granites from the Western Erzgebirge were repeatedly dated by various methods, but no consensus has been reached about their exact intrusion ages. This study presents a multi-dating approach for the four largest intrusions from the Western Erzgebirge (Aue-Schwarzenberg, Bergen, Eibenstock, Kirchberg). We analysed several samples from each pluton/suite with zircon U-Pb CA-ID-TIMS (chemical abrasion-isotope dilution-thermal ionization mass spectrometry) to obtain robust temporal information on their age and tempo of intrusion. These data enable us for the first time to define three intrusive episodes of 1-2 Ma each, separated by quiet periods of several Ma. The Aue-Schwarzenberg suite represents the oldest granites that intruded at similar to 323-322 Ma followed by the granites from Bergen and Kirchberg 2-4 Ma later. The highly evolved ore-bearing granites from the Eibenstock pluton intruded after a time lag of similar to 5 Ma at similar to 315-314 Ma. The new data show that there is a resolvable age difference between the two known granite groups. Granite group 2 (also assigned as younger igneous complex, represented by the Eibenstock pluton) is >= 5 Ma younger than granite group 1 (assigned as older igneous complex, represented by granites from Aue-Schwarzenberg, Bergen and Kirchberg). Protracted magmatism and late-/post-magmatic fluid flow partly reset the U-Pb system of these granites to variable degrees, making a precise and accurate dating of their intrusion ages challenging. Pb loss in zircons is often combined with high common Pb (Pb-c). SHRIMP/SIMS (sensitive high mass resolution ion microprobe/secondary ion mass spectrometry) and LA-ICP-MS (laser ablation-inductively coupled plasma-mass spectrometry) on non-CA zircons document that Pb loss and high Pb c is quite variable within zircon grains and may be located in micro-fractures. We demonstrate that chemical abrasion (CA) clearly minimizes or removes both Pb loss and Pb-c. Results from prior LA

The Saxothuringian Zone of the Variscan orogen is composed of autochthonous and allochthonous domains. Dating of metamorphic events in the domains of the Saxonian Granulite Massiv, and the Münchberg, Frankenberg, and Erzgebirge nappe units is critical for resolving the complex geodynamic evolution during the Variscan orogeny. The in-situ chemical Th-U-Pb monazite (Th, U, Si, LREE, Y, Ca)PO4 dating by electron probe microanalysis (EPMA) has demonstrated its high potential to resolve polyphase metamorphism. The method is based on the premise that monazite inherits negligible amounts of common Pb and that the radiogenic Pb is retained due to very low diffusion rates even at high T [1]. A monazite dating routine, enclosing the analysis of HREE, was performed with a JEOL-8530F, producing 100 - 200 single analyses per sample. Also, energy dispersive x-ray mapping (GXMAP) by automated SEM was used for semiquantitative identification of garnet zonation pattern. Quantitative chemical compositions of garnet and related plagioclase, biotite and muscovite were then measured by EPMA for geothermobarometric estimates by cation exchange and net transfer reactions. Monazite is abundant in lenses of granulitic garnet gneisses ("saidenbachites") in the central Erzgebirge UHP unit. The monazite ThO2*-PbO data straightly define isochrons at around 335±3 Ma. High pyrope (27 mol%) garnet crystallised at 830 °C/19 kbar [2]. Despite such high T, the monazite Y contents are low. In the intercalated MP micaschists, the monazite ThO2*-PbO isochrones appear more diverse, between 334±4 and 344±5 Ma. Furthermore, monazite has been studied in the micaschists and related phyllites of the western Erzgebirge. The monazite ThO2*-PbO data define isochrones between 323±10 and 360±10 Ma, with most samples around 340 Ma, interpreted as the ages of Variscan regional metamorphism. Several samples bear an older minor monazite population at ages between 415 to 432 Ma. Special regard has been dedicated to met

The Saxothuringian Zone of the Variscan orogen is composed of autochthonous and allochthonous domains. Dating of metamorphic events in the domains of the Saxonian Granulite Massiv, and the Münchberg, Frankenberg, and Erzgebirge nappe units is critical for resolving the complex geodynamic evolution during the Variscan orogeny. The in-situ chemical Th-U-Pb monazite (Th, U, Si, LREE, Y, Ca)PO4 dating by electron probe microanalysis (EPMA) has demonstrated its high potential to resolve polyphase metamorphism. The method is based on the premise that monazite inherits negligible amounts of common Pb and that the radiogenic Pb is retained due to very low diffusion rates even at high T [1]. A monazite dating routine, enclosing the analysis of HREE, was performed with a JEOL-8530F, producing 100 - 200 single analyses per sample. Also, energy dispersive x-ray mapping (GXMAP) by automated SEM was used for semiquantitative identification of garnet zonation pattern. Quantitative chemical compositions of garnet and related plagioclase, biotite and muscovite were then measured by EPMA for geothermobarometric estimates by cation exchange and net transfer reactions. Monazite is abundant in lenses of granulitic garnet gneisses ("saidenbachites") in the central Erzgebirge UHP unit. The monazite ThO2*-PbO data straightly define isochrons at around 335±3 Ma. High pyrope (27 mol%) garnet crystallised at 830 °C/19 kbar [2]. Despite such high T, the monazite Y contents are low. In the intercalated MP micaschists, the monazite ThO2*-PbO isochrones appear more diverse, between 334±4 and 344±5 Ma. Furthermore, monazite has been studied in the micaschists and related phyllites of the western Erzgebirge. The monazite ThO2*-PbO data define isochrones between 323±10 and 360±10 Ma, with most samples around 340 Ma, interpreted as the ages of Variscan regional metamorphism. Several samples bear an older minor monazite population at ages between 415 to 432 Ma. Special regard has been dedicated to met

The Variscan granites from the Western Erzgebirge were repeatedly dated by various methods, but no consensus has been reached about their exact intrusion ages. This study presents a multi-dating approach for the four largest intrusions from the Western Erzgebirge (Aue-Schwarzenberg, Bergen, Eibenstock, Kirchberg). We analysed several samples from each pluton/suite with zircon U-Pb CA-ID-TIMS (chemical abrasion-isotope dilution-thermal ionization mass spectrometry) to obtain robust temporal information on their age and tempo of intrusion. These data enable us for the first time to define three intrusive episodes of 1-2 Ma each, separated by quiet periods of several Ma. The Aue-Schwarzenberg suite represents the oldest granites that intruded at similar to 323-322 Ma followed by the granites from Bergen and Kirchberg 2-4 Ma later. The highly evolved ore-bearing granites from the Eibenstock pluton intruded after a time lag of similar to 5 Ma at similar to 315-314 Ma. The new data show that there is a resolvable age difference between the two known granite groups. Granite group 2 (also assigned as younger igneous complex, represented by the Eibenstock pluton) is >= 5 Ma younger than granite group 1 (assigned as older igneous complex, represented by granites from Aue-Schwarzenberg, Bergen and Kirchberg). Protracted magmatism and late-/post-magmatic fluid flow partly reset the U-Pb system of these granites to variable degrees, making a precise and accurate dating of their intrusion ages challenging. Pb loss in zircons is often combined with high common Pb (Pb-c). SHRIMP/SIMS (sensitive high mass resolution ion microprobe/secondary ion mass spectrometry) and LA-ICP-MS (laser ablation-inductively coupled plasma-mass spectrometry) on non-CA zircons document that Pb loss and high Pb c is quite variable within zircon grains and may be located in micro-fractures. We demonstrate that chemical abrasion (CA) clearly minimizes or removes both Pb loss and Pb-c. Results from prior LA

Gongylolepis is composed for 15 species, endemic to the Guyana region. This is the largest genus of tribe Mutiseae in the area. Palynological features have been studied for some members of the Mutiseae, but not for Gongylolepis. We studied the pollen morphology of nine species of the genus, using samples from herbarium material. The observations were made in 10 to 15 pollen grains for species and features of the spines, colpus, polar axis, equatorial diameter, exine structure, pollen type, apertures, perforations and P/E ratio to determinate pollen shape, were analyzed. Observations and pictures were made with light microscope and scanning electron microscope. With this information, a matrix and conglomerate analysis was made. Gongylolepis pollen is tricolporate, spheroidal and mainly of great size. Differences in exine ornamentation were enough to discriminate the studied species. Spines are conical, with perforations near of the base, but with differences in the apex shape. The dendogram showed four groups, where the size, shape, exine ornamentation, spines, colpus and perforations were of importance to the classification of the species considered, Gongylolepis está constituido por 15 especies, circunscritas a la región de Guayana, al norte de Suramérica. Es el género más numeroso de la tribu Mutisieae en dicha región, representado en su flora por especies endémicas. Aunque algunas especies de Mutisieae han sido estudiadas palinológicamente por varios investigadores, no hay estudios de las especies de Gongylolepis. En este trabajo se analizan los caracteres morfológicos del polen de nueve especies de Gongylolepis, de la Guayana venezolana. Las muestras de polen provienen de material de distintas colecciones de herbario. Para la observación de los caracteres de polen se usaron de 10 a 15 granos por especie, se analizaron caracteres de las espinas, colpos, eje polar, diámetro ecuatorial, ornamentación y grosor de la exina, tipo de polen, apertura, presencia de perforaciones, y la relación P/E para determinar forma de los granos. Las observaciones y fotografías se realizaron mediante MEB y MEL. Con la información obtenida, se elaboró una matriz y se realizó un análisis de conglomerados. Como resultado, se encontró que el polen de Gongylolepis es tricolporado, con aspecto esferoidal y principalmente de gran tamaño. Presentó diferencias en la ornamentación de la exina, lo cual permitió separar las especies estudiadas. Las espinas son cónicas, sin embargo se encontraron diferencias en cuanto a la forma del ápice, además se observaron perforaciones cercanas a la base de éstas. El dendrograma obtenido mostró cuatro agrupamientos, donde los caracteres analizados, como tamaño, forma, ornamentación, espinas, colpos y perforaciones, fueron de gran importancia para clasificar las especies bajo estudio.

Gongylolepis is composed for 15 species, endemic to the Guyana region. This is the largest genus of tribe Mutiseae in the area. Palynological features have been studied for some members of the Mutiseae, but not for Gongylolepis. We studied the pollen morphology of nine species of the genus, using samples from herbarium material. The observations were made in 10 to 15 pollen grains for species and features of the spines, colpus, polar axis, equatorial diameter, exine structure, pollen type, apertures, perforations and P/E ratio to determinate pollen shape, were analyzed. Observations and pictures were made with light microscope and scanning electron microscope. With this information, a matrix and conglomerate analysis was made. Gongylolepis pollen is tricolporate, spheroidal and mainly of great size. Differences in exine ornamentation were enough to discriminate the studied species. Spines are conical, with perforations near of the base, but with differences in the apex shape. The dendogram showed four groups, where the size, shape, exine ornamentation, spines, colpus and perforations were of importance to the classification of the species considered, Gongylolepis está constituido por 15 especies, circunscritas a la región de Guayana, al norte de Suramérica. Es el género más numeroso de la tribu Mutisieae en dicha región, representado en su flora por especies endémicas. Aunque algunas especies de Mutisieae han sido estudiadas palinológicamente por varios investigadores, no hay estudios de las especies de Gongylolepis. En este trabajo se analizan los caracteres morfológicos del polen de nueve especies de Gongylolepis, de la Guayana venezolana. Las muestras de polen provienen de material de distintas colecciones de herbario. Para la observación de los caracteres de polen se usaron de 10 a 15 granos por especie, se analizaron caracteres de las espinas, colpos, eje polar, diámetro ecuatorial, ornamentación y grosor de la exina, tipo de polen, apertura, presencia de perforaciones, y la relación P/E para determinar forma de los granos. Las observaciones y fotografías se realizaron mediante MEB y MEL. Con la información obtenida, se elaboró una matriz y se realizó un análisis de conglomerados. Como resultado, se encontró que el polen de Gongylolepis es tricolporado, con aspecto esferoidal y principalmente de gran tamaño. Presentó diferencias en la ornamentación de la exina, lo cual permitió separar las especies estudiadas. Las espinas son cónicas, sin embargo se encontraron diferencias en cuanto a la forma del ápice, además se observaron perforaciones cercanas a la base de éstas. El dendrograma obtenido mostró cuatro agrupamientos, donde los caracteres analizados, como tamaño, forma, ornamentación, espinas, colpos y perforaciones, fueron de gran importancia para clasificar las especies bajo estudio.

The objective of this work is to determine flame properties useful for the advancement of combustion system modeling procedures and design aids, particularly in areas related to the interactions between flame turbulence properties and high temperature combustion chemistry. Toward this goal, measurements have been made of flame structure important for understanding and verifying the basic assumptions upon which the models are based. Thus, we have used spontaneous Raman scattering to determine average and excursion values of the flame front and the viscous superlayer for a co-flowing jet turbulent diffusion flame, and planar laser-induced fluorescence to provide two- dimensional instantaneous images of the flame reaction zones themselves over a range of Reynolds numbers.

The overall objective of this work is to provide a scientific basis for a new non-perturbing, space- and time-resolved optical probe of gas temperature and constituency in combustion systems. The major part of the effort is focussed on the development of Raman scattering methods to accomplish this goal. Effort is also directed toward the goal of using other compatible measurement techniques (viz., laser velocimetry) in an integrated probe system for flame characterization. (Author), Prepared in cooperation with General Electric Corporate Research and Development, Schenectady, NY, Rept. no. 82SRD086.

The objective of this work is to apply light scattering diagnostics to the study of a well-defined combustion flow. Product gas densities are measured for a turbulent jet diffusion flame through use of vibrational Raman scattering techniques. These are combined with simultaneous temperature data from Raman scattering and near-simultaneous velocity data from laser velocimetry, to give an integrated probe system for basic flame properties.

Coherent anti-Stokes spectroscopy (CARS) can be considerably simpler than is suggested by literature analyses based on interactions of monochromatic waves. The simplification arises when the optical properties of real lasers are incorporated into the analysis. To incorporate these properties, it is necessary to recognize that the underlying nonlinear optical interaction has a previously ignored complexity and is dependent on the coherence properties of the fields as well as on their spectra. The coherence of the interaction, as described by the CARS linewidth parameter, is degraded by the imperfect coherence of the laser sources. The occurrence of the nonlinear interaction depends on the small size of laser mode widths, or more fundamentally, on the statistical degeneration of each incident field into a small number of independent fields, a property possessed only by optical fields from lasers. If the lasers' contributions to the linewidth parameter are made dominant, the degree of coherence becomes a fixed property of the apparatus, simplifying interpretation of CARS spectra and extending the range of usefulness of CARS well beyond what would otherwise be expected. Available numerical values plus considerations of effects such as mode frequency chirp suggest that domination of the coherence by the apparatus can be arranged or at least approached in most cases.

A simplified method of calculation of the contour of a totally polarized Raman band for an asymmetric top molecule in the gaseous state has been applied to the v1-band of the water molecule. The good fits between computed and experimental contours from approximately 150 to 350C lay the foundation for temperature determinations for water vapor from measurements of the Raman band profile.

Methods based upon light-scattering techniques for the three-dimensional measurement of density, temperature, and velocity are evaluated for application to wind tunnel studies over wide ranges of the state variables for air: 0.001 to 100 psia, 30 to 2000R, and 0 to 5000 feet per second. Recommended approaches are laser Doppler velocimetry for velocity measurement and rotational and vibrational Raman scattering for temperature and density measurement. The laser Doppler velocimeter technique is in an advanced stage of development and its implementation is discussed in detail. The Raman approach is innovative and has been selected on the basis of potential advantages over alternative approaches. Although the projected capabilities are analyzed and presented in detail, the recommended system has not as yet been implemented in the laboratory. The Raman techniques are shown to be applicable over the entire range of flow parameters, which correspond to the pressure-temperature loci from stagnation conditions to the design point for the three major test facilities under consideration at Wright-Patterson Air Force Base. (Author Modified Abstract)

Representative theoretical and experimental studies relating to the determination of gaseous radiation from isothermal systems are discussed. The following recently concluded studies are described: f-number measurements for OH behind shock fronts; a method for the direct determination of radiative and collisional life times of vibrationally excited, molecules; emissivity calculations for CO_2; emissivity calculations for a hydrogen plasma at temperatures up to about 10,000°K.