Chemical Th–U–total Pb dating by electron microprobe analysis of monazite, xenotime and zircon from the Archean Napier Complex, East Antarctica: evidence for ultra-high-temperature metamorphism at 2400 Ma

The technique of electron microprobe analysis is extremely useful in the rapidly changing field of high temperature superconductivity. Since the properties of the oxide superconductors depend strongly on the oxygen concentration, it is important to be able to measure oxygen as accurately as possible. It is particularly useful to know unambiguously the composition of small single crystals, which either grow with good smooth surfaces (for example in the Y-Ba-Cu-O system) or can be easily cleaved (for example the Bi-Sr-Cu-O system) to provide excellent surface quality without polishing. The Bi2+xSr2-x,CuO6±z (BSCO) crystals are extremely soft and layer like, which makes polishing difficult, and another advantage of cleaving is that the crystal does not have to be embedded in epoxy, and can thus be relatively easily removed from its mount for subsequent annealing treatments or other experiments. The disadvantage of mounting in this manner is the existence of small tilt angles, because the thin crystals bend a little when they are cleaved.

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Composition of biotite within the Wushan granodiorite, Jiangxi Province, China: Petrogenetic and metallogenetic implications

Earth Sciences Research Journal ◽

10.15446/esrj.v18n1.40830 ◽

2014 ◽

Vol 18 (1) ◽

pp. 39-44 ◽

Cited By ~ 2

Author(s):

Qian Dong ◽

Yangsong Du ◽

Zhenshan Pang ◽

Wenrui Miao ◽

Wei Tu

Keyword(s):

High Temperature ◽

Oxygen Fugacity ◽

Electron Microprobe ◽

Microprobe Analysis ◽

Electron Microprobe Analysis ◽

Copper Deposit ◽

Jiangxi Province ◽

Hydrothermal Mineralization ◽

Type Granite ◽

Formation Conditions

The Wushan skarn copper deposit is genetically associated with the Wushan granodiorite. In this study, we investigate the petrography and mineralogy of biotites within the Wushan granodiorite. We also determine the formation conditions of these biotites and discuss the significance of these minerals in terms of petrogenesis and mineralization. Electron microprobe analysis shows that biotites within the Wushan granodiorite are Magnesio-biotites that contain relatively high Mg and Ti concentrations and low Fe and Al concentrations. The ionic coefficient of AlVI in these biotites ranges from 0.03 to 0.19, with SFeO/(SFeO + MgO) ratios that range from 0.531–0.567 and MgO concentrations that range from 12.80–14.06 wt%. These results indicate that the Wushan granodiorite is an I-type granite. The Wushan biotites crystallized at temperatures (T) of 720°C–750°C, with oxygen fugacity (fO2) conditions of –11.6 to –12.5 and pressures (P) of 0.86–1.03 kb. These conditions are indicative of a crystallization depth (H) of 2.84–3.39 km. These data also indicate that the Wushan granodiorite developed under conditions of high temperature and high oxygen fugacity, suggesting that the Wushan granodiorite is prospective for magma-hydrothermal mineralization and that this granodiorite probably contributed to the formation of the Wushan skarn copper deposit. ResumenEl depósito de skarn cuprífero de Wushan está asociado genéticamente con la granodiorita de Wushan. En este estudio se investiga la petrografía y mineralogía de biotitas de la granodiorita de Wushan. Se determinan también las condiciones de formación de estas biotitas y se discute la significación de estos minerales en términos de petrogénesis y mineralización. Un análisis de microsonda a electrones muestra que las biotitas de la granodiorita de Wushan son biotitas de magnesio que contienen altas concentracionesrelativas de Mg y Ti y bajas de Fe y Al. El coeficiente icónico de AlVI en estas biotitas oscila entre 0,03 y 0,19, con índices SFeO/(SFeO + MgO) que oscilan entre 0,531-0,567 y concentraciones de MgO que van desde 12,80 a 14,06 wt%. Estos resultados indican que la granodiorita de Wushan es de granito tipo I. Las biotitas de Wushan se cristalizaron a temperaturas (T) de 720°C–750°C, con condiciones de fugacidad del oxígeno (fO2) de -11,6 a -12,5 y presión (P) de O,86 a 1,03 kb. Estas condiciones indican una profundidad de cristalización (H) de 2,84-3,39 kilómetros. Los datos también indican que la granodiorita de Wushan se desarrolló bajo condiciones de alta temperatura y alta fugacidad de oxigeno, lo que sugiere que la granodiorita de Wushan tiene potencial para la mineralización magmática-hidrotérmica y que esta granodiorita probablemente contribuyó a la formación del depósito de skarn cuprífero de Wushan.

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Characterization of high-temperature superconductors by electron microprobe analysis

Microchimica Acta ◽

10.1007/bf01244481 ◽

1992 ◽

Vol 107 (3-6) ◽

pp. 273-277 ◽

Cited By ~ 1

Author(s):

Theodor H. G. Hehenkamp

Keyword(s):

High Temperature ◽

Electron Microprobe ◽

Microprobe Analysis ◽

Electron Microprobe Analysis ◽

High Temperature Superconductors

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Geochemical Characterization of Zircon in Fyfe Hills of the Napier Complex, East Antarctica

Minerals ◽

10.3390/min10110943 ◽

2020 ◽

Vol 10 (11) ◽

pp. 943

Author(s):

Mami Takehara ◽

Kenji Horie ◽

Tomokazu Hokada

Keyword(s):

High Temperature ◽

East Antarctica ◽

Group Iii ◽

Group I ◽

Group Ii ◽

Uht Metamorphism ◽

Ree Patterns ◽

High Temperature Metamorphism ◽

Napier Complex

Ultra-high temperature (UHT) metamorphism plays an essential role in the development and stabilization of continents through accretionary and collisional orogenesis. The Napier Complex, East Antarctica, preserves UHT metamorphism, and the timing is still debated. U–Pb zircon geochronology integrated with rare earth element (REE) and oxygen isotope was applied to a garnet-bearing quartzo-feldspathic gneiss to confirm the timing of UHT metamorphism in Fyfe Hills in the western part of the Napier Complex. The zircons are analyzed using a sensitive high-resolution ion microprobe (SHRIMP). The cathodoluminescence observation and U–Pb ages allowed us to classify the analytical domains into three types: inherited domains (Group I), metamorphic domains (Group II), and U–Pb system disturbed domains (Group III). The REE patterns of Group II are characterized by a weak fractionation between the middle REE and heavy REE, which reinforces the above classification. The 207Pb*/206Pb* ages of Group II have an age peak at 2501 Ma, therefore, the gneiss experienced high temperature metamorphism at 2501 Ma. δ18O of zircons are homogeneous among the three groups (5.53 ± 0.11‰, 5.51 ± 0.14‰, and 5.53 ± 0.23‰), which suggests re-equilibration of oxygen isotopes after metamorphism at ca. 2501Ma under dry UHT conditions.

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Scanning Electron Microscopy and Electron Microprobe Analysis of Malignant Cell Cultures

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100100561 ◽

1968 ◽

Vol 26 ◽

pp. 164-165

Author(s):

R. I. Johnsson-Hegyeli ◽

A. F. Hegyeli ◽

D. K. Landstrom ◽

W. C. Lane

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Cell Cultures ◽

Electron Microprobe ◽

Microprobe Analysis ◽

Electron Microprobe Analysis ◽

Three Dimensional ◽

Malignant Cell ◽

Interference Microscopy ◽

Scanning Electron

Last year we reported on the use of reflected light interference microscopy (RLIM) for the direct color photography of the surfaces of living normal and malignant cell cultures without the use of replicas, fixatives, or stains. The surface topography of living cells was found to follow underlying cellular structures such as nuceloli, nuclear membranes, and cytoplasmic organelles, making possible the study of their three-dimensional relationships in time. The technique makes possible the direct examination of cells grown on opaque as well as transparent surfaces. The successful in situ electron microprobe analysis of the elemental composition and distribution within single tissue culture cells was also reported.This paper deals with the parallel and combined use of scanning electron microscopy (SEM) and the two previous techniques in a study of living and fixed cancer cells. All three studies can be carried out consecutively on the same experimental specimens without disturbing the cells or their structural relationships to each other and the surface on which they are grown. KB carcinoma cells were grown on glass coverslips in closed Leighto tubes as previously described. The cultures were photographed alive by means of RLIM, then fixed with a fixative modified from Sabatini, et al (1963).

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