The composition of hornblende, grunerite, and garnet in Archean iron formation of the Itchen Lake area, District of Mackenzie, Canada

1977 ◽  
Vol 14 (8) ◽  
pp. 1740-1752
Author(s):  
Hewitt H. Bostock
Keyword(s):  
Oxygen Fugacity ◽  
Electron Microprobe ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Metamorphic Grade ◽  
The Other ◽  
Alumina Content ◽  
Iron Formation ◽  
Lake Area ◽  
Factors Affecting

The compositions of seven pairs of coexisting hornblende and grunerite and five assemblages of coexisting hornblende, grunerite, and garnet from Archean silicate iron formation of low and medium metamorphic grade have been obtained by electron microprobe analysis. Important factors affecting the composition of the amphiboles are: (1) the Mg/Fe ratio of the iron-formation beds, which controls the gross Mg/Fe ratio of the amphiboles; (2) the alumina content of the beds, which affects the degree of alumina substitution in hornblende thereby altering the distribution of Mg and Fe in the coexisting amphiboles; and (3) the occurrence of iron-rich garnet, which produces higher Mg/Fe ratios in both amphiboles. A fourth potentially important factor, the oxygen fugacity, cannot be satisfactorily assessed with these data, but has not obscured the effects of the other three. Temperature of crystallization of the amphiboles was an important factor mainly insofar as it affected the crystallization of garnet in the alumina-rich rocks.Four coexisting hornblende–cummingtonite pairs from metatuffs show similar control of Mg–Fe fractionation by alumina substitution in hornblende.

MICROSCOPY AND ELECTRON MICROPROBE ANALYSIS OF SOME IRON–MANGANESE PANS FROM NEWFOUNDLAND

1973 ◽  
Vol 53 (4) ◽  
pp. 349-361 ◽  
Author(s):  
R. BREWER ◽  
R. PROTZ ◽  
J. A. McKEAGUE
Keyword(s):  
Electron Microprobe ◽  
Light Microscope ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
The Other ◽  
Reflected Light ◽  
Fe And Mn ◽  
Iron Manganese ◽  
Mn Concentrations

A number of thin iron–manganese pans from soils with peaty surface horizons have been examined with a light microscope and electron microprobe analyzer. The results show that: (1) concentrations of Fe and Mn (as oxides, hydroxides, or both) occur distinctly separated from each other even where closely associated, i.e., every unit analyzed was dominantly either Mn or Fe with little contamination by the other; (2) Mn concentrations always increase in proportion to Fe with increasing depth in the pans; generally Mn concentrations underlie Fe concentrations; (3) at least in these pans, the various kinds of Fe and Mn concentrations can be distinguished optically by using both transmitted and reflected light characteristics.

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

2014 ◽  
Vol 18 (1) ◽  
pp. 39-44 ◽  
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

<p>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 Al<sup>VI</sup> 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 (fO<sub>2</sub>) 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.</p><p> </p><p><strong>Resumen</strong></p><p>El 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.</p>

THE MICROMORPHOLOGY AND ELECTRON MICROPROBE ANALYSIS OF TWO RESIDUAL SOILS, ONE DEVELOPED ON GRANITE, THE OTHER ON MARBLE, IN PETERBOROUGH COUNTY, ONTARIO

1972 ◽  
Vol 52 (1) ◽  
pp. 79-89 ◽  
Author(s):  
J. E. GILLESPIE ◽  
R. PROTZ
Keyword(s):  
Clay Minerals ◽  
Outer Layer ◽  
Electron Microprobe ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Granite Gneiss ◽  
The Other ◽  
Residual Soils ◽  
Quartz Grains

Micromorphological studies of two residual soils have revealed a constant mineralogy with depth in each soil and maximum cutan development in the B horizon. Electron microprobe analysis has shown iron, titanium, and carbon in all of the cutans. Calcium was present in the cutans around feldspar grains in the Methuen, a soil derived from granite gneiss, but was not present in the cutans around quartz grains. The inner layer of the grain cutans consisted of iron and titanium, the outer layer having in addition silica and aluminum. These latter elements were indicators of clay minerals. Microprobe analysis of mica grains indicated losses of magnesium and potassium from the mica in the A horizons of both soils compared with the levels of these elements present in the mica in the C1 horizons.

Scanning Electron Microscopy and Electron Microprobe Analysis of Malignant Cell Cultures

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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