MEDIUM- TO LOW-PRESSURE PELITIC GNEISSES OF FRASER LAKES ZONE B, WOLLASTON DOMAIN, NORTHERN SASKATCHEWAN, CANADA: MINERAL COMPOSITIONS, METAMORPHIC P-T-t PATH, AND IMPLICATIONS FOR THE GENESIS OF RADIOACTIVE ABYSSAL GRANITIC PEGMATITES

The Mont Albert mafic–ultramafic complex of central Gaspé, Quebec, is generally regarded as a partial ophiolite with an underlying metamorphic sole. The metamorphic rocks include a number of mineralogical and textural varieties of amphibolite, including some migmatite, as well as minor metasedimentary and quartzo-feldspathic gneisses. The most intriguing rocks in the complex are mafic to ultramafic garnet- and clinopyroxene-bearing amphibolites that are restricted to the vicinity of the peridotite contact. These rocks have unusual Fe-rich, Si-poor bulk compositions and may represent tholeiites chemically modified by interaction with fluid or melt before or during metamorphism. These amphibolites are not retrograde eclogites, since andesine was present throughout the metamorphic history, and the clinopyroxene is not omphacitic. Coexisting mineral compositions and temperature estimates overlap for core, rim, and matrix grains of all the major phases in the garnet–clinopyroxene amphibolites, implying equilibration in the range 750–800 °C at 8–9 kbar (1 kbar = 100 MPa). Garnet amphibolites lacking clinopyroxene yielded somewhat lower P–T estimates of 600–700 °C and 6–7 kbar. Owing to complex field relationships, it is not clear whether or not these P–T conditions resulted from evolution along a single P–T–t path.

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Time calibration of a P-T path from a Variscan high-temperature low-pressure metamorphic complex (Bayerische Wald, Germany), and the detection of inherited monazite

Contributions to Mineralogy and Petrology ◽

10.1007/s004100050014 ◽

2000 ◽

Vol 138 (2) ◽

pp. 143-163 ◽

Cited By ~ 63

Author(s):

Angelika Kalt ◽

Fernando Corfu ◽

Jan R. Wijbrans

Keyword(s):

High Temperature ◽

Low Pressure ◽

Metamorphic Complex ◽

Time Calibration ◽

T Path

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Metamorphism of the Central Bundelkhand Greenstone Complex, Indian Shield: Mineral Compositions, Paragenesises, and P–T Path

Petrology ◽

10.1134/s0869591121040056 ◽

2021 ◽

Vol 29 (4) ◽

pp. 404-438

Author(s):

O. S. Sibelev ◽

A. I. Slabunov ◽

S. Mishra ◽

V. K. Singh

Keyword(s):

Indian Shield ◽

Mineral Compositions ◽

T Path

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Effects of Electrical Discharges in Low Pressure Gases on the Morphology of Polyethylene Crystals

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100052730 ◽

1974 ◽

Vol 32 ◽

pp. 544-545

Author(s):

L.H. Bolz ◽

D.H. Reneker

Keyword(s):

Power Distribution ◽

Electrical Discharge ◽

Dielectric Breakdown ◽

Ionic Species ◽

Low Pressure ◽

Polymer Surfaces ◽

Electrical Discharges ◽

Adhesive Bonds ◽

Power Distribution Lines ◽

Modification Of The Surface

The attack, on the surface of a polymer, by the atomic, molecular and ionic species that are created in a low pressure electrical discharge in a gas is interesting because: 1) significant interior morphological features may be revealed, 2) dielectric breakdown of polymeric insulation on high voltage power distribution lines involves the attack on the polymer of such species created in a corona discharge, 3) adhesive bonds formed between polymer surfaces subjected to such SDecies are much stronger than bonds between untreated surfaces, 4) the chemical modification of the surface creates a reactive surface to which a thin layer of another polymer may be bonded by glow discharge polymerization.

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Field ion microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100104236 ◽

1988 ◽

Vol 46 ◽

pp. 434-435

Author(s):

Gert Ehrlich

Keyword(s):

Low Temperature ◽

Sample Surface ◽

Low Pressure ◽

Radius Of Curvature ◽

Field Ion Microscopy ◽

Phosphor Screen ◽

Ion Microscopy ◽

Field Ion Microscope

The field ion microscope, devised by Erwin Muller in the 1950's, was the first instrument to depict the structure of surfaces in atomic detail. An FIM image of a (111) plane of tungsten (Fig.l) is typical of what can be done by this microscope: for this small plane, every atom, at a separation of 4.48Å from its neighbors in the plane, is revealed. The image of the plane is highly enlarged, as it is projected on a phosphor screen with a radius of curvature more than a million times that of the sample. Müller achieved the resolution necessary to reveal individual atoms by imaging with ions, accommodated to the object at a low temperature. The ions are created at the sample surface by ionization of an inert image gas (usually helium), present at a low pressure (< 1 mTorr). at fields on the order of 4V/Å.

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