Photo-emission electron microscopy (PEEM) heating investigations of a natural amphibole sample

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Authors:Wartho, J. A.
Author Affiliations:Primary:
University of Leeds, Department of Earth Sciences, Leeds, United Kingdom
Volume Title:Mineralogical Magazine
Source:Mineralogical Magazine, 59(1), p.121-127. Publisher: Mineralogical Society, London, United Kingdom. ISSN: 0026-461X
Publication Date:1995
Note:In English. 19 refs.; illus.
Summary:PEEM allows 'real-time' observations to be made of solid-state transformations and other high-temperature processes taking place during vacuum-heating up to c. 2000°C The solid state transformations of an amphibole-rich hornblendite specimen have been observed in the temperature range of 750-1000°C (± 50°C Between c. 970-990°C a rapid change in orientation contrast was observed, indicating a structural rearrangement from an oxyhornblende crystal lattice to a clinopyroxene structure. This phase retains the original amphibole shape and texture (including two 120°C intersecting cleavage traces), but possesses a clinopyroxene crystal structure. At higher temperatures this phase is seen to decompose, forming iron oxides and other fine-grained products. PEEM has provided useful information on both the nature and rates of transformation of natural amphiboles which has proved invaluable in our understanding of the mineralogically-controlled mechanisms of argon release during 40Ar/39Ar dating of amphibole samples.
Subjects:Absolute age; Amphibole group; Applications; Ar-40/Ar-39; Ar/Ar; Argon; Chain silicates; Clinopyroxene; Crystal structure; Emission spectroscopy; Experimental studies; Isotope ratios; Isotopes; Methods; Noble gases; Pyroxene group; Radioactive isotopes; Silicates; Spectroscopy; Stable isotopes; Thermal recovery
Abstract Numbers:95M/1651
Record ID:1995049862
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland
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