Mechanisms of Ar release from Himalayan metamorphic hornblende.

Wartho, J.-A. , Dodson, M.H., Rex, D.C. and Guise, P.G. (1991) Mechanisms of Ar release from Himalayan metamorphic hornblende. American Mineralogist, 76 . pp. 1446-1448.

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Abstract

Changes in hornblende samples that occur during stepwise 39Ar/40Ar analysis were studied
experimentally and mineralogically. A complex succession of reactions was seen (hornblende
~ oxyhornblende ~ clinopyroxene-structured phase ~ fine-grained reaction products
~ glasses) in the temperature range 750-1300 °C. The release of Ar from hornblende
in the vacuum furnace appeared to occur by fundamentally different processes from those
resulting in Ar loss during metamorphism. Simple diffusional interpretations of the release patterns are, therefore, not capable of revealing the thermal history of samples. In principle, some useful information may be obtained if long-standing fractures andother defects control both natural Ar loss and mineral reactions within the laboratory.

Document Type: Article
Keywords: hornblende; Himalaya; Ar release
Refereed: Yes
ISSN: 0003-004X
Date Deposited: 24 Nov 2015 10:50
Last Modified: 24 Nov 2015 10:50
URI: http://oceanrep.geomar.de/id/eprint/30295

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