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Excess argon in amphiboles linked to greenschist facies alteration in the Kamila amphibolite belt, Kohistan island arc system, northern Pakistan; insights from (super 40) Ar/ (super 39) Ar step-heating and acid leaching experiments

J. A. Wartho, D. C. Rex and P. G. Guise
Excess argon in amphiboles linked to greenschist facies alteration in the Kamila amphibolite belt, Kohistan island arc system, northern Pakistan; insights from (super 40) Ar/ (super 39) Ar step-heating and acid leaching experiments
Geological Magazine (September 1996) 133 (5): 595-609

Abstract

A mineralogical and (super 40) Ar/ (super 39) Ar study of 13 hornblendes from the Kamila amphibolite belt and Kamila shear zone in N Pakistan has revealed a correlation between the degree of greenschist-facies alteration and quantity of excess (super 40) Ar. There is also a N-S divide, with amphibole from the N region showing greater degrees of greenschist-facies alteration, brittle deformation and excess (super 40) Ar incorporation compared to the predominantly plastically deformed, less altered amphibole samples from the Kamila shear zone in the S. Acid leaching of two hornblendes from the Kamila amphibolite belt indicates that a large proportion of the excess (super 40) Ar is correlated with later greenschist-facies alteration phases, and can be easily removed by acid etching, thus revealing acceptable regional (super 40) Ar/ (super 39) Ar plateau ages of approximately 76 + or - 4 m.y.


ISSN: 0016-7568
EISSN: 1469-5081
Coden: GEMGA4
Serial Title: Geological Magazine
Serial Volume: 133
Serial Issue: 5
Title: Excess argon in amphiboles linked to greenschist facies alteration in the Kamila amphibolite belt, Kohistan island arc system, northern Pakistan; insights from (super 40) Ar/ (super 39) Ar step-heating and acid leaching experiments
Affiliation: University of Leeds, Leeds, United Kingdom
Pages: 595-609
Published: 199609
Text Language: English
Publisher: Cambridge University Press, London, United Kingdom
References: 56
Accession Number: 1997-010791
Categories: GeochronologyIgneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables, geol. sketch map
N23°34'60" - N37°30'00", E60°15'00" - E75°15'00"
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 199704
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