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Metamorphic effects on agate found near the Shap Granite, Cumbria, England; as demonstrated by petrography, X-ray diffraction and spectroscopic methods

T. Moxon, S. J. B. Reed and M. Zhang
Metamorphic effects on agate found near the Shap Granite, Cumbria, England; as demonstrated by petrography, X-ray diffraction and spectroscopic methods
Mineralogical Magazine (August 2007) 71 (4): 461-476

Abstract

Agates from a 430 Ma host at Stockdale Beck, Cumbria, England have been characterized. The crystallite size of the Stockdale Beck agates was found to be approximately 60% greater than any other agates from five regions aged 400-1100 Ma. Raman spectroscopy identified moganite in all agates tested except those from Stockdale Beck. Infrared spectroscopy showed that the silanol content of the Stockdale Beck agates was near zero. The properties of agates from Stockdale Beck and the 1.84-3.48 Ga metamorphosed hosts found in Western Australia were similar but different from agates found in other hosts aged 400-1100 Ma. Cathodoluminescence demonstrates further differences between agates from hosts aged 13-1100 Ma and those from Stockdale Beck and Western Australia. Agates from the latter areas have a lower proportion of defects causing a red emission band (approximately 660 nm) but an increased proportion of defects causing blue (approximately 470 nm) and orange (approximately 640 nm) emission bands. Agates found in hosts aged 13-1100 Ma are also differentiated from the Stockdale Beck and Western Australian agates in a ternary plot of the relative intensities of violet to blue to orange emission bands. Single scans producing this combination of colours are only found in the Stockdale Beck and Western Australian agates. The properties shown by the Stockdale Beck and Western Australian agates demonstrate that an agate or chalcedony infill can be used to identify post-deposition palaeoheating within a host rock.


ISSN: 0026-461X
EISSN: 1471-8022
Coden: MNLMBB
Serial Title: Mineralogical Magazine
Serial Volume: 71
Serial Issue: 4
Title: Metamorphic effects on agate found near the Shap Granite, Cumbria, England; as demonstrated by petrography, X-ray diffraction and spectroscopic methods
Affiliation: 55 Common Lane, Auckley, Doncaster, United Kingdom
Pages: 461-476
Published: 200708
Text Language: English
Publisher: Mineralogical Society, London, United Kingdom
References: 37
Accession Number: 2008-068249
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 4 tables
N54°04'60" - N55°15'00", W03°40'00" - W02°10'00"
S35°00'00" - S14°00'00", E113°00'00" - E129°00'00"
Secondary Affiliation: University of Cambridge, GBR, United Kingdom
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 200817
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