Skip to Main Content
GEOREF RECORD

A rapid and precise quantitative electron probe chemical mapping technique and its application to an ultrahigh-pressure eclogite from the Moldanubian Zone of the Bohemian Massif (Nove Dvory, Czech Republic)

Atsushi Yasumoto, Kenta Yoshida, Tatsu Kuwatani, Daisuke Nakamura, Martin Svojtka and Takao Hirajima
A rapid and precise quantitative electron probe chemical mapping technique and its application to an ultrahigh-pressure eclogite from the Moldanubian Zone of the Bohemian Massif (Nove Dvory, Czech Republic)
American Mineralogist (October 2018) 103 (10): 1690-1698

Abstract

Quantitative X-ray mapping using an electron probe enables quantitative evaluation of inhomogeneities within rocks. Recent studies have proposed methods to construct quantitative chemical maps by combining X-ray maps with referential spot analyses within a mapped area. These approaches address matrix effects by assuming each pixel in the mapped area represents a single phase. In such cases, the spatial resolution of the X-ray maps must be sufficiently high to separate mineral phases. This study proposes a new procedure to reliably quantify centimeter-scale X-ray maps even if the maps contain an ineligible number of pixels analyzing multiple phases because of a large mapping probe diameter. Such multi-phase pixels are statistically classified into their constituent phases by introducing a distribution-based clustering analysis. Furthermore, based on referential spot analyses, we implemented corrections for matrix effects and the backgrounds of single- and multi-phase pixels. Our technique, termed QntMap, was developed as an open source R package and distributed on a social coding platform, GitHub (https://github.com/atusy/qntmap). We applied QntMap to calculate local bulk compositions within an ultrahigh-pressure eclogite from Nove Dvory, Czech Republic. The studied sample is a garnet-rich bimineralic eclogite that includes a 3 mm thick pyroxene-rich layer. A mapped area is approximately 3 X 1 cm in size and oriented normal to the layer. A profile normal to the layer shows increases in Cr (sub 2) O (sub 3) (0.0 to 0.3 wt%) and XMg [Mg/(Fe+Mg) = 0.5 to 0.8] from the garnet-rich matrix toward the pyroxene-rich layer. A large variation in XMg and high-Cr (sub 2) O (sub 3) contents in the pyroxene-rich layer are inconsistent with a cumulate origin. We suggest that the pyroxene-rich layer was derived from a pyroxenitic melt that intruded the eclogite.


ISSN: 0003-004X
EISSN: 1945-3027
Coden: AMMIAY
Serial Title: American Mineralogist
Serial Volume: 103
Serial Issue: 10
Title: A rapid and precise quantitative electron probe chemical mapping technique and its application to an ultrahigh-pressure eclogite from the Moldanubian Zone of the Bohemian Massif (Nove Dvory, Czech Republic)
Affiliation: Kyoto University, Department of Geology and Mineralogy, Kyoto, Japan
Pages: 1690-1698
Published: 201810
Text Language: English
Publisher: Mineralogical Society of America, Washington, DC, United States
References: 30
Accession Number: 2019-007180
Categories: Igneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
N49°57'00" - N50°00'00", E15°19'00" - E15°22'00"
Secondary Affiliation: Japan Agency for Marine-Earth Science and Technology, JPN, JapanJapan Science and Technology Agency, JPN, JapanOkayama University, JPN, JapanCzech Academy of Sciences, Institute of Geology, CZE, Czech Republic
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Abstract, copyright, Mineralogical Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201906
Close Modal

or Create an Account

Close Modal
Close Modal