Liquation Differentiation of Komatiites: Features of Isotopic–Geochemical Composition of Rocks, Age, and Petrological–Geodynamic Implications (Using the Example of the Kostomuksha Greenstone Structure, Fennoscandian Shield)

This paper presents the data on the structure and composition of a concentric-zonal komatiite pillow from the Ruvinvaar Formation of the Neo-Archean Kostomuksha greenstone structure of the Fennoscandian Shield. The features of the zonal pillow structure include a narrow range of variations in concen...

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Bibliographic Details
Published in:Geology of ore deposits 2023-12, Vol.65 (8), p.921-932
Main Author: Vrevsky, A. B.
Format: Article
Language:English
Subjects:
Age
Andesite
Basalt
Bedding
Composition
Differentiation
Earth and Environmental Science
Earth Sciences
Komatiites
Mineral Resources
Pillow structures
Rare earth elements
Rocks
Systematics
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Summary:This paper presents the data on the structure and composition of a concentric-zonal komatiite pillow from the Ruvinvaar Formation of the Neo-Archean Kostomuksha greenstone structure of the Fennoscandian Shield. The features of the zonal pillow structure include a narrow range of variations in concentrations of rare-earth elements (REEs), similar REE patterns of dacite and andesite from the pillow core and komatiite and komatiitic basalt from the outer part, and higher REE contents of andesite relative to dacite. These features of REE distribution indicate liquation differentiation of basic melts. According to the Sm–Nd isotopic systematics of rocks of the komatiite matrix and dacite, their isochron age is 2874 ± 35 Ma (εNd = +1.5). Our data indicate an older (than was previously considered) age of the Kontok Group of the Kostomuksha greenschist structure.
ISSN:1075-7015
1555-6476
DOI:10.1134/S107570152308010X