New isotope–geochemical and mineralogical data on the ultramafic xenoliths in the volcanic rocks of the Kamchatka–Koryak region: Two types of mantle protolith in the modern island-arc system
- Authors: Koloskov A.V.1, Martynov Y.A.2, Ananiev V.V.1
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Affiliations:
- Institute of Volcanology and Seismology, Far East Branch
- Far East Geological Institute, Far East Branch
- Issue: Vol 11, No 2 (2017)
- Pages: 95-109
- Section: Article
- URL: https://journals.rcsi.science/1819-7140/article/view/211221
- DOI: https://doi.org/10.1134/S1819714017020051
- ID: 211221
Cite item
Abstract
The paper presents new isotope–geochemical and mineralogical data on mantle xenoliths of the “island-arc” (Avacha, Shiveluch, and Kharchinsky volcanoes) and “within-plate” (Valovayam River, Cape Navarin, and Bakening Volcano areas) types. In terms of paragenesis and mineral composition, the “islandarc” xenoliths correspond to the olivine–plagioclase depth facies, while the “within-plate” xenoliths came from spinel lherzolite to wehrlite facies, which is transitional to the olivine–plagioclase equilibrium. The majority of the “within-plate” xenoliths are enriched in high-field-strength elements (Ti, Nb, Hf, Zr, Yb). The “island-arc” xenoliths in general are depleted in REE, while the “within-plate” xenoliths are enriched in all REE. The former have low Pb isotope ratios, being in isotope equilibrium with lower crustal basites, while most of the latter group are enriched in radiogenic Pb. The island-arc xenoliths are of magmatic origin and were derived from the sublithospheric crust–mantle mixture, while the “within-plate” xenoliths reflect the composition of the asthenospheric mantle source. The primary appearance of the xenoliths is obliterated by secondary recrystallization and metasomatic reworking.
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About the authors
A. V. Koloskov
Institute of Volcanology and Seismology, Far East Branch
Author for correspondence.
Email: kolosav@kscnet.ru
Russian Federation, bul’v. Piipa 9, Petropavlovsk-Kamchatskii, 683006
Yu. A. Martynov
Far East Geological Institute, Far East Branch
Email: kolosav@kscnet.ru
Russian Federation, pr. Stoletiya Vladivostoka 159, Vladivostok, 690022
V. V. Ananiev
Institute of Volcanology and Seismology, Far East Branch
Email: kolosav@kscnet.ru
Russian Federation, bul’v. Piipa 9, Petropavlovsk-Kamchatskii, 683006