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Jadeitite in the Syum-Keu ultramafic complex from Polar Urals, Russia; insights into fluid activity in subduction zones

Meng Fancong, Huai-Jen Yang, Alexander B. Makeyev, Ren Yufeng, Ksenia V. Kulikova and Natasha I. Bryanchaninova
Jadeitite in the Syum-Keu ultramafic complex from Polar Urals, Russia; insights into fluid activity in subduction zones
European Journal of Mineralogy (July 2016) Pre-issue publication

Abstract

New major, trace and rare earth element (REE) data, and Sr-Nd isotopic compositions of jadeitite and REE-Hf-O isotopic compositions of zircon in jadeitite of the Syum-Keu ultramafic complex of the Polar Urals are used to constrain its origin and source.The jadeitites have high contents of Na (sub 2) O (12.80-14.56 wt%), Al (sub 2) O (sub 3) (20.30-23.81 wt%), SiO (sub 2) (58.47-59.50 wt%), and are enriched in Sr, Ba, Zr, Hf and depleted in Nb relative to primitive mantle values. Chondrite-normalized REE patterns of the jadeitite display weakly U-shaped distribution patterns, with La (sub N) /Yb (sub N) ratios of 0.82-2.42, and very weak positive Eu anomalies (delta Eu = 1.2-1.6). The initial Sr isotopic compositions of the jadeitite range from 0.704000 to 0.703519 (t = 368 Ma), and the initial Nd-isotope ratios (epsilon (sub Nd) = +0.77 to +5.61) differ from those of ancient ocean water, oceanic sediments and eclogite, metagranite, and metasediments in the nearby Marun -Keu complex. Zircons from the jadeitite have variable REE contents (37-587 ppm) and are enriched in HREE, with La (sub CN) /Yb (sub CN) ratios ranging from 0.001 to 0.01, and Lu (sub CN) /Gd (sub CN) ratios ranging from 10 to 83. Cerium shows positive anomalies with Ce/Ce* values ranging from 2.8 to 72, and delta Eu from 0.53 to 1.02. The (super 176) Hf/ (super 177) Hf ratios of the zircons range from 0.282708 to 0.283017, with initial Hf isotope compositions ranging from 6.5 to 17.4. These characteristics resemble those of zircons from depleted mantle-derived magmas. The delta (super 18) O isotope compositions of the zircons range from 5.03 ppm to 6.04 ppm, with an averaged value of 5.45 + or - 0.11 ppm, similar to those of mantle rocks, suggesting that the zircons were acquired from precursor igneous rocks, and then transported and reworked by fluids from the subducting slab. Our new results show that the jadeitite was precipitated from material mainly produced by fluid interaction with mafic-ultramafic rocks in a subduction zone environment.


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: Pre-issue publication
Title: Jadeitite in the Syum-Keu ultramafic complex from Polar Urals, Russia; insights into fluid activity in subduction zones
Affiliation: Chinese Academy of Geological Sciences, Institute of Geology, Beijing, China
Published: 20160717
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Germany
References: 104
Accession Number: 2016-085308
Categories: Igneous and metamorphic petrologyIsotope geochemistry
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 7 tables, geol. sketch map
N67°19'60" - N67°40'00", E66°00'00" - E67°30'00"
Secondary Affiliation: National Cheng-Kung University, TWN, TaiwanRussian Academy of Sciences, Institute of Geology of Ore Deposits, Petrography, Mineralogy, RUS, Russian FederationRussian Academy of Sciences, Komi Science Center of Uralian Division, RUS, Russian FederationRussian Academy of Sciences, State Geological Museum,
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Schweizerbart'sche Verlagsbuchhandlung. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201641
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