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Oxygen-hafnium-neodymium isotope constraints on the origin of the Talnakh ultramafic-mafic intrusion (Norilsk Province, Russia)

Kreshimir N. Malitch, Elena A. Belousova, William L. Griffin, Laure Martin, Inna Yu. Badanina and Sergey F. Sluzhenikin
Oxygen-hafnium-neodymium isotope constraints on the origin of the Talnakh ultramafic-mafic intrusion (Norilsk Province, Russia)
Economic Geology and the Bulletin of the Society of Economic Geologists (June 2020) 115 (6): 1195-1212

Abstract

The ultramafic-mafic Talnakh intrusion in the Norilsk province (Russia) hosts one of the world's major platinum group element (PGE)-Cu-Ni sulfide deposits. This study employed a multitechnique approach, including in situ Hf-O isotope analyses of zircon combined with whole-rock Nd isotope data, in order to gain new insights into genesis of the Talnakh economic intrusion. Zircons from gabbrodiorite, gabbroic rocks of the layered series, and ultramafic rocks have similar mantle-like mean delta (super 18) O values (5.39 + or - 0.49 ppm, n = 27; 5.64 + or - 0.48 ppm, n = 34; and 5.28 + or - 0.34 ppm, n = 7, respectively), consistent with a mantle-derived origin for the primary magma(s) parental to the Talnakh intrusion. In contrast, a sulfide-bearing taxitic-textured troctolite from the basal part of intrusion has high delta (super 18) O (mean of 6.50 ppm, n = 3), indicating the possible involvement of a crustal component during the formation of sulfide-bearing taxitic-textured rocks. The Hf isotope compositions of zircon from different rocks of the Talnakh intrusion show significant variations, with epsilon Hf(t) values ranging from -3.2 to 9.8 for gabbrodiorite, from -4.3 to 11.6 for unmineralized layered-sequence gabbroic rocks, from 2.3 to 12 for mineralized ultramafic rocks, and from -3.5 to 8.8 for mineralized taxitic-textured rocks at the base of the intrusion. The significant range in the initial (super 176) Hf/ (super 177) Hf values is ascribed to interaction of distinct magma sources during formation of the Talnakh intrusion. These include (1) a juvenile source equivalent to the depleted mantle, (2) a subcontinental lithospheric source, and (3) a minor crustal component. Initial whole-rock Nd isotope compositions of the mineralized taxitic-textured rocks from the base of the intrusion (mean epsilon Nd(t) = -1.5 + or - 1.8) differ from the other rocks, which have relatively restricted ranges in initial epsilon Nd (mean epsilon Nd = 0.9 + or - 0.2). The major set of epsilon Nd values around 1.0 at Talnakh is attributed to limited crustal contamination, presumably in deep magma chambers, whereas the smaller set of negative epsilon Nd values in taxitic-textured rocks is consistent with greater involvement of a crustal component and reflects an interaction with the wall rocks during emplacement.


ISSN: 0361-0128
EISSN: 1554-0774
Coden: ECGLAL
Serial Title: Economic Geology and the Bulletin of the Society of Economic Geologists
Serial Volume: 115
Serial Issue: 6
Title: Oxygen-hafnium-neodymium isotope constraints on the origin of the Talnakh ultramafic-mafic intrusion (Norilsk Province, Russia)
Affiliation: Russian Academy of Sciences, Ural Branch, A. N. Zavaritsky Institute of Geology and Geochemistry, Ekaterinburg, Russian Federation
Pages: 1195-1212
Published: 20200624
Text Language: English
Publisher: Economic Geology Publishing Company, Lancaster, PA, United States
References: 148
Accession Number: 2020-051337
Categories: Economic geology, geology of ore depositsIsotope geochemistry
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sects., strat. col., 2 tables, geol. sketch maps
N69°33'03" - N69°33'04", E88°29'38" - E88°29'39"
Secondary Affiliation: Macquarie University, Department of Earth and Planetary Sciences, Centre of Excellence for Core to Crust Fluid Systems and Geochemical Evolution and Metallogeny of Continents, AUS, AustraliaUniversity of Western Australia, Centre for Microscopy Characterisation and Analysis, AUS, AustraliaRussian Academy of Sciences, Institute of Geology of Ore Deposits, Petrography, Mineralogy, and Geochemistry, RUS, Russian Federation
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2020, American Geosciences Institute. Abstract, Copyright, Society of Economic Geologists. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 202031
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