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 δ¹⁸O values (5.39 ± 0.49‰, n = 27; 5.64 ± 0.48‰, n = 34; and 5.28 ± 0.34‰, 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 δ¹⁸O (mean of 6.50‰, 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 ɛHf(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 ¹⁷⁶Hf/¹⁷⁷Hf 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 ɛNd(t) = –1.5 ± 1.8) differ from the other rocks, which have relatively restricted ranges in initial ɛNd (mean ɛNd = 0.9 ± 0.2). The major set of ɛNd values around 1.0 at Talnakh is attributed to limited crustal contamination, presumably in deep magma chambers, whereas the smaller set of negative ɛNd values in taxitic-textured rocks is consistent with greater involvement of a crustal component and reflects an interaction with the wall rocks during emplacement.

中文翻译：

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氧-af-钕同位素对塔尔纳克超镁铁质-镁铁质侵入岩起源的约束（俄罗斯诺里尔斯克省）

诺里尔斯克省（俄罗斯）的超镁铁质-镁铁质Talnakh侵入岩带是世界上主要的铂族元素（PGE）-Cu-Ni硫化物矿床之一。这项研究采用了多种技术方法，包括对锆石的原位Hf-O同位素分析与全岩Nd同位素数据相结合，以便获得对Talnakh经济入侵成因的新见解。从gabbrodiorite锆石，层状系列的辉长岩，以及超基性岩具有相似的地幔状平均δ ^18个O值（5.39±0.49‰，N = 27; 5.64±0.48‰，N = 34;和5.28±0.34‰，正分别等于7），这与塔尔纳克入侵的母岩浆来自地幔的起源一致。与此相反，从侵入的基部硫化物承载taxitic纹理化橄长岩具有高δ ¹⁸O（平均值为6.50‰，n = 3），表明地壳成分可能在含硫化物的岩溶质构筑岩石形成过程中参与。来自塔尔纳赫侵入岩不同岩石的锆石的Hf同位素组成显示出显着变化，辉长岩的ɛHf（t）值范围从–3.2至9.8，非矿化层序辉长岩的ɛHf（t）值从–4.3至11.6，而矿化的层序辉长岩则从2.3至12矿化的超镁铁质岩石，以及在侵入体底部的矿化的盐渍化纹理岩石从–3.5到8.8。初始¹⁷⁶ Hf / ¹⁷⁷的有效范围Hf值归因于Talnakh侵入岩形成过程中不同岩浆源的相互作用。这些包括（1）相当于枯竭地幔的幼年源；（2）次大陆岩石圈源；以及（3）次要地壳成分。侵入岩基底部成矿化的盐岩化岩石的初始全岩Nd同位素组成（平均ɛNd（t）= –1.5±1.8）与其他岩石不同，其他岩石的初始ɛNd范围相对有限（平均ɛNd= 0.9±0.2）。塔尔纳克（Talnakh）的主要ɛNd值大约为1.0，这归因于地壳污染有限，大概是在深部岩浆室内，而在滑行构造岩石中较小的ɛNd负值集与地壳成分的更大参与一致，并反映了安置期间围墙晃动。