The interaction between mafic-ultramafic magma and crustal sulfide is considered a key process in the formation of magmatic Ni-Cu-platinum group element (PGE) sulfide deposits. Integrated S/Se and multiple sulfur isotope studies are the most robust in constraining the role of crustal sulfur during ore genesis. In the present study, we report the first integrated S/Se and multiple sulfur isotope study of magmatic sulfide occurrences in the Labrador Trough, namely, on the recently discovered Idefix PGE-Cu and Huckleberry Cu-Ni-(PGE) prospects.Whole-rock and in situ S/Se values (~810–3115) of magmatic sulfides and their host rocks are consistent with S loss during postmagmatic hydrothermal alteration, negating their use in interpreting the origin of S. Values of ∆³³S ~0 indicate no record of the assimilation of Archaean sulfur. Disseminated (–0.5 to +2.5‰) and globular (3.0–4.5‰) sulfides at Idefix as well as globular sulfides (2.1–9.6‰) at Huckleberry have δ³⁴S values greater than the accepted mantle range, suggesting that crustal S played a role in the formation of these sulfides. In contrast, disseminated and net-textured sulfides at Huckleberry have variable δ³⁴S values (–4.6 to +3.2‰) that are mostly within the accepted mantle range, excluding one anomalous sample that records relatively higher δ³⁴S values (11.9–15.0‰). It is proposed that sulfide melt segregated in response to the addition of small proportions of crustal S prior to the final emplacement of the host intrusions, i.e., in a feeder conduit or staging chamber. Isotopic exchange between the sulfide melt and silicate magma has diluted and, in places, eradicated a crustal δ³⁴S signature.

中文翻译：

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魁北克北部拉布拉多海槽中岩浆硫化物的原位多硫同位素和 S/Se 组成

镁铁质-超镁铁质岩浆与地壳硫化物的相互作用被认为是岩浆镍铜铂族元素（PGE）硫化物矿床形成的关键过程。综合 S/Se 和多种硫同位素研究在限制地壳硫在矿石成因过程中的作用方面最为有效。在本研究中，我们报告了对拉布拉多海槽岩浆硫化物矿点的首次综合 S/Se 和多种硫同位素研究，即最近发现的 Idefix PGE-Cu 和 Huckleberry Cu-Ni-(PGE) 前景。岩浆硫化物及其主岩的岩石和原位 S/Se 值 (~810–3115) 与岩浆后热液蚀变过程中 S 的损失一致，否定了它们在解释 S 起源中的用途。 Δ ^{33 的}值S ~0 表示没有太古代硫同化的记录。Idefix 的播散 (–0.5 至 +2.5‰) 和球状 (3.0–4.5‰) 硫化物以及 Huckleberry 的球状硫化物 (2.1–9.6‰) 的 δ ³⁴ S 值大于公认的地幔范围，表明地壳 S 发挥了作用在这些硫化物的形成中起作用。相比之下，哈克贝利的播散和网状硫化物具有可变的 δ ³⁴ S 值（–4.6 至 +3.2‰），大部分在可接受的地幔范围内，不包括记录相对较高 δ ^{34 的}异常样本S 值 (11.9–15.0‰)。有人提出，在主体侵入体的最终侵位之前，即在馈送管道或分段室中，硫化物熔体因添加小比例的地壳硫而发生分离。硫化物熔体和硅酸盐岩浆之间的同位素交换已经稀释，并在某些地方消除了地壳 δ ³⁴ S 特征。