Equilibrium nickel isotope fractionation in nickel sulfide minerals
Equilibrium nickel isotope fractionation in nickel sulfide minerals
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硫化镍矿物中的平衡镍同位素分馏
DOI：
10.1016/j.gca.2017.10.018
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发表时间：
2018
影响因子：
5
通讯作者：
Shi Yaolin
中科院分区：
文献类型：
--
作者：
Liu Shanqi;Li Yongbing;Ju Yiwen;Liu Jie;Liu Jianming;Shi Yaolin
镍是地球上的一种重要元素，也是地核中的主要元素，在许多地质和生物系统中起着重要作用。镍硫化物作为镍的重要汇，与岩浆体系中镍的迁移和岩浆硫化物矿床的成因演化密切相关。镍硫化物的镍同位素可作为岩浆作用和岩浆硫化物矿床演化的地球化学示踪剂。然而，硫化物的镍同位素分馏因子至今仍知之甚少，这给镍同位素在与硫化物有关的地质问题中的应用带来困难。本文采用第一性原理方法计算了多石英（Ni 3S 4）、菱石英（Ni 3S 2）、菱镁矿（NiS）、硫砷铅矿（Ni 9 S8）和硫砷铅矿（NiS 2）的Ni同位素分馏参数。这些矿物的60 Ni/58 Ni（103 ln β 60-58）的约化分配函数比大小顺序为：polydymite> heazlewoodite> millerite> godlevelite> vaesite。这些镍硫化物中的镍同位素分馏与平均Nisingle键S键长近似呈线性关系，与平均Nisingle键Ni键长呈显著负相关。此外，Fe/Ni比值的变化也会导致Ni同位素分馏，Fe取代Ni后，60 Ni/58 Ni的还原配分函数比降低。
Nickel is an important element on Earth, and a major element in the Earth's core, and plays important roles in many geological and biological systems. As an important sink of Ni, Ni sulfides are closely concerned with Ni migration in magma systems and the genesis and evolution of magmatic sulfide deposits. Ni isotopes of Ni sulfides may be a powerful geochemical tracer in magmatic processes and evolution of magmatic sulfide deposits. However Ni isotope fractionation factors of sulfides remain poorly known, which makes the applications of Ni isotopes to geological problems associated with sulfides difficult. In this study, the first-principles methods are used to compute Ni isotope fractionation parameters of polydymite (Ni 3 S 4), heazlewoodite (Ni 3 S 2), millerite (NiS), godlevskite (Ni 9 S 8) and vaesite (NiS 2). The reduced partition function ratios of 60 Ni/58 Ni (10 3 ln β 60–58) for these minerals decrease in the order of polydymite> heazlewoodite> millerite> godlevskite> vaesite. Ni isotope fractionations in these Ni sulfides show an approximately linear dependence on the average Nisingle bondS bond lengths, and have a significant negative correlation with the average Nisingle bondNi bond lengths. Furthermore, a change in Fe/Ni ratio can also lead to Ni isotope fractionation, and with substitution Fe for Ni, the reduced partition function ratios of 60 Ni/58 Ni decrease.