Abstract Nickel (Ni) enrichment (>0.40 wt%) in olivine was previously recognized in mantle xenoliths and volcanic rocks. Though this enrichment is often attributed to subarc metasomatic processes, the occurrence of Ni rich olivines in mantle peridotites remains to be established. We found peridotites that randomly contain unusually high-Ni olivines (up to Ni = 0.53 wt%) from the mantle section of the Pujada Ophiolite, Philippines. The Pujada mantle peridotites can be classified into three groups based on their occurrence and spinel Cr#: Group I - massive lherzolites and harzburgites with Cr# =0.10-0.40, Group II - lherzolite-dunite and harzburgite-dunite interlayers with Cr# =0.10-0.40, and Group III - interlayered harzburgites and dunites with Cr# >0.40. Rare earth element composition of clinopyroxenes shows general light rare earth element (LREE) depletion and relatively flat heavy rare earth element (HREE) with minor LREE enrichment. The high-Ni olivines are associated to the occurrence of secondary orthopyroxenes, high modal abundance of orthopyroxenes (>30%) and LREE enrichment. The Ni enrichment in olivine is the result of the diffusion of Ni from a hybridized melt formed by the combination of pyroxenite melts, primitive MORB melt and siliceous slab-derived melts in a backarc setting. The crystallization of the hybridized melt shows the same case of formation for the high Ni-olivine phenocrysts in alkali basalts from Hawaii, Kamchatka and the Mexican Volcanic Belt.

中文翻译：

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菲律宾普贾达蛇绿岩中富镍橄榄石的非均质地幔橄榄岩的岩石成因

摘要 橄榄石中的镍 (Ni) 富集 (>0.40 wt%) 以前在地幔捕虏体和火山岩中被发现。尽管这种富集通常归因于弧下交代过程，但地幔橄榄岩中富镍橄榄石的存在仍有待确定。我们在菲律宾 Pujada 蛇绿岩的地幔部分发现了随机含有异常高镍橄榄石（高达 Ni = 0.53 wt%）的橄榄岩。Pujada 地幔橄榄岩可根据其产状和尖晶石 Cr# 分为三组：I 组 - Cr# =0.10-0.40 的块状二长橄榄岩和方辉橄榄岩，II 组 - Cr# =0.10 的二长橄榄岩和方辉橄榄岩夹层-0.40 和 III 组 - Cr# >0.40 的层状菱镁矿和纯辉石。单斜辉石的稀土元素组成显示出一般的轻稀土元素 (LREE) 贫化和相对平坦的重稀土元素 (HREE) 和少量的轻稀土元素富集。高镍橄榄石与次生斜方辉石的出现、斜方辉石的高模态丰度 (>30%) 和轻稀土元素富集有关。橄榄石中的镍富集是镍从辉石岩熔体、原始 MORB 熔体和硅质板片衍生熔体在弧后环境中结合形成的杂化熔体扩散的结果。混合熔体的结晶显示了夏威夷、堪察加和墨西哥火山带碱性玄武岩中高镍橄榄石斑晶的形成情况。高镍橄榄石与次生斜方辉石的出现、斜方辉石的高模态丰度 (>30%) 和轻稀土元素富集有关。橄榄石中的镍富集是镍从辉石岩熔体、原始 MORB 熔体和硅质板片衍生熔体在弧后环境中结合形成的杂化熔体扩散的结果。混合熔体的结晶显示了夏威夷、堪察加和墨西哥火山带碱性玄武岩中高镍橄榄石斑晶的形成情况。高镍橄榄石与次生斜方辉石的出现、斜方辉石的高模态丰度 (>30%) 和轻稀土元素富集有关。橄榄石中的镍富集是镍从辉石岩熔体、原始 MORB 熔体和硅质板片衍生熔体在弧后环境中结合形成的杂化熔体扩散的结果。混合熔体的结晶显示了夏威夷、堪察加和墨西哥火山带碱性玄武岩中高镍橄榄石斑晶的形成情况。弧后环境中原始 MORB 熔体和硅质板坯熔体。混合熔体的结晶显示了夏威夷、堪察加和墨西哥火山带碱性玄武岩中高镍橄榄石斑晶的形成情况。弧后环境中原始 MORB 熔体和硅质板坯熔体。混合熔体的结晶显示了夏威夷、堪察加和墨西哥火山带碱性玄武岩中高镍橄榄石斑晶的形成情况。