ABSTRACT The Alpine Dyke Swarm (ADS), intruding Haast Schist in the Southern Alps, New Zealand, comprises dykes, sills and diatremes of alkaline and ultramafic lamprophyres, phonolites and carbonatites. Intrusion peaked at ∼25 Ma during inception of dextral transtensional displacement on the Alpine Fault plate boundary. In a chamber beneath Haast River, magmas evolved by fractional crystallisation from primitive lamprophyres to phonolites, and then by liquid immiscibility to carbonatite magmas. Carbonatitic magmas coexisted with a highly sodic fluid that metasomatised adjacent quartzofeldspathic schist to aegirine-albite fenites. Carbonatites fractionated from Ca- to Fe-rich and, under late-stage, hydrothermal conditions, to Ba-Sr-REE–rich varieties. Some lamprophyres rose directly from a highly refractory spinel- or possibly garnet-spinel peridotite mantle that had been extensively metasomatised prior to the low-degree partial melting event and Cr-diopside series nodule entrainment. Al-augite series nodules give ages similar to host lamprophyres and are interpreted as deep-seated cognate cumulates. Compared to the broadly coeval basaltic-basanitic magmas of the Dunedin Volcanic Group (DVG) of East Otago, ADS magmas are enriched in volatiles, LILE, and HFSE (including REE). DVG magmas were derived from a less metasomatised mantle source, and, although undergoing extensive fractionation, failed to achieve the extreme alkali enrichment necessary for silicate melt-carbonatite immiscibility.

中文翻译：

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新西兰高山堤群中板内碱性萤石-音沸石-碳酸岩组合的岩石学和成因

摘要 高山堤坝群 (ADS) 侵入新西兰南阿尔卑斯山的哈斯特片岩，由碱性和超镁铁质萤石、响岩和碳酸岩的堤坝、基石和硅藻土组成。在高山断层板块边界上的右旋张性位移开始期间，入侵达到峰值约 25 Ma。在哈斯特河下方的一个腔室中，岩浆通过从原始斑岩到响岩的分步结晶演化，然后通过液体不混溶演化为碳酸岩岩浆。碳酸质岩浆与高钠流体共存，该流体将相邻的石英长石片岩交代为灰钠长石粉岩。碳酸岩从富钙到富铁，在后期的热液条件下分馏为富 Ba-Sr-REE 品种。一些萤石直接从高度难熔的尖晶石或石榴石尖晶石橄榄岩地幔中升起，该地幔在低度部分熔融事件和 Cr-透辉石系列结核夹带之前已被广泛交代。Al-augite 系列结核的年龄与寄主萤火虫相似，被解释为深层次的同源堆积物。与东奥塔哥但尼丁火山群 (DVG) 广泛同时期的玄武质-玄武质岩浆相比，ADS 岩浆富含挥发物、LILE 和 HFSE（包括 REE）。DVG 岩浆来自交代较少的地幔源，尽管经历了广泛的分馏，但未能实现硅酸盐熔体-碳酸岩不混溶所需的极端碱富集。