The Yilgarn Craton and its northern margin contain a variety of petrogenetically poorly defined small-volume alkaline ultramafic rocks of Proterozoic age. This study documents the petrography, mineral and bulk-rock geochemistry and Nd-Hf-Sr-Pb isotope compositions of a selected suite of these rocks. They comprise ~2.03–2.06 Ga ultramafic lamprophyres (UML) and carbonatites from the Eastern Goldfields Superterrane (EGS), ~0.86 Ga UML from Norseman, and orangeites from the Earaheedy Basin, including samples from Jewill (~1.3 Ga), Bulljah (~1.4 Ga) and Nabberu (~1.8–1.9 Ga). The Proterozoic UML and carbonatites from the EGS and Norseman display very consistent chondritic to superchondritic Nd-Hf isotope compositions and trace-element ratios similar to modern OIBs, which are indicative of a common mantle source across this wide alkaline province. These Nd-Hf isotope compositions overlap with the evolution trends of global kimberlites through time, thus suggesting that this mantle source could be deep and ancient as that proposed for kimberlites. Conversely, the orangeites located in the Earaheedy Basin along the northern margin of the Yilgarn Craton display trace element signatures similar to subduction-related calc-alkaline magmas. Taken together with their highly enriched Sr-Nd-Hf isotope compositions, these characteristics indicate an ancient lithospheric mantle source, which was probably metasomatised by subduction-related fluids. As the ages of the Bulljah and Jewill orangeites overlap with the breakup of the Columbia supercontinent, it is proposed that orangeite magmatism was triggered by changes in plate stress conditions associated with this event. This study provides a comprehensive picture of the genesis of Proterozoic alkaline magmatism in the Yilgarn Craton, highlighting the complex tectono-magmatic evolution of this lithospheric block after its assembly in the Archean.

Yilgarn Craton及其北缘包含各种古生代时代定义不明确的小体积碱性超镁铁质岩石。这项研究记录了这些岩石的精选套件的岩石学，矿物和块状岩石地球化学以及Nd-Hf-Sr-Pb同位素组成。它们包括〜2.03–2.06 Ga超镁铁质煌斑岩（UML）和来自东部金田超地层（EGS）的碳酸盐岩，〜0.86 Ga UML来自诺斯曼的岩盐岩以及来自Earaheedy盆地的橘红色岩岩，包括来自Jewill（〜1.3 Ga），Bulljah（〜 1.4 Ga）和Nabberu（〜1.8–1.9 Ga）。来自EGS和Norseman的元古代UML和碳酸盐岩显示出与现代OIB相似的软骨至超软骨碎屑Nd-Hf同位素组成和痕量元素比，这表明在整个宽碱性省都有常见的地幔来源。这些Nd-Hf同位素组成与全球金伯利岩的演化趋势重叠，因此表明该地幔源可能像金伯利岩所建议的那样深而古老。相反，位于伊亚尔格克拉通北部边缘的厄亚希迪盆地的橘子岩显示出与俯冲相关的钙碱性岩浆相似的痕量元素特征。这些特征连同其高度富集的Sr-Nd-Hf同位素组成一起，显示出古老的岩石圈地幔源，可能是与俯冲相关的流体交代的。由于Bulljah和Jewill橙岩的年龄与哥伦比亚超大陆的破裂重叠，因此有人认为，与该事件相关的板应力条件的变化触发了橙岩岩浆作用。