Feldspathic lherzolite and harzburgite are reported here for the first time in the southern Lac des Iles Complex; an ~ 2.69-Ga arcuate mafic intrusion that hosts world-class Pd mineralization within varitextured and brecciated gabbronoritic rocks. The olivine-bearing rocks (Mg#_75.9–80.8) are medium- to coarse-grained, weakly to strongly serpentinized, and bordered by variably altered norite. They possess relatively high Al₂O₃ contents (4.8–10.3 wt.%), pronounced negative Nb/Nb* (0.07–0.25) values, flat to shallow negatively sloping REE profiles (La/Yb_N 1.3–4.4), and variable Eu/Eu* (0.4–1.6) values. Weakly altered samples comprise subhedral olivine (Fo_78.6–81.8) with polymineralic melt inclusions and peritectic orthopyroxene rims, cumulus orthopyroxene, sub-poikilitic clinopyroxene, as well as plastically deformed and clustered plagioclase crystals. With increasing degrees of alteration, olivine is variably serpentinized or pseudomorphically replaced by an assemblage of talc, carbonate, magnetite, and Fe-sulfides. Sparsely disseminated pentlandite-chalcopyrite-pyrrhotite (± sphalerite) blebs with platinum-group minerals (zvyagintsevite, kotulskite, and sperrylite) are rare and commonly partially replaced by magnetite. Nickel concentrations are primarily controlled by olivine (1900–4200 ppm Ni), as supported by a positive correlation between whole-rock MgO and Ni contents. Sulfur, Cu, Pd, and Pt show positive correlations and Pd/Pt values range from 2.6 to 6.7. The whole-rock and mineral compositions can be replicated through the modeling of batch crystallization of a hydrous andesitic magma that has interacted with antecedent feldspathic cumulates. The parent magma was likely at or close to sulfide saturation upon emplacement and may have co-existed with a volatile-rich phase. The Lac des Iles Complex may serve as a type example of Archean continental arc-related magmatic sulfide deposits, fed by fertile andesitic parent magmas formed through the differentiation of primitive sub-arc mantle melts in the juvenile crust.

长石二辉橄榄石和方辉橄榄石首次在 Lac des Iles Complex 南部被发现；约 2.69-Ga 的弓形镁铁质侵入体，在各种纹理和角砾状辉长岩中蕴藏着世界级的钯矿化。含橄榄石的岩石 (Mg# _75.9–80.8 ) 为中到粗粒度，弱到强蛇纹石化，周围有不同程度的蚀变苏长岩。它们具有相对较高的 Al ₂ O ₃含量 (4.8–10.3 wt.%)、明显的负 Nb/Nb* (0.07–0.25) 值、平坦至浅的负倾斜 REE 分布 (La/Yb _N 1.3–4.4) 和可变的Eu/Eu* (0.4–1.6) 值。弱蚀变样品包括面状橄榄石（Fo _78.6-81.8），具有多矿物熔体包裹体和包晶斜方辉石边缘、积云斜方辉石、亚异斜长石斜长石以及塑性变形和簇状斜长石晶体。随着蚀变程度的增加，橄榄石不同程度地被蛇纹石化或被滑石、碳酸盐、磁铁矿和硫化铁的组合所取代。稀疏浸染的镍黄铁矿-黄铜矿-磁黄铁矿（±闪锌矿）气泡与铂族矿物（zvyagintsevite、kotulskite 和 sperrylite）非常罕见，通常部分被磁铁矿取代。镍浓度主要受橄榄石（1900–4200 ppm Ni）控制，全岩 MgO 和 Ni 含量之间的正相关性也证明了这一点。硫、铜、钯和铂呈现正相关，Pd/Pt 值范围为 2.6 至 6.7。通过对与先前长石堆积物相互作用的含水安山岩浆的批量结晶进行建模，可以复制整个岩石和矿物成分。母岩浆在就位时可能处于或接近硫化物饱和状态，并且可能与富含挥发物的相共存。 Lac des Iles 杂岩体可以作为与太古宙大陆弧相关的岩浆硫化物矿床的典型例子，其由新生地壳中原始弧下地幔熔体分异形成的肥沃的安山岩母岩浆供给。