The Archean Legris Lake mafic–ultramafic complex (LLC) is spatially (~ 12 km east) and temporally (2690.59 ± 0.77 Ma) associated with the world-class Lac des Iles (LDI) palladium deposit. Modeling of whole-rock major-element compositions suggests that this complex, previously interpreted as gabbroic, is gabbronoritic in composition, adding to the likely association between LDI and the LLC. Mantle normalized trace-element profiles and modeled parental melt compositions from the cumulate lithologies indicate initial melt extraction from a metasomatized mantle source in an arc setting and subsequent crystallization of olivine, orthopyroxene, and plagioclase at depth following assimilation of SiO₂ and S from tonalitic country rock. External S assimilation contributed to sulfide saturation at depth prior to or during emplacement, but sulfide melt entrainment in intruding magmas and its retention at the site of emplacement was variable. These interpretations are supported by (1) variations in Cu/Pd ratios between PGE-rich and PGE-poor lithologies, (2) the strongly negative Eu/Eu* of paragenetically early lithologies, (3) the overlap between whole-rock εNd_(T) values of LLC lithologies and Wabigoon tonalite, and (4) the positive δ³⁴S and uniformly non-zero ∆³³S values of magmatic sulfides. During emplacement the intruding melts also assimilated metasedimentary country rock. This effect likely became more pervasive during later stages and resulted in additional melt fractionation and inheritance of the trace-element signature of the metasedimentary country rock by the intruding magmas. This assimilation does not, however, seem to have been an important driver of sulfide saturation in this system.

太古代勒格里湖镁铁质-超镁铁质复合体 (LLC) 在空间上（以东约 12 公里）和时间上（2690.59 ± 0.77 Ma）与世界级的 Lac des Iles (LDI) 钯矿床有关。对全岩主要元素成分的模拟表明，这种以前被解释为辉长岩的复合体的成分是辉长岩，这增加了 LDI 和 LLC 之间的可能联系。地幔归一化的微量元素剖面和来自堆积岩性的模拟母体熔体成分表明，在弧环境中从交代地幔源中初始熔体提取，以及随后同化 SiO 2 后在深处橄榄石、斜方辉石和斜长石的_结晶S 则来自调性乡村摇滚。外部硫同化有助于在侵位之前或侵位过程中深度处的硫化物饱和，但侵入岩浆中的硫化物熔体夹带及其在侵位地点的保留是可变的。这些解释得到以下支持：(1) 富含 PGE 和贫 PGE 岩性之间 Cu/Pd 比率的变化，(2) 共生早期岩性的强负 Eu/Eu*，(3) 全岩 εNd 之间的重叠_{（ T)} LLC 岩性和 Wabigoon 英云闪岩的值，以及 (4) 正 δ ³⁴ S 和一致非零 Δ ³³岩浆硫化物的S值。在侵位过程中，侵入的熔体也同化了变沉积围岩。这种效应可能在后期变得更加普遍，并导致侵入岩浆导致额外的熔体分馏和变沉积围岩的微量元素特征的继承。然而，这种同化似乎并不是该系统中硫化物饱和的重要驱动因素。