A suite of peridotite xenoliths from the Chidliak kimberlite province provides an ideal opportunity to assess the age of the mantle lithosphere beneath the eastern Hall Peninsula Block (EHPB) in southern Baffin Island, Nunavut and to provide constraints on the lithospheric architecture of this region. The new dataset comprises highly siderophile element (HSE) abundances and ReOs isotopic compositions for 32 peridotite xenoliths sampled from four Late Jurassic-Early Cretaceous kimberlite pipes (CH-1, -6, -7, and -44). These peridotites represent strongly depleted mantle residues, with bulk-rock and olivine chemistry denoting melt extraction extents of up to 40%. The vast majority of samples show PPGE (Pt and Pd) depletion relative to IPGE (Os, Ir, and Ru) ((Pt/Ir)_N: 0.10–0.96, median = 0.57; (Pd/Ir)_N: 0.03–0.79, median = 0.24), coupled with mostly unradiogenic Os isotopic compositions (¹⁸⁷Os/¹⁸⁸Os = 0.1084–0.1170). These peridotites display strong correlations between ¹⁸⁷Os/¹⁸⁸Os and melt depletion indicators (such as olivine Mg number and bulk-rock Al₂O₃, (Pd/Ir)_N), suggesting that an ancient (~2.8 Ga) melt depletion event governed the formation of the Chidliak lithosphere. The prominent mode of T_RD^erupt model ages at ca. 2.8 Ga matches the main crust-building ages of the EHPB, demonstrating temporal crust-mantle coupled in the Meso-Neoarchean. These ancient melt-depletion ages are present throughout the depth of the ~200 km thick lithospheric mantle column beneath Chidliak. The Meso-Neoarchean formation age of the EHPB mantle broadly coincides with the timing of stabilization of the lithospheric mantle beneath the Greenlandic portion of the North Atlantic Craton (NAC). This, along with the similarity in modal mineralogy, chemical composition and evolutionary history, indicates that the EHPB, southern Baffin Island was once contiguous with the Greenlandic NAC. The mantle lithosphere beneath both the EHPB and the NAC show a similar metasomatic history, modified by multiple pulses of metasomatism. These multiple metasomatic events combined to weaken and thin the lithospheric mantle, culminating in the formation of the Labrador Sea and Davis Strait separating the EHPB from the Greenlandic NAC in the Paleocene.

来自奇德里亚克金伯利岩省的一系列橄榄岩异岩体提供了一个理想的机会，可以评估努纳武特南部巴芬岛东部霍尔半岛地块（EHPB）下的地幔岩石圈的年龄，并对该地区的岩石圈结构提供限制。新的数据集包括从四个晚侏罗纪-早白垩纪金伯利岩管（CH-1，-6，-7和-44）采样的32个橄榄岩异岩的高度亲铁元素（HSE）丰度和Re Os同位素组成。这些橄榄岩代表着严重耗尽的地幔残留物，大块岩石和橄榄石化学表明熔体提取程度高达40％。相对于IPGE（Os，Ir和Ru）（（Pt / Ir）_N：0.10-0.96，中位数= 0.57；（Pd / Ir）_N：0.03-0.79，中位数= 0.24），加上大部分非放射源的Os同位素组成（¹⁸⁷ Os / ¹⁸⁸ Os = 0.1084-0.1170）。这些橄榄岩在¹⁸⁷ Os / ¹⁸⁸ Os和熔体耗竭指示剂（例如橄榄石Mg数和块状岩石Al ₂ O ₃，（Pd / Ir）_N）之间显示出很强的相关性，表明这是一个古老的（〜2.8 Ga）熔体耗竭事件控制了Chidliak岩石圈的形成。T _RD^爆发的突出模式模特年龄约。2.8 Ga与EHPB的主要地壳构造年龄相吻合，显示了中新新世时期的临时地幔幔。在Chidliak下方约200 km厚的岩石圈地幔柱的整个深度中都存在着这些古老的熔体耗尽时代。EHPB地幔的中新新世形成时代与北大西洋克拉通（NAC）格陵兰部分下方岩石圈地幔稳定的时间大致吻合。这与模态矿物学，化学成分和演化史的相似性一起表明，巴芬岛南部的EHPB曾经与格陵兰NAC相邻。EHPB和NAC下方的地幔岩石圈显示出相似的交代史，并被多次交代作用所修饰。