The ∼ 1.15-billion-year-old (Ga) Premier kimberlite pipe (Cullinan diamond mine), South Africa, is composed of several distinct kimberlite facies (Grey, Brown, Pale Piebald, Dark Piebald, Black Coherent [Type 3C], Blue/Brown Transitional, and Fawn). We report bulk rock Re-Os isotope data for Premier kimberlite facies, as well as for a suite of entrained peridotite and mafic xenoliths. These data are complemented by bulk rock highly siderophile element (HSE: Re, Pd, Pt, Ru, Ir, Os), major- and trace-element abundances. Measured 187Os/188Os for the kimberlite facies range from 0.1223 to 0.1672 (γOsi of −2.5 to + 17.4), peridotite xenoliths range from 0.1096 to 0.1244 (γOsi of −13.3 to −1.1), and pyroxenite xenoliths range from 0.1796 to 0.938 (γOsi of + 27 to + 419). A single measured amphibolite xenolith has the most radiogenic measured 187Os/188Os of 2.86 (γOsi of + 43). Harzburgite xenoliths yield time of rhenium depletion model ages (TRD) of ∼ 1.5 to 2.8 Ga, consistent with average TRD ages for Premier peridotites (2.4 ± 0.4 Ga). With these and published data, we considered the relationships between kimberlite and mantle xenoliths, compare estimates of relative peridotite incorporation to sampled diamond grade, and explore recratonization versus refertilization arguments with regards to TRD model ages. Kimberlite melt infiltration into Premier peridotite xenoliths is evident from melt veins accounting for ∼ 2 and ∼ 14 modal % of samples, and has led to incompatible element enrichment, including elevated Re. In turn, kimberlites show geochemical evidence for addition of peridotite xenolith fragments, with Type 3C having > 30 % more peridotite contribution than the Brown volcaniclastic facies. Kimberlites and peridotites plot on a 187Re/188Os versus 187Os/188Os mixing line (R2 = 0.92), with kimberlites having older apparent ages than the true age of crystallization. This mixing line provides estimates of lithospheric incorporation into the kimberlites, where the units with higher peridotite incorporation do not correlate with diamond grade. This is likely due to lithological and post-emplacement alteration heterogeneity within the kimberlite units, perhaps also reflecting the eclogitic paragenesis of many Premier diamonds. The peridotites provide evidence for the nature of the lithosphere beneath Premier prior to ∼ 1.15 Ga. Metasomatism of the peridotites is possibly linked to the Bushveld Igneous Event at ∼ 2 Ga, as well as to other magmatic events that affected the Kaapvaal craton from the Archean to the Mesoproterozoic. Premier peridotites do not suggest that the cratonic lithosphere beneath the region was completely replaced. Samples with Proterozoic TRD eruption model ages may represent Archean lithosphere that experienced alteration by metasomatism and modification, such as during the Bushveld Igneous Event.

中文翻译：

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金刚石金伯利岩熔体-地幔相互作用的 187Re-187Os 和高嗜铁元素元素研究以及大陆岩石圈的推断年龄


南非 11.5 亿年前 （Ga） 的一级金伯利岩管（库利南钻石矿）由几个不同的金伯利岩相（灰色、棕色、浅斑秃、深色斑秃、黑色相干 [3C 型]、蓝色/棕色过渡岩和小鹿岩）组成。我们报告了主要金伯利岩相以及一组夹带橄榄岩和镁铁质异石的块状岩石 Re-Os 同位素数据。这些数据由块状岩石高度嗜铁元素 （HSE： Re， Pd， Pt， Ru， Ir， Os） 以及主量和微量元素丰度补充。金伯利岩相的测量 187Os/188Os 范围为 0.1223 至 0.1672（γOsi 为 -2.5 至 + 17.4），橄榄岩异石范围为 0.1096 至 0.1244（γOsi 为 -13.3 至 -1.1），辉石石种岩范围为 0.1796 至 0.938（γOsi 为 + 27 至 + 419）。单个测量的角闪石异石具有最放射性的测量 187Os/188Os，为 2.86（γOsi 为 + 43）。哈茨堡石异石的铼耗尽模型年龄 （TRD） 的产量时间 （TRD） 约为 ∼ 1.5 至 2.8 Ga，与主要橄榄岩的平均 TRD 年龄 （2.4 ± 0.4 Ga） 一致。利用这些数据和已发表的数据，我们考虑了金伯利岩和地幔异石之间的关系，将橄榄岩相对掺入的估计值与采样钻石等级进行比较，并探讨了关于 TRD 模型年龄的重新着色与再受精的争论。金伯利岩熔融渗透到主要橄榄岩异石中，从占样品 ∼ 2 和 ∼ 14 模态百分比的熔体矿脉中可以明显看出，并导致不相容的元素富集，包括升高的 Re。反过来，金伯利岩显示出橄榄岩异石碎片的地球化学证据，其中 3C 型的橄榄岩贡献比棕色火山碎屑相多 30%。 金伯利岩和橄榄岩在 187Re/188Os 与 187Os/188Os 混合线上绘图 （R2 = 0.92），金伯利岩的表观年龄比实际结晶年龄早。该混合线提供了岩石圈掺入金伯利岩的估计值，其中橄榄岩掺入量较高的单元与钻石品位无关。这可能是由于金伯利岩单元内的岩性和埋地后蚀变异质性，也可能反映了许多 Premier 钻石的榴辉共生。橄榄岩为 ∼ 1.15 Ga之前 Premier 下方岩石圈的性质提供了证据。橄榄岩的交代作用可能与 ∼ 2 Ga的灌木丛火成岩事件有关，以及影响从太古代到中元古代的 Kaapvaal 克拉通的其他岩浆事件。主要橄榄岩并不表明该地区下方的克拉通岩石圈被完全取代。具有元古代 TRD 喷发模型年龄的样品可能代表太古代岩石圈，该岩石圈经历了交代作用和修饰的改变，例如在布什维尔德火成岩事件期间。