In this paper, new main and trace elements and isotopic data are presented for 14 coarse-grained eclogite xenoliths from the V. Grib kimberlite pipe in the central part of the Arkhangelsk Diamondiferous Province. Based on reconstructed whole rock MgO content, this suite is divided into high-MgO and low-MgO varieties. Eclogitic groups have a similar range of variations in the trace element compositions of garnet, clinopyroxene and reconstructed whole rock. All eclogites show positive Eu anomalies in garnet and Sr anomalies in the whole rock. The negative correlation between the Mg#, Sr/Lu ratio and HREE in a whole rock points to upper and lower oceanic crustal rocks as a protolith for eclogites with high and low whole rock HREEs, respectively. Low-MgO eclogites with higher whole rock HREEs have the basaltic upper oceanic crustal protolith, whereas the protoliths of eclogites with lower whole rock HREEs could be of gabbroic composition from the lower oceanic crust. High-MgO eclogites could represent MgO-rich portions of oceanic crustal rocks: picritic/MgO basalt portions in the upper oceanic crust and troctolite portions in the lower oceanic crust. The Sr and Nd isotope compositions suggest a complex history of eclogites during their residence in the lithospheric mantle. Similarities in the Nd isotope compositions and two-point Sm-Nd isochron ages are evidence for re-equilibration of the Sm-Nd isotope system between the eclogite garnet and clinopyroxene via a pre-kimberlite thermal event at 396 ± 24 Ma. The subset of clinopyroxenes from four eclogites has a Sr isotope composition that plots on the isochron at an age of 2.84 Ga, which reflects the time of the subduction event and emplacement into the lithosphere and corresponds to the time of the Belomorian Eclogite Province of Baltic Shield formation.

中文翻译：

---

V. Grib 管榴辉岩的起源（俄罗斯西北部阿尔汉格尔斯克地区）：地球化学、Sm-Nd 和 Rb-Sr 同位素以及与区域前寒武纪构造的关系

本文提供了来自阿尔汉格尔斯克钻石矿省中部 V. Grib 金伯利岩管的 14 种粗粒榴辉岩包体的新的主元素和微量元素及同位素数据。根据重建的全岩MgO含量，该套件分为高MgO和低MgO品种。榴辉岩群在石榴石、单斜辉石和重建全岩的微量元素组成方面具有相似的变化范围。所有榴辉岩均在石榴石中显示出正 Eu 异常，在整个岩石中显示出 Sr 异常。全岩中Mg#、Sr/Lu比和HREE之间的负相关表明上、下洋壳岩石分别是具有高和低全岩HREE的榴辉岩的原岩。具有较高全岩 HREE 的低 MgO 榴辉岩具有玄武质上大洋地壳原岩，而具有较低全岩 HREE 的榴辉岩原岩可能是来自下洋地壳的辉长岩成分。高 MgO 榴辉岩可以代表大洋地壳岩石中富含 MgO 的部分：上大洋地壳中的苦素 / MgO 玄武岩部分和下大洋地壳中的皱褶长石部分。Sr 和 Nd 同位素组成表明榴辉岩在岩石圈地幔中停留期间的复杂历史。Nd 同位素组成和两点 Sm-Nd 等时年龄的相似性是榴辉岩石榴石和斜辉石之间 Sm-Nd 同位素系统通过 396 ± 24 Ma 前金伯利岩热事件重新平衡的证据。来自四种榴辉岩的单斜辉石子集具有 Sr 同位素组成，绘制在 2.84 Ga 年龄的等时线上，