Abstract Zircon U-Pb and Lu-Hf isotope analyses along with whole-rock Sm-Nd isotope studies shed a light on distribution of the Paleoarchean crust in the Kursk block, Eastern Sarmatia. It has been revealed that this domain consists of two provinces with different crust ages: the Paleoarchean Kursk-Besedino granulite-gneiss domain (KBd) and the Mesoarchaean Mikhailovsky granite-greenstone area (Mgga). The KBd encompasses TTG orthogneisses and pelite, BIF, and mafic volcanics (sills) metamorphosed in the granulite facies. The orthogneiss protolith was formed ca 3.55 Ga (U-Pb SHRIMP data) from a juvenile source. In the metapelites, U-Pb detrital zircon ages cluster in three groups, 3535–3556, 3464–3472, and 3334–3384 Ma. The latter one suggests post-Middle Paleoarchean age of the protoliths deposition. Sm-Nd and Lu-Hf isotope characteristics of the volcanic-sedimentary rocks suggest the leading role of Paleoarchean crustal material in their protoliths. The age of metamorphic zircon is ca 2.8 Ga in all the KBd rocks. The Mgga consists of TTG and volcanic-sedimentary units. The ages of the TTG, felsic volcanics and metasediments fall in a narrow range of 2.96–3.12 Ga. They have juvenile isotope-geochemical characteristics (eNd(t) = +0.3 – + 4.0; eHf(t) = -0.3 – + 5.8) without any contribution of Paleoarchean crust. High-temperature 2.8 Ga-old metamorphism is not recorded in the Mgga. Pronounced differences in the age of crust-forming events in the KBd and Mgga indicate that these continental blocks had a different geological history, hence were distant from each other during most of the Archean Eon, probably up to 2.8 Ga. The Paleoproterozoic Trosnyanskaya intrusion in the Mgga bears signs of the KBd Paleoarchean crust. This suggests a collision of these Archean blocks with the Mesoarchean being thrust over the Paleoarchean rocks possibly at ca 2.8 Ga.

中文翻译：

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库尔斯克地块东萨尔马提亚埋藏的古太古代核心：U-Pb、Lu-Hf 和 Sm-Nd 同位素映射和古构造应用

摘要 锆石 U-Pb 和 Lu-Hf 同位素分析以及全岩 Sm-Nd 同位素研究揭示了东萨尔马提亚库尔斯克地块古太古代地壳的分布。研究表明，该域由两个地壳时代不同的省份组成：古太古代库尔斯克-贝塞迪诺麻粒岩-片麻岩域（KBd）和中太古代米哈伊洛夫斯基花岗岩-绿岩区（Mgga）。KBd 包括 TTG 正片麻岩和泥质岩、BIF 和在麻粒岩相变质的基性火山岩（窗台）。正方麻岩原岩由幼年来源形成约 3.55 Ga（U-Pb SHRIMP 数据）。在变泥质岩中，U-Pb 碎屑锆石年龄聚集成三组，分别为 3535-3556、3464-3472 和 3334-3384 Ma。后者表明原岩沉积的后中古太古代时代。火山沉积岩的 Sm-Nd 和 Lu-Hf 同位素特征表明古太古代地壳物质在其原岩中起主导作用。所有 KBd 岩石中变质锆石的年龄约为 2.8 Ga。Mgga 由 TTG 和火山沉积单元组成。TTG、长英质火山岩和变质沉积物的年龄在2.96-3.12 Ga的狭窄范围内。它们具有幼年同位素地球化学特征（eNd(t) = +0.3 – + 4.0；eHf(t) = -0.3 – + 5.8 ) 没有古太古代地壳的任何贡献。Mgga 中没有记录到 2.8 Ga 的高温变质作用。KBd 和 Mgga 地壳形成事件年龄的显着差异表明这些大陆块具有不同的地质历史，因此在太古代的大部分时间里彼此相距遥远，可能高达 2.8 Ga。Mgga 中的古元古代 Trosnyanskaya 侵入体带有 KBd 古太古代地壳的迹象。这表明这些太古代块体与可能在大约 2.8 Ga 处被推到古太古代岩石上的中太古代发生碰撞。