Аbstract

The basement of Arctic Alaska–Chukotka microcontinent (AAChM) is exposed in the Velitkenai granite–metamorphic dome of Chukotka. U–Th–Pb (SIMS) geochronological study of the orthogneisses of the basement, paragneisses after Paleozoic rocks, and leucogranites of the Velitkenai massif in the central and southwestern parts of this structure was carried out. The Neoproterozoic age of basement orthogneisses (Velitkenai complex) and the Albian age of granitoids of the last stage of the Velitkenai massif were confirmed. The latter coincides with the age of migmatization of orthogneisses. The youngest zircon populations from paragneisses within the Velitkenai complex are from the Cambrian and the Silurian; single zircon crystals contain inherited cores with ages of 1.7 and 1.9 Ga. The correlation of the Neoproterozoic orthogneisses of the Velitkenai granite–metamorphic dome with similar complexes of the other AAChM regions indicates the unity of its basement. It is suggested to enter the Velitkenai metamorphic complex into the legend of the Chukotka series of the third-generation geological map sheets.

中文翻译：

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以维利特克奈花岗岩-变质穹顶（俄罗斯东北部）为例的北极阿拉斯加-楚科奇微板块基底的年龄

摘要

北极阿拉斯加-楚科奇微大陆（AAChM）的基底暴露在楚科奇的韦利特克奈花岗岩变质穹顶中。对该构造中部和西南部的基底正片麻岩、古生代岩石后的副片麻岩以及维利特克奈地块的淡色花岗岩进行了U-Th-Pb（SIMS）年代学研究。确认了基底正片麻岩（Velitkenai 杂岩）的新元古代年龄和 Velitkenai 地块末期花岗岩的阿尔布阶时代。后者恰逢正片麻岩的混合化时代。Velitkenai 杂岩内的副片麻岩中最年轻的锆石群来自寒武系和志留系；单颗锆石晶体含有年龄为 1.7 和 1.9 Ga 的继承核心。Velitkenai 花岗岩-变质穹顶的新元古代正片麻岩与其他 AAChM 地区的类似杂岩的相关性表明其基底的统一性。建议将维利特克奈变质杂岩纳入第三代地质图张楚科奇系列的传说中。