Abstract

Zircon crystals from the alkaline and nepheline syenites of the Saharjok massif, which were formed during the magmatic (2645 ± 7 Ma), hydrothermal (1832 ± 7 Ma), and metamorphic (1784 ± 22 Ma) crystallization stages, were studied. Zircon from alkaline syenites displays lower εHf and εNd values than zircon from ocean island basalts (OIB); these values indicate their affinity to mantle-derived protoliths, which are similar to CHUR in isotope composition. It is assumed that the Neoarchean Keivy alkaline province formed as a result of the plume–lithosphere interaction, induced by the upwelling of a Neoarchean plume, which facilitated metasomatic alteration and the subsequent partial melting of rocks of the subcratonic lithospheric mantle and the crust. The parental melts of the Saharjok massif could have been formed during the resumption of plume activity 20–30 million years after alkaline granite emplacement in the province by the selective melting of the metasomatized lithospheric mantle rocks.

中文翻译：

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可乐半岛萨哈约克碱性地块Syenites锆石的Lu-Hf同位素组成

摘要

研究了Saharjok地块碱性和霞石正长岩中的锆石晶体，这些晶体是在岩浆（2645±7 Ma），热液（1832±7 Ma）和变质（1784±22 Ma）结晶阶段形成的。来自碱性正长岩的锆石比来自大岛玄武岩（OIB）的锆石显示出更低的εHf和εNd值；这些值表明它们与地幔衍生的原岩的亲和力，与同位素组成中的CHUR相似。据推测，新古纪基维碱性省是由于新古纪羽状流上升引起的羽流与岩圈相互作用而形成的，它促进了交代变质作用以及随后的克拉通岩石圈地幔和地壳的部分熔融。