Abstract

New results on the study of the geochemical and Sr–Nd isotopic compositions of effusive and explosive rocks of the Oxfordian–Kimmeridgian Kulpolnei complex and dikes intruding this complex, located in the northwestern part of the South Anyui suture are presented. It is established that effusive and explosive rocks were formed within an intraoceanic convergent boundary (back-arc basin and/or island arc). The volcanics of the Kulpolnei complex are intruded by diorite and plagiogranite dikes, which are deformed together with the host rocks. The concordant U–Th–Pb (SIMS) ages of zircons from dikes are 143 ± 1 to 140 ± 1 Ma. The similarity between the geochemical compositions of volcanics and dikes suggests these units had formed in the same geodynamic setting. If this assumption is correct, the upper age limit of suprasubduction volcanism can be considered to be significantly younger, up until the Berriasian age.

中文翻译：

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南安伊缝合带（西楚科奇）库尔波尔内火山杂岩：组成、时代和古构造解释

摘要

介绍了对位于南安伊缝合线西北部的牛津阶-基默里吉阶 Kulpolnei 杂岩体和侵入该杂岩体的岩脉的喷流岩和爆炸岩的地球化学和 Sr-Nd 同位素组成的研究的新结果。已确定在洋内会聚边界（弧后盆地和/或岛弧）内形成了溢流和爆炸性岩石。Kulpolnei 杂岩体的火山岩被闪长岩和斜长花岗岩岩脉侵入，它们与主岩一起变形。岩脉锆石的一致 U-Th-Pb (SIMS) 年龄为 143 ± 1 至 140 ± 1 Ma。火山岩和岩脉的地球化学成分之间的相似性表明这些单元是在相同的地球动力学环境中形成的。如果这个假设是正确的，