Abstract

The paper presents new geological, petrological, and geochemical data on the dunite–clinopyroxenite–gabbro massifs of the Tamanvayam area. The time of formation of the intrusions is specified using U–Pb zircon dating. The Machevna Massif is mainly composed of gabbroids and clinopyroxenites, which are related by gradual facies transitions and intruded by amphibole gabbro, leucogabbro, and monzogabbro. The youngest rocks, cutting across all of the above-described varieties, are granites and granodiorites (tonalites), which make up composite injection bodies and small stocks in the central part of the massif. According to the new U–Pb dates, all of the intrusive rocks of the Machevna and Poputny intrusions were formed in a narrow time range of 73.1–67.7 Ma. The obtained range overlaps the formation interval of the siliceous volcanogenic sequences of the Achaivayam Formation (biostratigraphic studies, retrospective data). The geochemical similarity of the gabbroids and pyroxenites with intersecting amphibole gabbros and leuco- and monzogabbros allows us to attribute them to a single magmatic complex. The geochemical affinity and the penecontemporaneous formation of the intrusive rocks of the Tamanvayam area and volcanics of the Achaivayam Formation indicate their formation during a single tectonomagmatic event. At the same time, the gabbroids and pyroxenites can be considered as comagmatic rocks of the basalts and picrobasalts of the Achaivayam Formation. The high-Ca picrobasalts of the Achaivayam Formation that developed near the Machevna intrusion were presumably derived from parental melts of concentrically zonal massifs.

中文翻译：

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Tamanvayam组（Koryak–Kamchatka辫状带）的同心带地块：结构，年龄，岩石学和地球化学方面

摘要

本文介绍了Tamanvayam地区的辉长岩-辉绿岩-辉长岩断块的新的地质，岩石和地球化学数据。侵入的形成时间使用U–Pb锆石测年确定。马切夫纳地块主要由辉长岩和斜辉石组成，它们与逐渐的相变有关，并被闪闪发光的辉长岩，​​leucogabbro和monzogabbro侵入。分布在上述所有品种中的最年轻的岩石是花岗岩和花岗闪长岩（tonalite），它们组成了地层中部的复合注入体和少量储层。根据新的U–Pb年代，Machevna和Poputny侵入体的所有侵入岩都是在73.1–67.7 Ma的狭窄时间范围内形成的。所获得的范围与阿瓦瓦耶姆组硅质火山作用序列的形成间隔重叠（生物地层学研究，回顾性数据）。辉长岩和辉石岩与相交的角闪石辉长岩，无色和单生辉闪石的地球化学相似性使我们可以将它们归因于单个岩浆复合体。Tamanvayam地区侵入岩和Achaivayam组火山的地球化学亲和力和准同时期形成表明它们是在一次构造岩浆事件中形成的。同时，辉长岩和辉石岩也被认为是阿差瓦耶姆组玄武岩和微玄武岩的岩浆岩。