The Kharbei Amphibolite–Gneiss Complex (Polar Urals): P–T Evolution and Results of U–Pb LA-ICP-MS Isotopic Study of Metamorphic Zircon

IF 0.7 4区地球科学 Q4 GEOSCIENCES, MULTIDISCIPLINARY

Doklady Earth Sciences Pub Date : 2024-07-01 DOI:10.1134/s1028334x24602761

N. S. Ulyasheva, A. S. Shuyskiy, V. B. Khubanov

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Abstract

In the study of the Khanmeikhoi Formation of the central zone of the Kharbei amphibolite–gneiss complex, it was shown that the amphibolites, schists, and plagiogneisses common here form two primary igneous series: low-alumina tholeiitic metabasalts of normal alkalinity and a differentiated series of high-alumina rocks from metatrachybasalts to metarhyolites with high alkalinity. According to the zoning of garnets, progressive and regressive branches of metamorphism are recorded, the peak conditions of which, according to calculations using the winTWQ program, correspond to the high-temperature stage of the amphibolite facies at high pressures (T = 690–750°C, P = 8.1–9.4 kbar). For the first time, metamorphic zircon from Grt-Bi plagiogneiss with low Th/U ratios of 0.01–0.04 and weakly expressed positive cerium (Ce/Ce* = 1.4–1.7) and negative europium (Eu/Eu* = 0.7–0.9) has been identified in the anomalies, the age of which, according to the results of the U–Pb LA-ICP-MS isotope method, is estimated to be Early Carboniferous (359–341 Ma). This time apparently characterizes the transition from the peak of metamorphism to the regressive stage associated with the exhumation of rocks. The results obtained indicate the formation of the Kharbei amphibolite–gneiss complex during the formation of the Ural orogen and allow us to consider it as an indicator of Paleozoic collision processes.

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哈尔贝闪长岩-片麻岩复合体（极地乌拉尔）：变质锆石的 P-T 演变和 U-Pb LA-ICP-MS 同位素研究结果

摘要在对哈尔贝闪长岩-片麻岩复合体中心地带的汗梅霍伊地层的研究中，发现这里常见的闪长岩、片岩和长片麻岩形成了两个原生火成岩系列：正常碱度的低铝透辉石变质岩和从偏闪长岩到高碱度偏闪长岩的高铝岩石分异系列。根据石榴石的分带，记录了变质作用的渐进和退行分支，根据 winTWQ 程序的计算，其峰值条件对应于高温高压（T = 690-750°C，P = 8.1-9.4 千巴）下的闪长岩面的高温阶段。根据 U-Pb LA-ICP-MS 同位素方法的结果，该异常的年龄估计为早石炭纪（359-341Ma）。这一时期显然是变质作用高峰期向与岩石掘出有关的回归阶段过渡的时期。研究结果表明，哈尔贝闪长岩-片麻岩复合体是在乌拉尔造山带形成过程中形成的，因此我们可以将其视为古生代碰撞过程的一个指标。

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来源期刊

Doklady Earth Sciences 地学-地球科学综合

CiteScore

1.40

自引率

22.20%

发文量

138

审稿时长

3-6 weeks

期刊介绍： Doklady Earth Sciences is a journal that publishes new research in Earth science of great significance. Initially the journal was a forum of the Russian Academy of Science and published only best contributions from Russia. Now the journal welcomes submissions from any country in the English or Russian language. Every manuscript must be recommended by Russian or foreign members of the Russian Academy of Sciences.