Basalts of the Riphean Sequences of the Bashkirian Meganticlinorium, South Urals: New 147Sm‒143Nd and Rb‒Sr ID-TIMS Isotopic Constraints

IF 0.7 4区地球科学 Q4 GEOSCIENCES, MULTIDISCIPLINARY

Doklady Earth Sciences Pub Date : 2024-06-20 DOI:10.1134/s1028334x24602372

V. N. Puchkov, Yu. L. Ronkin, N. D. Sergeeva

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Abstract

The first results of ¹⁴⁷Sm‒¹⁴³Nd and Rb‒Sr ID-TIMS isotopic–geochronological results of a comparative study of 12 samples of volcanic rocks of the Bashkirian Meganticlinorium, which were previously dated by zircons from these samples using the U‒Pb SHRIMP-II method showing the predominance of the Paleozoic ages among three stratigraphic levels with Riphean magmatic events in the South Urals, are presented. New ¹⁴⁷Sm‒¹⁴³Nd and Rb‒Sr ID-TIMS isotopic data showed that the volcanic rocks evolved as a result of crustal–mantle interaction. The Nd model ages (T_DM) (2302–2540 Ma) of volcanic rocks of the Taratash Anticlinorium represent the ages of the protolith characterized by ε_Nd(t) values from –17.4 to –20.5. The T_DM value (2033 Ma) of the Paleozoic volcanic rocks of the Yamantau Anticlinorium indicates a younger (Paleoproterozoic) substrate. The minimum Nd model ages (T_DM = 1160–1233 Ma) are determined for the volcanic rocks, which are spatially related to metabasalts of the Igonin magmatic event (707‒732 Ma) in the Tirlyan Syncline. The smallest ε_Nd(t) values (–3.2, –0.9, –0.7) indicating a decrease in the amount of a crustal component relative to the mantle material are determined for the Paleozoic metabasalts in the Tirlyan Syncline in the eastern wing of the Bashkirian Meganticlinorium, which is probably related to the activation of plume processes in the eastern part of the orogen. The Rb‒Sr and ¹⁴⁷Sm‒¹⁴³Nd ID-TIMS isotopic systematics of the studied volcanic rocks expands our understanding of mantle–crustal interactions within three stratigraphic levels with Riphean magmatic events of the South Urals.

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南乌拉尔 Bashkirian Meganticlinorium Riphean Sequences 的玄武岩：新的 147Sm-143Nd 和 Rb-Sr ID-TIMS 同位素约束

摘要介绍了对巴什基尔巨型火山岩的 12 个样本进行比较研究的 147Sm-143Nd 和 Rb-Sr ID-TIMS 同位素-测序结果，这些样本的锆石以前曾用 U-Pb SHRIMP-II 方法测定过年代，结果表明在南乌拉尔地区发生里氏岩浆事件的三个地层中，古生代的年代占主导地位。新的 147Sm-143Nd 和 Rb-Sr ID-TIMS 同位素数据显示，火山岩的演化是地壳与地幔相互作用的结果。塔拉塔什反褶火山岩的钕模型年龄（TDM）（2302-2540 Ma）代表了原岩的年龄，其特征是εNd(t)值从-17.4到-20.5。山头坳陷古生代火山岩的TDM值（2033Ma）表明其基质较年轻（古生代）。为火山岩确定的最小钕模型年龄（TDM = 1160-1233 Ma）在空间上与铁尔梁山脉伊戈宁岩浆事件（707-732 Ma）的新元古代岩石有关。巴什基尔特大岩浆岩东翼蒂尔扬合成岩中的古生代变质岩被测定出最小的εNd(t)值（-3.2、-0.9、-0.7），表明相对于地幔物质，地壳成分的数量有所减少，这可能与造山带东部羽流过程的激活有关。所研究火山岩的铷-锶和 147Sm-143Nd ID-TIMS 同位素系统学扩大了我们对地幔-地壳相互作用在南乌拉尔地区里更新世岩浆事件的三个地层层次的了解。

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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.