ABSTRACT

We report new results of a comprehensive study into Carboniferous – Early Permian granite magmatism of the northern Taimyr Peninsula, Russia (southern part of the Kara Terrane). U-Pb zircon ages (SHRIMP and LA–ICP–MS) represent the crystallization ages of these intrusions and range from ca. 344.5 to 288.4 Ma, defining the onset of granite magmatism during the Early Carboniferous (Visean; ca. 344 Ma) and its termination in the Early Permian (Artinskian; ca. 288 Ma). Ar-Ar dating of micas and amphiboles indicates that Late Palaeozoic tectonic activity in northern Taimyr ceased during the Middle Permian (Roadian; ca. 272 Ma). Rb/Sr and Sm/Nd isotopic data from the same intrusions, show initial (⁸⁷Sr/⁸⁶Sr)i ratios of between 0.70288 and 0.71027, with εNd(t) values range between −3.3 and +3.1. The combined geochemical and isotopic compositions of the granites describe an affinity to peraluminous I-type granites, probably formed in an Andean-type active continental margin setting. Our new geochemical, isotopic, and geochronological data indicate the existence of a long-lived (ca. 56 Myr) Andean-type active continental margin along the southern edge of the Kara Terrane during the Late Palaeozoic. Furthermore, our study reveals a causal relationship between Late Palaeozoic magmatism across northern Taimyr and closure of the Uralian Ocean.

摘要

我们报告了对俄罗斯泰米尔半岛北部（喀拉地层南部）石炭纪 - 早二叠世花岗岩岩浆作用的综合研究的新结果。U-Pb 锆石年龄（SHRIMP 和 LA-ICP-MS）代表这些侵入体的结晶年龄，范围从约 344.5 至 288.4 Ma，定义了早石炭纪（维森纪；约 344 Ma）花岗岩岩浆活动的开始及其在早二叠纪（Artinskian；约 288 Ma）的终止。云母和角闪石的 Ar-Ar 年代测定表明，泰米尔北部的晚古生代构造活动在中二叠纪（Roadian；约 272 Ma）期间停止。来自同一侵入体的 Rb/Sr 和 Sm/Nd 同位素数据显示初始 ( ⁸⁷ Sr/ ⁸⁶Sr)i 比率介于 0.70288 和 0.71027 之间，εNd(t) 值范围介于 -3.3 和 +3.1 之间。花岗岩的地球化学和同位素组合描述了与过铝 I 型花岗岩的亲和力，可能形成于安第斯型活动大陆边缘环境。我们新的地球化学、同位素和地质年代学数据表明，晚古生代沿喀拉地体南缘存在一个长寿命（约 56 Myr）安第斯型活动大陆边缘。此外，我们的研究揭示了泰米尔北部晚古生代岩浆活动与乌拉尔洋闭合之间的因果关系。