Pb and Nd isotopic composition of granitoids from the Lake Zone, Mongolian and Gobi Altai was analyzed to decipher the continental crustal growth of heterogeneous terranes of the Central Asian orogenic belt. The granitoids were generated in the Late Neoproterozoic–Early Paleozoic juvenile crust of the Lake Zone during island-arc, accretion, and post-accretionary stages at 535–440 Ma. Their Pb and Nd isotopic characteristics are similar and illustrate the dominance of juvenile material in the source of granitoids of all three stages. An insignificant terrigenous contribution in their source provides dispersion of the Pb isotopic composition at a weak effect on the Nd isotopic composition. The Pb and Nd isotopic study of Middle Paleozoic (∼380–355 Ma) synkinematic and Late Paleozoic (∼350–270 Ma) post-kinematic granitoids in the Mongolian and Gobi Altai revealed a significant heterogeneity of their source, which is mainly inherited from terrigenous rocks of the Altai accretionary wedge variably metamorphosed under greenschist to granulite facies conditions. The main source of Altai terrigenous sediments was volcanic rocks from the Lake Zone juvenile crust with subordinate contribution of more mature rocks from the Tuva-Mongolian and Dzabkhan microcontinents, which supplied sediments with highly radiogenic Pb and Nd isotopic composition. The Pb isotopic compositions of the granitoids from the Lake Zone, Mongolian and Gobi Altai, and also the Trans-Altai Gobi (Savatenkov et al., 2016) show that their mantle source has an elevated Th/U ratio compared to the depleted mantle (Kramers and Tolstikhin, 1997). This is a hallmark of the depleted mantle source of the Paleo-Asian province. Juvenile continental crust terrains of the Central Asian orogenic belt (Lake Zone and Trans-Altai Gobi terranes) were formed in various tectonics settings. The island-arc complexes of the Lake Zone developed near the Precambrian Tuva-Mongolian and Dzabkhan microcontinents, which supplied terrigenous material with highly radiogenic Pb to granitoid sources. The Trans-Altai Gobi was a system of ensimatic island arcs separated from the Siberian paleocontinent by a continent-dipping subduction zone, which prevented the influx of ancient terrigenous material from the continent.

中文翻译：

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湖区，蒙古和戈壁阿尔泰地区花岗岩类的铅和钕同位素数据，对中亚造山带地壳生长有影响

分析了湖区，蒙古族和戈壁阿尔泰地区花岗岩类的铅和钕同位素组成，以解释中亚造山带非均质地层的大陆壳生长。花岗岩是在岛弧，增生和增生后的535-440 Ma期间，在湖区的新元古代晚期至古生代幼年地壳中生成的。它们的Pb和Nd同位素特征相似，说明了这三个阶段的花岗石来源中少年物质的优势。来源中微不足道的陆源贡献使Pb同位素组成的分散对Nd同位素组成的影响很小。蒙古和戈壁阿尔泰的中古生代（〜380–355 Ma）和后古生代（〜350–270 Ma）的运动后花岗岩类的Pb和Nd同位素研究表明，它们的来源存在显着的异质性，主要是从阿尔泰增生楔的陆相岩石在绿泥岩至粒相条件下变质。阿尔泰陆源沉积物的主要来源是湖区幼年壳的火山岩，而图瓦-蒙古和扎布汗微洲的更成熟岩石的次要贡献是，这些沉积物为沉积物提供了高放射性的铅和钕同位素组成。湖区，蒙古族和戈壁阿尔泰以及反阿尔塔戈壁的花岗岩中铅的铅同位素组成（Savatenkov等，2016年）表明，与枯竭的地幔相比，其地幔源的Th / U比升高（Kramers和Tolstikhin，1997）。这是古亚洲省地幔资源枯竭的标志。中亚造山带的青少年大陆壳地形（湖区和跨阿尔泰戈壁地带）在各种构造背景下形成。湖区的岛弧复合体在前寒武纪的Tuva-Mongolian和Dzabkhan微洲附近发展，向花岗岩类源提供陆源物质和高放射性的Pb。Trans-Altai戈壁是一个由大陆浸没俯冲带与西伯利亚古大陆隔开的环岛弧形系统，阻止了古代陆源物质从该大陆流入。这是古亚洲省地幔资源枯竭的标志。中亚造山带的青少年大陆壳地形（湖区和跨阿尔泰戈壁地带）在各种构造背景下形成。湖区的岛弧复合体在前寒武纪的Tuva-Mongolian和Dzabkhan微洲附近发展，向花岗岩类源提供陆源物质和高放射性的Pb。Trans-Altai戈壁是一个由大陆浸没俯冲带与西伯利亚古大陆隔开的环岛弧形系统，阻止了古代陆源物质从该大陆流入。这是古亚洲省地幔资源枯竭的标志。中亚造山带的青少年大陆壳地形（湖区和跨阿尔泰戈壁地带）在各种构造背景下形成。湖区的岛弧复合体在前寒武纪的Tuva-Mongolian和Dzabkhan微洲附近发展，向花岗岩类源提供陆源物质和高放射性的Pb。Trans-Altai戈壁是一个由大陆浸没俯冲带与西伯利亚古大陆隔开的环岛弧形系统，阻止了古代陆源物质从该大陆流入。中亚造山带的青少年大陆壳地形（湖区和跨阿尔泰戈壁地带）在各种构造背景下形成。湖区的岛弧复合体在前寒武纪的Tuva-Mongolian和Dzabkhan微洲附近发展，向花岗岩类源提供陆源物质和高放射性的Pb。Trans-Altai戈壁是一个由大陆浸没俯冲带与西伯利亚古大陆隔开的环岛弧形系统，阻止了古代陆源物质从该大陆流入。中亚造山带的青少年大陆壳地形（湖区和阿尔泰戈壁跨地带）在各种构造背景下形成。湖区的岛弧复合体在前寒武纪的Tuva-Mongolian和Dzabkhan微洲附近发展，向花岗岩类源提供陆源物质和高放射性的Pb。跨阿尔泰戈壁是一个由大陆浸没俯冲带与西伯利亚古大陆隔开的环岛弧的系统，阻止了古代陆源物质从该大陆涌入。