The Tuva–Mongolian terrane (TMT) of the Central Asian Orogenic Belt is a composite structure with a Vendian–Cambrian terrigenous–carbonate cover. The formation of the northern part of TMT is marked by the granitoids of the Sumsunur Complex with an age of 785 ± 11 Ma. The Sangilen and Khan-Khukhay blocks of its southern part also form a composite structure, which originated during Early Paleozoic (500–490 Ma) low–moderate pressure regional metamorphism reaching amphibolites–granulite facies. The earlier high-pressure metamorphism was established in the Moren Complex of both the blocks. In the Sangilen block, this metamorphism reached conditions of kyanite–garnet–biotite–orthoclase subfacies of amphibolites facies (temperature ~750°C, pressure 9–10 kbar). The upper age limit of this metamorphism is determined by granites with an age of 536 ± 6 Ma, which cut across migmatized biotite gneisses of the Moren Complex. The latter are intruded by the granitoids of the Ortoadir pluton, which were previously dated at 521 ± 12 Ma (U-Pb method, TIMS). Its emplacement predated the Early Paleozoic low–moderate pressure metamorphism, the timing of which is constrained by syn- and postmetamorphic granitoids with ages of 496 ± 4 and 489 ± 3 Ma. The age of 513 ± 4 Ma established for the granitoids of the Ortoadir Complex in the Khan-Khukhay Block more accurately constrains the lower age boundary of collision processes. This determined the amalgamation of the fragments of the high-pressure metamorphic belt with basement and carbonate–shelf cover units of the Tuva–Mongolian terrane, as well as the upper age boundary of early metamorphism. The timing of the main mappable structure of the Khan-Khukhay Block and low–moderate pressure regional metamorphism is marked by the synmetamorphic granitoids with an age of 505 ± 2 Ma. In general, the metamorphic rocks of the Sangilen, Khan-Khukhay, and Kaakhem blocks can be considered as fragments of the Late Ediacaran high-pressure metamorphic belt, which were amalgamated to the western margin of TMT within 515–505 Ma, after emplacement of the granitoids of the Ortoadir Complex, and were reworked by regional Early Paleozoic low–moderate pressure metamorphism.

中文翻译：

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中亚造山带图瓦-蒙古地带内新元古代-早古生代变质带晚期的构造位置

中亚造山带的图瓦－蒙古地层（TMT）是一个复合结构，具有一个文迪亚－寒武纪的陆源－碳酸盐覆盖层。TMT北部的形成以Sumsunur Complex的花岗岩类为特征，年龄为785±11 Ma。其南部的Sangilen和Khan-Khukhay块也形成了一个复合结构，其起源于早古生代（500-490 Ma）低-中等压力区域变质作用，达到了闪石-粒状相。早先的高压变质作用建立在两个区块的莫伦复合体中。在桑吉兰区块，这种变质作用达到了角闪石相的蓝晶石-石榴石-黑云母-正长石亚相的条件（温度〜750°C，压力9-10 kbar）。这种变质的年龄上限由年龄为536±6 Ma的花岗岩确定，横越了Moren Complex的经过迁移的黑云母片麻岩。后者被Ortoadir岩体的花岗石侵入，该岩体以前的年代为521±12 Ma（U-Pb法，TIMS）。它的位置早于早古生代低-中等压力变质作用，其时机受同质和后变质花岗岩的年龄限制，年龄分别为496±4和489±3 Ma。在Khan-Khukhay区块中的Ortoadir复合体的花岗岩中确定的513±4 Ma年龄更准确地限制了碰撞过程的较低年龄边界。这决定了高压变质带的碎片与图瓦-蒙古地层的基底和碳酸盐-地壳盖单元的合并，以及早期变质的年龄边界。Khan-Khukhay块的主要可映射结构的时间和中低压力区域变质的特征是年龄为505±2 Ma的同形花岗岩。通常，可以将桑吉伦，汗-胡克和卡哈姆地块的变质岩视为埃迪亚卡拉晚期高压变质带的碎片，这些碎屑岩在西格伦冲刺之后在515-505 Ma内合并到TMT的西缘由Ortoadir复合体的花岗岩组成，并通过区域早古生代低-中等压力变质作用进行了改造。