The Tibetan Plateau is composed of several microblocks, the tectonic affinity and paleogeographic correlations of which remain enigmatic. We investigated the Amdo and Jiayuqiao microblocks in central Tibet Plateau with a view to understand their tectonic setting and paleogeographic position within the Neoproterozoic supercontinent Rodinia. We present zircon U-Pb and Lu-Hf isotope, and whole-rock geochemical data on Neoproterozoic granitic gneisses from these microblocks. Zircon grains from the Jiayuqiao granitic gneiss yielded an age of 857 ± 9 Ma with variable εHf(t) values (–8.9 to 4.0). The Amdo granitic gneisses yielded ages of 893 ± 5 Ma, 807 ± 5 Ma, and 767 ± 11 Ma, with εHf(t) values in the range of –4.9 to 3.5. Geochemically, the granitoids belong to high-K calc-alkaline series, with the protolith derived from partial melting of ancient crustal components. The ascending parental magma of the Amdo granitoids experienced significant mantle contamination as compared to the less contaminated magmas that generated the Jiayuqiao intrusions. In contrast to the Lhasa, Himalaya, South China, and Tarim blocks, we suggest that the Amdo and Jiayuqiao microblocks probably formed a unified block during the Neoproterozoic and were located adjacent to the southwestern part of South China craton. The Neoproterozoic magmatism was probably associated with the subduction of the peripheral ocean under the South China craton and the delamination of lithospheric mantle beneath the Jiangnan orogen.

中文翻译：

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青藏高原的新元古代安多和嘉yu桥微区块：对罗丹尼亚重建的启示

青藏高原是由几个微块组成的，其构造亲和力和古地理相关性仍然是个谜。我们研究了青藏高原中部的安多和贾玉桥微区块，以了解它们在新元古代超大陆罗丹尼亚内的构造背景和古地理位置。我们介绍了锆石U-Pb和Lu-Hf同位素，以及来自这些微区块的新元古代花岗岩片麻岩的全岩石地球化学数据。嘉yu桥花岗片麻岩中的锆石晶粒年龄为857±9 Ma，εHf（t）值可变（–8.9至4.0）。Amdo花岗岩片麻岩的年龄为893±5 Ma，807±5 Ma和767±11 Ma，εHf（t）值在–4.9至3.5范围内。从地球化学上讲，类花岗岩属于高K钙碱性系列，其原生石来自古代地壳成分的部分融化。与污染较少的产生嘉Jia桥侵入岩浆的岩浆相比，安多花岗岩类的上升母岩浆受到明显的地幔污染。与拉萨，喜马拉雅，华南和塔里木区块相反，我们建议安多和贾玉桥微区块可能在新元古代时期形成一个统一的区块，并且与华南克拉通的西南部分相邻。新元古代的岩浆作用可能与华南克拉通下的外围海洋俯冲和江南造山带下的岩石圈地幔分层有关。与污染较少的产生嘉Jia桥侵入岩浆的岩浆相比，安多花岗岩类的上升母岩浆受到明显的地幔污染。与拉萨，喜马拉雅，华南和塔里木区块相反，我们建议安多和贾玉桥微区块可能在新元古代时期形成一个统一的区块，并且与华南克拉通的西南部分相邻。新元古代的岩浆作用可能与华南克拉通下的外围海洋俯冲和江南造山带下的岩石圈地幔分层有关。与污染较少的产生嘉Jia桥侵入岩浆的岩浆相比，安多花岗岩类的上升母岩浆受到明显的地幔污染。与拉萨，喜马拉雅，华南和塔里木区块相反，我们建议安多和贾玉桥微区块可能在新元古代时期形成一个统一的区块，并且与华南克拉通的西南部分相邻。新元古代的岩浆作用可能与华南克拉通下的外围海洋俯冲和江南造山带下的岩石圈地幔分层有关。我们认为，安多和嘉yu桥微区块可能在新元古代形成了一个统一的区块，并且位于华南克拉通的西南部附近。新元古代的岩浆作用可能与华南克拉通下的外围海洋俯冲和江南造山带下的岩石圈地幔分层有关。我们认为，安多和嘉yu桥微区块可能在新元古代形成了一个统一的区块，并且位于华南克拉通的西南部附近。新元古代的岩浆作用可能与华南克拉通下的外围海洋俯冲和江南造山带下的岩石圈地幔分层有关。