The Precambriantectonic evolution of the western Jiangnan Orogen and western Cathaysia Block:Evidence from detrital zircon age spectra and geochemistry of clastic rocks
The Precambriantectonic evolution of the western Jiangnan Orogen and western Cathaysia Block:Evidence from detrital zircon age spectra and geochemistry of clastic rocks
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江南造山带西部和华夏地块西部的前寒武纪构造演化——来自碎屑锆石年龄谱和碎屑岩地球化学的证据
DOI：
10.1016/j.precamres.2015.07.002
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发表时间：
2015
影响因子：
3.8
通讯作者：
Li C
中科院分区：
文献类型：
--
作者：
Yan Chaolei;Shu Liangsu;Santosh M.;Yao JL;Li JY;Li C
江南造山带和华夏地块构成了华南克拉通地质格架的有机组成部分。然而，这两个地区的构造属性仍存在争议。在这项研究中，我们提供了来自一组碎屑岩的 LA-ICP-MS 锆石 U-Pb 年龄、Lu-Hf 同位素以及主量和微量元素数据。江南造山带西部新元古代变质砂岩获得的247个锆石U-Pb年龄定义了三个主要年龄群体：2564-2395 Ma、2068-1849 Ma和963-730 Ma，对应于早期古元古代地壳生长、哥伦比亚超大陆的合并以及与罗迪尼亚有关的构造。华夏西部寒武系和奥陶系砂岩的 243 个锆石 U-Pb 年龄数据得出了 5 个年龄群体：2626-2392 Ma、2050-1518 Ma、1173-904 Ma、857-708 Ma 和 630-502 Ma，这可以与新太古代早期联系起来。古元古代大陆生长、与哥伦比亚超大陆相关的构造热事件、罗迪尼亚的聚集和分裂以及泛非事件。 630-502Ma人口与新元古代晚期到古生代早期冈瓦纳超大陆的聚集有关，尽管该地区尚未报告这一事件的直接地质证据。这些结果表明，江南带西部和华夏地块西部具有不同的地壳演化历史，但密切相关。稀土地球化学和Lu-Hf同位素数据也表明，江南西部和华夏西部新元古代和早古生代碎屑的物源主要是由地壳物质改造而成。具有核-缘结构的锆石颗粒的变质边缘的年龄为912-891 Ma和853-835 Ma，表明源区新元古代发生了两个阶段的变质事件。这两次事件可能与分别与西段和东段扬子地块和华夏地块碰撞有关的构造有关。
The Jiangnan Orogen and Cathaysia Block constitute integral components in the geological framework of the South China Craton. However, the tectonic attributes of these two regions remain controversial. In this study we present LA–ICP–MS zircon U–Pb ages, Lu–Hf isotopes, and major and trace elements data from a suite of clastic rocks. Two hundred and forty seven zircon U–Pb ages obtained from the Neoproterozoic meta-sandstones in western Jiangnan Orogen define three major age populations: 2564–2395 Ma, 2068–1849 Ma and 963–730 Ma, corresponding to the early Paleoproterozoic crustal growth, amalgamation of the supercontinent Columbia and tectonics associated with Rodinia. Two hundred and forty three zircon U–Pb age data from Cambrian and Ordovician sandstones in the western Cathaysia yield five age populations: 2626–2392 Ma, 2050–1518 Ma, 1173–904 Ma, 857–708 Ma and 630–502 Ma, which can be correlated to the Neoarchean–early Paleoproterozoic continental growth, the tectono-thermal events associated with the Columbia supercontinent, the assembly and breakup of Rodinia, as well as the Pan-African event. The 630–502 Ma population correlates with the assembly of Gondwana supercontinent during late Neoproterozoic to early Paleozoic, although direct geological evidence for this event has not yet been reported from this region. These results suggest that the western Jiangnan belt and western Cathaysia Block have distinct crustal evolution histories albeit with close affinities. The REE geochemisty and Lu–Hf isotope data also indicate that the provenances of the Neoproterozoic and early Paleozoic detritus in western Jiangnan belt and western Cathaysia are mostly composed of reworked crustal materials. The metamorphic rims of zircon grains with core–rim structures yield ages of 912–891 Ma and 853–835 Ma, suggesting two phases of metamorphic events during Neoproterozoic in the source areas. These two events are likely associated with the tectonics related to the collision of Yangtze and Cathaysia blocks in the western and eastern segments, respectively.