Early Neoproterozoic assembly of the Yangtze Block decoded from metasedimentary rocks of the Miaowan Complex
Early Neoproterozoic assembly of the Yangtze Block decoded from metasedimentary rocks of the Miaowan Complex
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庙湾杂岩变沉积岩解码扬子地块早新元古代组合
DOI：
10.1016/j.precamres.2020.105787
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发表时间：
2020-05
影响因子：
3.8
通讯作者：
Li-Guang Wu
中科院分区：
文献类型：
--
作者：
Kai Lu;Xian-Hua Li;Jiu-Long Zhou;Song-Bai Peng;Hao Deng;Shun Guo;Chuan Yang;Li-Guang Wu
目前扬子地块被认为是中元古代-新元古代过渡时期形成的统一地块，但具体时间和过程缺乏约束。在这里，我们报告了扬子地块庙湾杂岩小溪口变质沉积岩中碎屑锆石的原位综合 U-Pb 和 Hf-O 同位素分析，以及侵入这些变质沉积岩的未变形和未变质白质脉中的岩浆独居石的 U-Th-Pb 和 Nd-O 同位素分析。变沉积岩碎屑锆石的 U-Pb 测年结果显示两个主要年龄峰分别为 CA970 和 900Ma。 970Ma 锆石的主要特征是类幔δ18Ozir 值（4.5–5.8‰）和高度贫化的εHf(t) 值（+5 至+14）。 900Ma 锆石大多具有与 970Ma 锆石类似的 O 和 Hf 同位素特征，但具有高 δ18O 值（6.0–9.2‰）和可变 εHf(t) 值（–33 至+7）的颗粒比例相对较小。矿脉中的独居石的年代为 ca850Ma，具有均匀的 δ18O 值（5.4–6.6‰），但 εNd(t) 值显着富集（–14.5 至 –12.6）。根据新的同位素结果和未成熟岩性，小溪口变沉积岩被解释为900~850Ma弧前盆地沉积，来自约970~900Ma弧岩的碎屑物质与庙湾洋板块向北俯冲（现今坐标）有关。 850Ma白质脉的地质和同位素特征与当地860-840Ma构造后花岗岩岩体一致，可能代表当地同时代花岗岩岩浆的分异产物。我们认为庙湾洋盆的闭合和现今统一扬子地块的形成发生在900~860Ma之间，即晚于弧前变沉积岩的沉积，早于构造后岩体的侵位。
The present Yangtze Block was proposed to be formed as a unified block in the Mesoproterozoic-Neoproterozoic transition, but the detailed timing and process are poorly constrained. Here we report integratedin situU–Pb and Hf–O isotopic analyses of detrital zircons from the Xiaoxikou metamorphosed sedimentary rocks of the Miaowan Complex in the Yangtze Block, as well as U–Th–Pb and Nd–O isotopic analyses of magmatic monazites from an undeformed and unmetamorphosed leucocratic vein intruding these metasedimentary rocks. U–Pb dating results for detrital zircons from the metasedimentary rocks display two main age peaks atca970 and 900 Ma. The 970 Ma zircons are dominantly characterized by mantle-like δ18Ozirvalues (4.5–5.8‰) and highly depleted εHf(t) values (+5 to + 14). The 900 Ma zircons mostly have O and Hf isotopic features similar to the 970 Ma zircons, except relative small proportion of grains with high δ18O values (6.0–9.2‰) and variable εHf(t) values (–33 to + 7). Monazites from the vein are dated atca850 Ma and have uniform δ18O values (5.4–6.6‰), but significantly enriched εNd(t) values (–14.5 to –12.6). Based on the new isotopic results and immature lithology, the Xiaoxikou metasedimentary rocks are interpreted to be deposited between 900 and 850 Ma in a fore-arc basin, and clastic materials derived from ca 970–900 Ma arc rocks were related to the northward subduction (present-day coordinates) of the Miaowan oceanic plate. The 850 Ma leucocratic vein shows geological and isotopic characteristics consistent with local 860–840 Ma post-tectonic granitic plutons, and may represent a fractionated product of local coeval granitic magmas. We propose that the closure of the Miaowan oceanic basin and formation of the current unified Yangtze Block occurred between 900 and 860 Ma, i.e., later than the deposition of the fore-arc metasedimentary rocks while earlier than the emplacement of the post-tectonic plutons.
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影响因子：
2.9
作者：
J. Zhao;Mei‐Fu Zhou;Jianping Zheng;W. Griffin
通讯作者：
J. Zhao;Mei‐Fu Zhou;Jianping Zheng;W. Griffin
影响因子：
--
作者：
Chuan-heng Zhang;Linzhi Gao;Zhenjie Wu;Xiaoying Shi;Q. Yan;Dajian Li
通讯作者：
Chuan-heng Zhang;Linzhi Gao;Zhenjie Wu;Xiaoying Shi;Q. Yan;Dajian Li
扬子地块西部石棉蛇绿岩：锆石SHRIMP U-Pb年龄、地球化学和Hf-O同位素特征及构造意义
影响因子：
3.8
作者：
Peiyuan Hu;Qingguo Zhai;Jun Wang;Yue Tang;Guangming Ren
通讯作者：
Guangming Ren
影响因子：
3.8
作者：
Kang Chen;Shan Gao;Y. Wu;Jing‐Liang Guo;Zhaochu Hu;Yongsheng Liu;K. Zong;Zhengwei Liang;
通讯作者：
Kang Chen;Shan Gao;Y. Wu;Jing‐Liang Guo;Zhaochu Hu;Yongsheng Liu;K. Zong;Zhengwei Liang;
影响因子：
3.8
作者：
J. Zhao;Mei‐Fu Zhou;Jianping Zheng
通讯作者：
J. Zhao;Mei‐Fu Zhou;Jianping Zheng