From Rodinia to Gondwanaland: A tale of detrital zircon provenance analyses from the southern Nanhua Basin, South China
From Rodinia to Gondwanaland: A tale of detrital zircon provenance analyses from the southern Nanhua Basin, South China
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DOI：
10.2475/01.2014.08
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发表时间：
2014-01
影响因子：
2.9
通讯作者：
W. Yao;Zheng‐Xiang Li;Wuzhi Li;Xian‐Hua Li;Jin-Hui Yang
中科院分区：
文献类型：
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作者：
W. Yao;Zheng‐Xiang Li;Wuzhi Li;Xian‐Hua Li;Jin-Hui Yang
新元古代和早古生代华南地块的古地理位置对于理解Rodinia超大陆裂解到冈瓦纳大陆形成的过渡具有重要意义。对华南板块西南部寒武系沉积岩中碎屑锆石的原位U-Pb年龄和Hf-O同位素综合分析表明，主要年龄群为2500 Ma、1100 ~ 900 Ma、850 ~ 750 Ma和650 ~ 500 Ma，其中以1100 ~ 980 Ma为主，占总年龄的约50%。锆石Hf-O同位素结果表明，源区前寒武纪经历了3个时期的地壳生长（3.0Ga、2.5Ga和1.0Ga），主要的地壳改造发生在580 ~ 500 Ma。由U-Pb和Hf分析所定义的源源区明显不同于已知的SCB的构造岩浆记录，或西澳大利亚或西劳伦，但匹配以及埃迪卡拉纪（最新新元古代）-寒武纪碎屑沉积岩和花岗质侵入体在西北印度喜马拉雅山。SCB-NW印度种源联系似乎始于埃迪卡拉纪。我们认为，在埃迪卡拉-奥陶纪期间，SCB从Rodinia中部分离出来后与印度西北部碰撞，导致印度北方边缘的“泛非洲”Kurgiakh/Bhimphedian造山带以及华南的板内武夷-云开造山带（>460 Ma-415 Ma）。因此，南华盆地埃迪卡拉-下古生界碎屑沉积岩系为华南板块与冈瓦纳大陆碰撞过程中形成的前陆沉积。
The paleogeographic positions of the South China Block (SCB) during the Neoproterozoic and early Paleozoic are important for understanding the transition from the break-up of the supercontinent Rodinia to the formation of Gondwanaland. Integrated in situ U-Pb ages and Hf-O isotope analyses of detrital zircons from Cambrian sedimentary rocks in the southwestern SCB reveal major age populations at 2500 Ma, 1100 to 900 Ma, 850 to 750 Ma and 650 to 500 Ma, with a predominant group at ∼980 Ma that counts for ∼50 percent of all analyses. Zircon Hf-O isotopic results suggest three Precambrian episodes of juvenile crustal growth for the source area(s) (3.0 Ga, 2.5 Ga and 1.0 Ga), with major crustal reworking at 580 to 500 Ma. The source provenance as defined by the U-Pb and Hf analyses is distinctly different from the known tectonomagmatic record of the SCB, or that of western Australia or western Laurentia, but matches well with that of the Ediacaran (latest Neoproterozoic)–Cambrian clastic sedimentary rocks and granitic intrusions in the NW Indian Himalaya. The SCB–NW India provenance linkage appears to have started from the Ediacaran. We propose that after breaking away from central Rodinia, the SCB collided with NW India during the Ediacaran–Ordovician time, causing the “Pan-African” Kurgiakh/Bhimphedian orogeny at the northern margin of India as well as the intraplate Wuyi-Yunkai orogeny (>460 Ma − 415 Ma) in South China. The Ediacaran–lower Paleozoic clastic sedimentary rocks in the Nanhua Basin are therefore interpreted to be foreland deposits formed during the collision of the SCB with Gondwanaland.