Identification of 3.5 Ga detrital zircons from Yangtze craton in South China and the implication for Archean crust evolution
Identification of 3.5 Ga detrital zircons from Yangtze craton in South China and the implication for Archean crust evolution
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DOI：
10.1080/10020070612330050
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发表时间：
2006-10
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影响因子：
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通讯作者：
L. Xiaoming;G. Shan;Ling Wenli;Yu Honglin;Hu Zhao-chu
中科院分区：
文献类型：
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作者：
L. Xiaoming;G. Shan;Ling Wenli;Yu Honglin;Hu Zhao-chu
摘要 对宜昌三峡地区连沱组震旦系砂岩和南沱组红粉云岩中数百颗碎屑锆石进行LA-ICP-MS U-Pb定年，鉴定出3 319~3 508 Ma锆石。它们的 207Pb/206Pb 和 206Pb/238U 年龄显示出极好的一致性（一致度 99%–100%）。其CL图像显示出发育良好的振荡分带，Th/U比值在0.46-0.76之间，这表明它们是太古代中早期形成的火成锆石。这些锆石是迄今为止在扬子克拉通发现的最古老的锆石。但进一步考察，在崆岭群变质岩中并未发现年龄大于3.3 Ga的碎屑锆石，这表明扬子克拉通存在比高级变质崆岭地体更古老的地壳。国家自然科学基金（批准号：40472099和40521001）和高校长江学者和创新团队计划（批准号：IRT0441）资助
Abstract The LA-ICP-MS U-Pb dating of hundreds of detrital zircon grains from the Sinian sandstones of Liantuo formation and tillites of Nantuo formation at Sanxia area in Yichang identified 3319–3508 Ma zircon grains. Their 207Pb/206Pb and 206Pb/238U ages show excellent agreement (concordia degree 99%–100%). Their CL images exhibit well-developed oscillatory zoning and the Th/U ratios are within 0.46–0.76, implying that they are igneous zircons which formed during middle-early Archean. These zircons are the oldest ones discovered in Yangtze craton until now. However, the detrital zircons with ages older than 3.3 Ga in the metamorphic rocks of Kongling group were not found by further investigation, which suggests the presence of crust older than high-grade metamorphic Kongling terrain in Yangtze craton. Supported by National Natural Science Foundation of China (Grant Nos. 40472099 and 40521001) and Program for Changjiang Scholars and Innovative Research Team in University (Grant No. IRT0441)