| 松潘-甘孜地区三叠系碎屑沉积岩地球化学特征及其锆石年龄研究 |
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| 引用本文：刘飞,陈岳龙,苏本勋,兰中伍,蒋丽婷.2006.松潘-甘孜地区三叠系碎屑沉积岩地球化学特征及其锆石年龄研究[J].地球学报,27(4):289-296. |
| DOI：10.3975/cagsb.2006.04.01 |
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| 基金项目:国家自然科学基金重点项目(编号:40234052)，面上项目(编号:40173007)，教育部重点科研项目(编号:03032) |
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| 中文摘要:松潘—甘孜地块地处中国西南部,是中国大陆构造中重要的基本构造单元,三叠系碎屑沉积岩广泛分布,本文对松潘—甘孜地块的三叠系碎屑沉积岩4个样品的稀土元素及锆石U_Pb地球化学特征进行了系统研究。4个样品的稀土元素分布型式特征非常接近,这表明松潘—甘孜地区的三叠系碎屑沉积岩具有相同的来源。明显的轻、重元素分馏和铕异常则表明碎屑岩源区地壳内有较的深熔作用。锆石Th/U比和阴极发光表明它们基本上来自岩浆岩物源区。SHRI MP结果显示206Pb/238U年龄集中在200~1000Ma和1600~2400Ma,其中1600~2400Ma的锆石年龄记录了扬子克拉通基底的形成事件;200~1000Ma的锆石年龄反映了青白口纪及东吴运动期间扬子克拉通强烈的岩浆活动。此外,中三叠世末期秦岭造山带全面隆升成山,也阻断了华北克拉通为该区提供碎屑沉积岩的可能,因此,松潘—甘孜地区的三叠系碎屑沉积岩来源于杨子克拉通。 |
| 中文关键词:碎屑沉积岩 松潘—甘孜地块 锆石U-Pb定年 物质来源 |
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| Geochemistry and Zircon Ages of Triassic Detrital Sedimentary Rocks from the Ganze-Songpan Block |
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| Abstract:The Songpan-Ganze block in southwestern China is an important part in China's continental tectonics. Systematic REE and U-Pb isotopic studies of detrital sedimentary rocks from the Songpan-Ganze block were conducted by the authors. The results show that the chondrite-normalized REE patterns of four samples are basically consistent with each other, suggesting that these four samples have the same provenance. The Th/U values and cathodoluminescence of zircons indicate that most zircons were derived from the magmatite provenance. SHRIMP results show that the 206 Pb/ 238 U ratios cluster around the concordia of 1600～2400Ma and 200～1000Ma, which represent the formation of Yangtze craton basement and the magmatic activity of Qingbaikouan period and Dongwu movement respectively. Moreover, the Qinling orogenic belt uplifted in late Middle Triassic, which prevented the transport of detrital sedimentary from the North China craton. Therefore, the provenance of the Triassic sedimentary rocks in the Songpan-Ganze block seemed to be the Yangtze craton instead of the North China craton. |
| keywords:detrital sedimentary rocks Songpan-Ganze block zircon U-Pb dating material source |
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