Differential exhumation and cooling history of North Qaidam UHP metamorphic rocks, NW China: Constraints from zircon and rutile thermometry and U-Pb geochronology
Differential exhumation and cooling history of North Qaidam UHP metamorphic rocks, NW China: Constraints from zircon and rutile thermometry and U-Pb geochronology
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中国西北柴达木北超高压变质岩的差异折返和冷却历史：来自锆石和金红石测温和U-Pb年代学的约束
DOI：
10.1016/j.lithos.2014.06.018
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发表时间：
2014-09
期刊：
影响因子：
3.5
通讯作者：
Li, Qiuli
中科院分区：
文献类型：
--
作者：
Zhang, Lifei;Christy, Andrew G.;Song, Shuguang;Li, Qiuli
利用LA-ICP-MS和西姆斯对柴北缘超高压变质带榴辉岩进行了锆石和金红石U-Pb年龄和微量元素分析。锆的金红石和钛的锆石温度计给出一致的峰值变质温度为两个新鲜的榴辉岩样品。由卡榴辉岩的锆石和金红石U-Pb年龄分别为430.2 ± 3.7Ma和407 ± 16 Ma。都兰北部榴辉岩的锆石记录了两次明显的榴辉岩相变质事件，分别为446.6 ± 4.1和430.5 ± 4.7Ma，锆石中TTi值分别为684 ± 16 °C和649 ± 26 °C，而同一榴辉岩样品的金红石U-Pb年龄为416 ± 10 Ma。这些金红石U-Pb年龄被解释为记录了这些岩石冷却到金红石中Pb的封闭温度的时间（在这里，被认为是成为一个新的温度）。570 °C）。因此，我们得到了约3-4 °C/Ma的Yuka和北都兰火山的缓慢冷却速率。都兰南部一个麻粒岩相叠加榴辉岩样品的金红石U-Pb年龄为383 ± 10 Ma。结合文献中的年代学和温度数据，研究表明，在麻粒岩相事件之后，南都兰的剥露时间比其他样品晚，冷却速率快，约为6.6 °C/Ma。T-tpaths结果表明，柴北缘榴辉岩的冷却历史比以往认为的要慢得多，同时还表明，虽然鱼卡榴辉岩和北都兰榴辉岩的热历史相似，但南都兰榴辉岩却截然不同。因此，柴北缘发生了超高压变质岩的差异折返和侵位。
We analyze zircon and rutile U–Pb ages and trace elements using LA-ICP-MS and SIMS of eclogites from the North Qaidam ultra-high-pressure metamorphic belt in NW China. Zr-in-rutile and Ti-in-zircon thermometries give consistent peak metamorphic temperatures for two fresh eclogite samples. Zircon and rutile U–Pb dating from the Yuka eclogite yielded ages of 430.2 ± 3.7 Ma and 407 ± 16 Ma respectively. Zircons from North Dulan eclogite record two distinct eclogite-facies metamorphic events at 446.6 ± 4.1 and 430.5 ± 4.7 Ma, withTTi-in-zircon= 684 ± 16 °C and 649 ± 26 °C respectively, while rutile U–Pb dating for the same North Dulan eclogite sample yielded an age of 416 ± 10 Ma. These rutile U–Pb ages are interpreted to record the time when these rocks cooled down to the closure temperature of Pb in rutile (here, taken to beca. 570 °C). Thus, we obtain a slow cooling rate of ~ 3–4 °C/Ma for Yuka and North Dulan terranes. For one granulite-facies overprinted South Dulan eclogite sample, rutile U–Pb dating gave a younger age of 383 ± 10 Ma. Combined with literature chronological and temperature data for South Dulan, the data imply later exhumation than the other samples with a faster cooling rate of ~ 6.6 °C/Ma, after the granulite-facies event. TheT–tpaths obtained show that the North Qaidam eclogites experienced considerably slower cooling history than previously assumed, and also that while the thermal histories of the Yuka and North Dulan eclogites resemble one another, the South Dulan eclogite is quite distinct. So, a differential exhumation and emplacement of UHP metamorphic rocks occurred in the North Qaidam.
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影响因子：
4.5
作者：
D. Rubatto;J. Hermann
通讯作者：
D. Rubatto;J. Hermann
影响因子：
3.9
作者：
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Shuguang Song;Lifei Zhang;Y. Niu;L. Su;B. Song;Dunyi Liu
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3.9
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作者：
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