...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Gondwana research: international geoscience journal >Low-delta O-18 mantle-derived magma in Panjal Traps overprinted by hydrothermal alteration and Himalayan UHP metamorphism: Revealed by SIMS zircon analysis
【24h】

Low-delta O-18 mantle-derived magma in Panjal Traps overprinted by hydrothermal alteration and Himalayan UHP metamorphism: Revealed by SIMS zircon analysis

机译：Panjal陷阱中的低ΔO-18披风型岩浆被水热改变和喜马拉雅UHP变质形式叠印：SIMS锆石分析透露

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

We report two generations of low-delta O-18 zircons from the Himalayan eclogites and their host gneisses. In situ SIMS delta O-18 analyses on single zircon crystals (with known age and Hf isotope ratios) from two populations of chemically distinct zircons demonstrate a complex history: (1) an early low-delta O-18 mantle-derived magma, (2) followed by post-emplacement high-temperature meteoric-water alteration and finally (3) crystallization of new, low-delta O-18 minerals during the ultrahigh-pressure metamorphism. Magmatic zircon,(269 Ma) in Group I eclogites yielded delta O-18 values from 1.9 to 4.6 parts per thousand VSMOW with an average value of 4.0 +/- 0.2 (n = 35, the error is 2SD analytical precision and "n" represents number of analyzed spots), which is lower than the typical mantle values (5.3 +/- 0.6, 2SD). In contrast, metamorphic zircons (45 Ma) in Group II eclogites preserve unusually low, negative delta O-18 values from -3.9 to -2.7 parts per thousand (average: -3.4 +/- 0.4, n = 35, 2SD). Zircons in felsic gneiss that surround Group II eclogites have inherited magmatic cores (ca. 260 Ma) with delta O-18 values of ca. 2.9 parts per thousand, which decrease to -0.1 parts per thousand in metamorphic (ca. 45 Ma) rims. These zircons preserve lower delta O-18 values than would be equilibrated with typical mantle. The low-delta O-18 values in magmatic zircons suggest that the mafic protolith to these eclogites formed from a hydrothermally altered subducted oceanic crust and the negative delta O-18 values in metamorphic zircons indicate hydrothermal alteration after crystallization of the mafic magmas but before growth of metamorphic zircons. This study reports evidence for melting of subducted low-delta O-18 ocean crust to form low-delta O-18 mantle-derived mafic magmas as previously proposed by Cartwright and Valley (1991, Geology 19, 578-581) for Proterozoic Scourie Dikes. (C) 2017 International Association for Gondwana Research. Published by Elsevier B.V.
机译：我们从喜马拉雅狂热和宿主口中报告两代低δO-18锆石。在原位模拟人生中，从两个化学不同的锆石种群中分析单个锆石晶体（具有已知的年龄和HF同位素比），证明了复杂的历史：（1）早期的低δO-18搭式岩浆岩浆（ 2）随后进行后施加高温迁移水改变，最后（3）结晶新的低δ18矿物质在超高压变质期间。 Magmatic Zircon（269 mA）在I组中，eClogites从1.9到4.6分别产生的平均值为4.0 +/- 0.2（n = 35，错误是2SD分析精度和“N”，从1.9到4.6分别产生ΔO-18值。表示分析的斑点的数量），其低于典型的地幔值（5.3 +/- 0.6,2SD）。相反，II组eClogites的变质氧化锆（45mA）在-3.9至-2.7份的异常低，负ΔO-18值均为千分之一（平均：-3.4 +/- 0.4，n = 35，2SD）。 Felsic Gneiss中的Zircons环绕第II reclogites遗传了岩浆核心（CA. 260 mA），具有CA的Delta O-18值。 2.9份百分之一，其变质（CA.45mA）轮辋下降至0.10.1份。这些氧化杖保持比典型地幔平衡的更低的ΔO-18值。 Magmatic Zircons中的低δO-18值表明，由热水改变的底层海藻和变质氧化锆中的阴性ΔO-18值形成的母乳型促果实和变质氧化锆中的负δO-18值表示水热改变，但在生长之前结晶但在生长之前变质锆石。本研究报告了介质的低δO-18海洋地壳融化的证据，以形成以前由印刷和谷（1991，地质19,578-581）为先前推荐的低ΔO-18地幔衍生的MAFIC魔法魔法岩。 （c）2017年加州研究国际协会。 elsevier b.v出版。

著录项

相似文献

  • 外文文献
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号