Zr-in-rutile thermometry in HP/UHP eclogites from Western China
Zr-in-rutile thermometry in HP/UHP eclogites from Western China
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DOI：
10.1007/s00410-009-0486-2
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发表时间：
2010-01
影响因子：
3.5
通讯作者：
Guibin Zhang;D. Ellis;A. Christy;Lifei Zhang;Shuguang Song
中科院分区：
文献类型：
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作者：
Guibin Zhang;D. Ellis;A. Christy;Lifei Zhang;Shuguang Song
对中国西部榴辉岩进行了四次金红石中锆测温校准。在这里，我们表明，如果金红石与 Qtz 和 Zrn 平衡生长，并隔离在石榴石内部，它会保留其 Zr 成分，并且不会因与主体石榴石进行阳离子交换而发生成分变化。因此，它保留了其形成的 P-T 条件的组成和宿主石榴石的生长分区。对于 HP/UHP 变质温度，Tomkins 等人。 (J Metamorph Geol 25:703–713, 2007) 校准产生的温度与之前的研究一致，而其他三个校准 (Zack 等人，Contrib Mineral Petrol 148:471–488, 2004；Watson 等人，Contrib Mineral Petrol 151:413–433, 2006；Ferry 和 Watson，Contrib Mineral Petrol in 154:429–437, 2007），不包括压力修正，系统地给出较低的温度。石榴石中金红石包裹体的 Zr 含量从石榴石核心到边缘呈现系统性降低。石榴石边缘的金红石包裹体含有最低的 Zr 含量，与基体中的相似。分析证实，压力在改变金红石 Zr 含量的主要温度依赖性方面起着重要作用。困在石榴石中的金红石在退行过程中无法轻松重新平衡，但基质中的金红石可以做到这一点，从而提供退行 P-T 路径信息。
Four Zr-in-rutile thermometry calibrations are applied to eclogites from Western China. Here, we show that if rutile grows in equilibrium with Qtz and Zrn, and is isolated inside garnet, it preserves its Zr composition and does not undergo compositional change due to cation exchange with the host garnet. It thus preserves the composition for theP–Tconditions of its formation and the growth zoning of the host garnet. For the HP/UHP metamorphic temperature, the Tomkins et al. (J Metamorph Geol 25:703–713, 2007) calibration yields temperatures that agree well with previous studies, whereas the other three calibrations (Zack et al. in Contrib Mineral Petrol 148:471–488, 2004; Watson et al. in Contrib Mineral Petrol 151:413–433, 2006; Ferry and Watson in Contrib Mineral Petrol in 154:429–437, 2007), which do not include a pressure correction, give systematically lower temperatures. Zr contents of rutile inclusions within garnet show systematic decrease from garnet core to rim. The rutile inclusions in garnet rims contain the lowest Zr content, similar to that in the matrix. Analyses confirm that the pressure plays a significant role in modifying the primary temperature dependence of the Zr content of rutile. Rutiles trapped in garnets are unable to re-equilibrate easily during retrogression, but those in the matrix can do so, providing retrogradeP–Tpath information.