- 著者
- MAMI TAKEHARA KENJI HORIE TOMOKAZU HOKADA SOTARO BABA ATSUSHI KAMEI IPPEI KITANO
- 出版者
- Japan Association of Mineralogical Sciences
- 雑誌
- Journal of Mineralogical and Petrological Sciences (ISSN:13456296)
- 巻号頁・発行日
- pp.230331, (Released:2023-09-07)
The Napier Complex in East Antarctica has a complex thermal history, including ultra-high-temperature (UHT) metamorphism. Geochronology, trace element, and isotope geochemistry of zircon, apatite, and monazite in three felsic gneisses collected from Harvey Nunatak were studied using a sensitive high-resolution ion microprobe (SHRIMP) for the first time. Most zircons showed nebulous to fir-tree zoning, which is a common feature of zircons in granulite facies rocks, regardless of the core or rim. The U-Pb dating and rare earth element abundance of zircon indicated that zircon crystallization by regional metamorphism continued from 2567–2460 Ma, consistent with the previously proposed timing of UHT metamorphism. The zircon grains contained a large amount of Li (59–668 ppm). Li was incorporated with Cl at the interstitial sites of the zircon structure, and the zircons crystallized in melts with an abundant supply of Li and Cl. Monazite crystallized from apatite after the UHT metamorphism events of 2071 Ma and 1799 Ma. The U-Pb system of apatite was completely disturbed by the crystallization of monazite at 1785 Ma. In addition, the U-Pb systems of apatite and monazite were disturbed at approximately 500 Ma.
- 著者
- Kenji HORIE Tomokazu HOKADA Yoichi MOTOYOSHI Kazuyuki SHIRAISHI Yoshikuni HIROI Mami TAKEHARA
- 出版者
- Japan Association of Mineralogical Sciences
- 雑誌
- Journal of Mineralogical and Petrological Sciences (ISSN:13456296)
- 巻号頁・発行日
- vol.111, no.2, pp.104-117, 2016 (Released:2016-05-05)
- 参考文献数
- 50
- 被引用文献数
- 2 10
U–Pb zircon geochronology was applied to nine metasedimentary samples collected from Mt. Yuzhnaya, Condon Hills, and Mt. Lira in the inland region of the Rayner Complex of western Enderby Land, East Antarctica, in order to define the eastern limits of the western Rayner Complex that underwent the Pan–African metamorphism and to evaluate potential source areas of metasedimentary rocks. Condon Hills and Mt. Lira revealed metamorphic ages of ~ 894 and ~ 934 Ma, respectively, which are consistent with previously reported metamorphism in association with Rayner Structural Episode (RSE). Mt. Yuzhnaya samples affected by the RSE contain zircon grains rejuvenated during 590–570 Ma, which indicates that the Pan–African reworking can be extended up to Mt. Yuzhnaya. On the other hand, the Condon Hills samples include Archean detritus, and the age peaks from 3850 to 2491 Ma are the oldest components in the Rayner Complex of western Enderby Land. There is no evidence of reworked Napier Complex rocks in the studied Rayner samples.