Genesis of zircon megacrysts in Cenozoic alkali basalts and the heterogeneity of subcontinental lithospheric mantle, eastern China
Genesis of zircon megacrysts in Cenozoic alkali basalts and the heterogeneity of subcontinental lithospheric mantle, eastern China
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新生代碱性玄武岩中锆石巨晶的成因及中国东部次大陆岩石圈地幔的非均质性
DOI：
10.1007/s00710-010-0120-z
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发表时间：
2010-06
影响因子：
1.8
通讯作者：
中科院分区：
文献类型：
--
作者：
在中国东部沿海的山东昌乐、福建明溪和海南蓬莱等地与新生代玄武岩有关的冲积矿床中发现了锆石巨晶。它们是无色的，透明到浅棕色-栗色，其中一些长达16毫米。昌乐、明溪和蓬莱锆石巨晶的U-Pb年龄分别为19.2 ± 0.7Ma、1.2 ± 0.1Ma和4.1 ± 0.2Ma，略大于其寄主岩石的喷发年龄（16.05- 18.87Ma、0.9- 2.2Ma和3 Ma）。昌乐、明溪和蓬莱锆石巨晶的εHf（t）值分别为9.02 ± 0.49，6.83 ± 0.47，4.46 ± 0.48，表明它们是地幔成因的。我们认为，锆石巨晶起源于交代的岩石圈地幔，后来被寄主玄武岩浆迅速带上。单颗粒内的自形形式、均匀的内部结构和化学均匀性表明在稳定条件下结晶。明显的正Ce异常和可忽略不计的Eu异常表明斜长石的氧化条件和很少或没有分离结晶。不同产地锆石巨晶Hf同位素组成的差异与其寄主玄武岩的Sr-Nd-Pb同位素组成一致。这表明寄主玄武岩的同位素特征来自于锆石巨晶所来源的岩石圈地幔。这些数据记录了中国东部上地幔的横向成分不均匀性。与地幔捕虏体一样，锆石巨晶也具有识别陆下岩石圈地幔成分和演化的潜力。
Zircon megacrysts are found in alluvial deposits associated with Cenozoic basalts from Changle in Shandong Province, Mingxi in Fujian Province and Penglai in Hainan Province within the coastal area of eastern China. They are colourless, transparent to light brown–maroon, and some of them are up to 16 mm long. U–Pb ages of zircon megacrysts from Changle, Mingxi and Penglai are 19.2 ± 0.7 Ma, 1.2 ± 0.1 Ma and 4.1 ± 0.2 Ma respectively, slightly older than the eruption ages of their corresponding host rocks (16.05–18.87 Ma, 0.9–2.2 Ma, 3 Ma). εHf(t) values of zircon megacrysts are 9.02 ± 0.49, 6.83 ± 0.47, 4.46 ± 0.48 for Changle, Mingxi and Penglai, respectively, which indicates their mantle origin. We suggest that the zircon megacrysts originated from metasomatised lithospheric mantle and were later brought up quickly by the host basaltic magma. The euhedral forms, uniform internal structure and chemical homogeneity within a single grain suggest crystallization under stable conditions. Pronounced positive Ce anomalies and negligible Eu anomalies suggest oxidizing conditions and little or no fractional crystallization of plagioclase. The differences in Hf-isotope compositions among the zircon megacrysts from different localities are consistent with the Sr-Nd-Pb isotopic compositions of their respective host basalts. This indicates that the host basalts acquired their isotopic signatures from the lithospheric mantle from which the zircon megacrysts derived. These data document the lateral compositional heterogeneity in the upper mantle beneath eastern China. Like mantle xenoliths, zircon megacrysts also have the potential to fingerprint the composition and evolution of the subcontinental lithospheric mantle.
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DOI：
10.1007/978-3-319-78527-1
发表时间：
1973
期刊：
Stable Isotope Geochemistry
影响因子：
--
作者：
J. Hoefs
通讯作者：
J. Hoefs
影响因子：
3.9
作者：
H. Zou;A. Zindler;Xi‐sheng Xu;Q. Qi
通讯作者：
H. Zou;A. Zindler;Xi‐sheng Xu;Q. Qi
影响因子：
--
作者：
R. Parrish;S. Noble
通讯作者：
R. Parrish;S. Noble
影响因子：
1.2
作者：
E. Belousova;W. Griffin;S. Shee;S. Jackson;S. O’Reilly
通讯作者：
E. Belousova;W. Griffin;S. Shee;S. Jackson;S. O’Reilly
DOI：
10.1007/bf02842210
发表时间：
1989
期刊：
Chinese Journal of Geochemistry
影响因子：
--
作者：
Wang Huifen;Yang Xuechang;Zhu Bingquan;Fan Sikun;Dai Tongmo
通讯作者：
Wang Huifen;Yang Xuechang;Zhu Bingquan;Fan Sikun;Dai Tongmo