DOI: 10.1007/s00531-016-1418-9
Scopus记录号: 2-s2.0-84992702865
论文题名: Zircon U–Pb dating of eclogite from the Qiangtang terrane, north-central Tibet: a case of metamorphic zircon with magmatic geochemical features
作者: Zhai Q.-G. ; Jahn B.-M. ; Li X.-H. ; Zhang R.-Y. ; Li Q.-L. ; Yang Y.-N. ; Wang J. ; Liu T. ; Hu P.-Y. ; Tang S.-H.
刊名: International Journal of Earth Sciences
ISSN: 14373254
出版年: 2017
卷: 106, 期: 4 起始页码: 1239
结束页码: 1255
语种: 英语
英文关键词: Eclogite
; Oceanic derivation
; Qiangtang
; Rutile
; Tibet
; U–Pb dating
; Zircon origin
Scopus关键词: argon-argon dating
; eclogite
; exhumation
; garnet
; geochemistry
; rare earth element
; rutile
; trace element
; ultrahigh pressure metamorphism
; uranium-lead dating
; zircon
; China
; Qiangtang Basin
; Xizang
英文摘要:
Zircon is probably the most important mineral used in the dating formation of high-pressure (HP) and ultrahigh-pressure (UHP) metamorphic rocks. The origin of zircon, i.e., magmatic or metamorphic, is commonly assessed by its external morphology, internal structure, mineral inclusions, Th/U ratios and trace element composition. In this study, we present an unusual case of metamorphic zircon from the Qiangtang eclogite, north-central Tibet. The zircon grains contain numerous eclogite-facies mineral inclusions, including omphacite, phengite, garnet and rutile; hence, they are clearly of metamorphic origin. However, they display features similar to common magmatic zircon, including euhedral crystal habit, high Th/U ratios and enriched heavy rare earth elements pattern. We suggest that these zircon grains formed from a different reservoir from that for garnet where no trace elements was present and trace element equilibrium between zircon and garnet was achieved. U–Pb dating of zircon gave an age of 232–237 Ma for the eclogite, and that of rutile yielded a slightly younger age of ca. 217 Ma. These ages are consistent with the reported Lu–Hf mineral isochron and phengite Ar–Ar ages. The zircon U–Pb and mineral Lu–Hf isochron ages are interpreted as the time of the peak eclogite-facies metamorphism, whereas the rutile U–Pb and phengite Ar–Ar ages represent the time of exhumation to the middle crust. Thus, the distinction between metamorphic and magmatic zircons cannot be made using only Th/U ratios and heavy REE compositions for HP–UHP metamorphic rocks of oceanic derivation. © 2016, Springer-Verlag Berlin Heidelberg.
URL: https://www.scopus.com/inward/record.uri?eid=2-s2.0-84992702865&doi=10.1007%2fs00531-016-1418-9&partnerID=40&md5=051dab58849d7494bc6c93adc01da0d7
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/70024
Appears in Collections: 影响、适应和脆弱性 气候减缓与适应
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作者单位: Institute of Geology, Chinese Academy of Geological Sciences, 26 Baiwanzhuang Road, Beijing, China; Department of Geosciences, National Taiwan University, Taipei, Taiwan; Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
Recommended Citation:
Zhai Q.-G.,Jahn B.-M.,Li X.-H.,et al. Zircon U–Pb dating of eclogite from the Qiangtang terrane, north-central Tibet: a case of metamorphic zircon with magmatic geochemical features[J]. International Journal of Earth Sciences,2017-01-01,106(4)