Differential exhumation and cooling history of North Qaidam UHP metamorphic rocks, NW China: Constraints from zircon and rutile thermometry and U-Pb geochronology

Zhang, Guibin, Zhang, Lifei, Christy, Andrew G., Song, Shuguang and Li, Qiuli (2014) Differential exhumation and cooling history of North Qaidam UHP metamorphic rocks, NW China: Constraints from zircon and rutile thermometry and U-Pb geochronology. Lithos, 205 15-27. doi:10.1016/j.lithos.2014.06.018


Author Zhang, Guibin
Zhang, Lifei
Christy, Andrew G.
Song, Shuguang
Li, Qiuli
Title Differential exhumation and cooling history of North Qaidam UHP metamorphic rocks, NW China: Constraints from zircon and rutile thermometry and U-Pb geochronology
Journal name Lithos   Check publisher's open access policy
ISSN 0024-4937
1872-6143
Publication date 2014-09-15
Year available 2014
Sub-type Article (original research)
DOI 10.1016/j.lithos.2014.06.018
Open Access Status Not yet assessed
Volume 205
Start page 15
End page 27
Total pages 13
Place of publication Amsterdam, Netherlands
Publisher Elsevier BV
Language eng
Subject 1906 Geochemistry and Petrology
Abstract We analyze zircon and rutile U-Pb ages and trace elements using LA-ICP-MS and SIMS of eclogites from the North Qaidam ultra-high-pressure metamorphic belt in NW China. Zr-in-rutile and Ti-in-zircon thermometries give consistent peak metamorphic temperatures for two fresh eclogite samples. Zircon and rutile U-Pb dating from the Yuka eclogite yielded ages of 430.2±3.7Ma and 407±16Ma respectively. Zircons from North Dulan eclogite record two distinct eclogite-facies metamorphic events at 446.6±4.1 and 430.5±4.7Ma, with TTi-in-zircon=684±16°C and 649±26°C respectively, while rutile U-Pb dating for the same North Dulan eclogite sample yielded an age of 416±10Ma. These rutile U-Pb ages are interpreted to record the time when these rocks cooled down to the closure temperature of Pb in rutile (here, taken to be ca. 570°C). Thus, we obtain a slow cooling rate of ~3-4°C/Ma for Yuka and North Dulan terranes. For one granulite-facies overprinted South Dulan eclogite sample, rutile U-Pb dating gave a younger age of 383±10Ma. Combined with literature chronological and temperature data for South Dulan, the data imply later exhumation than the other samples with a faster cooling rate of ~6.6°C/Ma, after the granulite-facies event. The T-t paths obtained show that the North Qaidam eclogites experienced considerably slower cooling history than previously assumed, and also that while the thermal histories of the Yuka and North Dulan eclogites resemble one another, the South Dulan eclogite is quite distinct. So, a differential exhumation and emplacement of UHP metamorphic rocks occurred in the North Qaidam.
Keyword Eclogite
North Qaidam
Rutile U-Pb geochronology
Ti-in-zircon thermometry
Zircon U-Pb geochronology
Zr-in-rutile thermometry
Q-Index Code C1
Q-Index Status Provisional Code
Grant ID 41272068
NCET-13-0017
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Earth Sciences Publications
 
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