北桐柏地区镁铁质麻粒岩锆石U-Pb年代学及变质作用

Translated title of the contribution: Zircon U-Pb geochronology and metamorphism of mafic granulite from north Tongbai, central China

Hua Xiang*, Li Zhang, Zeng Qiu Zhong, Hong Fei Zhang, Jian Ping Zheng, Li Liu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)

Abstract

LA-ICP-MS U-Pb dating of metamorphic zircons from mafic granulite in northern Tongbai area yielded weighted mean 206PbZ238U concordia age of 418. 7 ±3. 2Ma. Detailed studies on petrology and mineralogy of the mafic granulites indicate that the peak metamorphic condition was at ca. 845°C and ca. 0. 85GPa. According to the Zr saturation model, Zr was not saturated in melts at peak metamorphic condition and would be saturated when cooling to 750∼800°C, calculated by partial melting modeling. Additionally, Ti-in-zircon geothermometer also gives the crystallization temperature of ca. 75°C. These are suggested that the age of 418. 7Ma is not the age of peak metamorphic condition, and probably is a record for the time when cooling to 750 ∼ 800 °C. The age of peak metamorphism could be around 430 ∼445Ma. Some zircon grains have obvious overgrown rims, with stronger cathodoluminescence and higher common Pb than the core. The rims and high common Pb zircons domain yield a age of 404. 7 ± 6. 5Ma, indicating that the mafic granulite suffered a retrograde metamorphism at about 404Ma We suggest that the high-temperature mafic granulites from north Tongbai were probably formed in residual overthickened crustal basement in continental subduction collision zones or arc continent collision belts.

Translated title of the contributionZircon U-Pb geochronology and metamorphism of mafic granulite from north Tongbai, central China
Original languageChinese
Pages (from-to)348-358
Number of pages11
JournalActa Petrologica Sinica
Volume25
Issue number2
Publication statusPublished - 2009
Externally publishedYes

Keywords

  • Mafic granulite
  • Metamorphism
  • Northern tongbai
  • Zircon U-Pb dating

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