- 责任者：Wu Tao (Faculty of Earth Sciences ; China University of Geosciences ; Wuhan 430074 ; China) ; Xiao Long
- 刊名：Acta Petrologica Sinica
- 出版年：2013
- 卷期：29(10)
- 关键词：杂岩 ; complexes ; 锶同位素 ; strontium isotopes ; 钕同位素 ; neodymium isotopes ; 西藏 ; Tibet
- 页码：p.3567-3580
- 图表：9 illus., 3 tables, 44 refs.
- 分类号：0801
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
Tongpu intrusive complex, located in eastern Tibet, consisting of biotite granite, porphyritic granite, granodiorite and quartz diorite, in this paper, we report detailed petrography, zircon U-Pb ages, whole-rock major and trace elements, Sr-Nd isotopic compositions of the Tongpu intrusive complex. The results suggest that the biotite granite, granodiorite and quartz diorite formed at the similar time with crystallization ages 263.7 ± 1.6Ma, 263.9 ± 1.9Ma, 262. 8 ± 1.5Ma, respectively. Biotite granites, porphyritic granites and granodiorites contain high SiO2 （65.1% ～76. 6% ） and K20 ± Na20 （4. 84% ～8.13% ） contents but low MgO （0. 25% ～ 2. 28% ） and FeOT （0. 99% ～ 4. 44% ） contents. They also have high A/CNK values （ mainly from 1.15 to 1.51 ） and depleted Ba, Sr and Eu contents, which are comparable to the strongly peraluminous S-type granites. However, CaO/N%0, Rb/Ba and Rb/Sr ratios of them are significantly different, and they also show no correlation in Hark variation diagrams, suggesting that they have different source regions. On the other hand, the quartz diorites exhibit low SiO2 （54. 2% ～ 55.4% ） and K2O ± N%O （3. 15% ～ 4. 72% ） contents but high MgO （3.78% ～4. 79% ） and FeOT（6. 13% ～8. 09% ） contents. They show arc affinity with depleted Nb, enriched in LREE compare to HREE and no Sr anomaly. In terms of isotopic compositions, porphyritic granite and granodiorite have high initial S7Sr/Srsr ratios （0. 7099 and 0. 7125, respectively） and negative εNO （t） （ - 8. 6 and ～ 10. 3, respectively）, consistent with the S-type granites and high-SiO2 rhyolite of our research area. However, quartz diorite has low initial STSr/SrSr ratios （0. 7062） and positive εnd （t） （1. 37 ）, which resembles the Jinshajiang MORB field. Therefore, we suggest that Tongpu intrusive complex was formed under volcanic arc setting. The four rock types of it have different source regions： biotite granite, porphyritic granite and granodiorite were derived from partial melting of crust materials mainly of pelite and greywacke, respectively while quartz diorite was derived from the enriched mantle. Our research also suggested that the Jinshajiang ocean was still under a subducted setting at the early stage of Late Permian.