SIMS U-Pb Ages of Zircon and Tectonic Significance of Taihua Metamorphic Complex in the Eastern Luoning, the Southern Terminal of Trans-North China Orogen(PDF)
《地球科学与环境学报》[ISSN:1672-6561/CN:61-1423/P]
- Issue:
- 2016年第06期
- Page:
- 822-834
- Research Field:
- 基础地质与矿产地质
- Publishing date:
Info
- Title:
- SIMS U-Pb Ages of Zircon and Tectonic Significance of Taihua Metamorphic Complex in the Eastern Luoning, the Southern Terminal of Trans-North China Orogen
- Author(s):
- CHEN Hong-xu; WANG Hao; PENG Tao; ZHANG Hui; WU Chun-ming
- College of Earth Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
- Keywords:
- geochronology; Taihua metamorphic complex; amphibolitic gneiss; felsic gneiss; SIMS zircon U-Pb age; tectono-metamorphic event; Trans-North China Orogen
- PACS:
- P597
- DOI:
- -
- Abstract:
- Located in the southern terminal of the Palaeoproterozoic Trans-North China Orogen (TNCO), garnet-bearing felsic and amphibolitic gneisses in the eastern Luoning terrane within the nearly EW-striking Taihua metamorphic complex, preserve three generations of metamorphic mineral assemblages, i.e., the prograde, peak and retrograde metamorphic stages. The prograde assemblages (M1) comprise of hornblende+plagioclase+quartz inclusions preserved in the garnet porphyroblasts. The metamorphic peak assemblages (M2) are represented by the garnet porphyroblasts as well as the matrix minerals (plagioclase+hornblende+ quartz+zircon±biotite±K-feldspar). The retrograde assemblages (M3) are the finegrained “white-eye socket” symplectitic assemblages formed between the relict garnet porphyroblasts and the adjacent matrix minerals, consisting of plagioclase+hornblende+quartz. In order to complement our previous research, SIMS U-Pb dating results of zircons separated from the felsic and amphibolitic gneisses are reported here, which show that (a) the Luoning complex records two magmatic episodes (2.32-2.33 Ga and 2.18 Ga), suggesting that the southernmost terminal of the TNCO is also involved in the crust reworking; and (b) the peak metamorphic event took place at 1.94-1.95 Ga in the Luoning complex, implying that the Precambrian metamorphism of the Luoning Taihua complex not only occurs earlier (~100 Ma) than, but also lasts longer than that of most of the other metamorphic terranes within the middle and northern TNCO. Combined with the literature data concerning the different discrete terranes within the TNCO, it is therefore certified that the tectono-metamorphic event of the Palaeoproterozoic TNCO is a long and complex history.
Last Update: 2016-12-01