The Miyun pluton, a typical A-type rapakivi pluton, is located in the eastern North China Craton and is mainly composed of rapakivi granite and porphyric biotite granites. Zircon LA-ICPMS U-Pb dating gives that the emplacement ages of Miyun rapakivi granites are 1681 ± 10Ma and 1679 ± 10Ma, whereas, their host gneiss formed at 2521 ± 14Ma. The mean εHf(t) value of zircons from Archean gneiss is about + 4.5, indicating the protolith of gneiss was derived from a depleted mantle source. It suggests that the 2.5 Ga is an important period of crustal growth of the North China Craton. The zircons in the rapakivi granites have εHf(t) value of -5.0, indicating that the rapakivi granites were derived from a crustal source. The two-stage model ages (TDM2) of rapakivi granites are about 2.6 to 2.8 Ga, similar to those of host Archean gneisses, indicating that the rapakivi granites were derived from partial melting of the crust formed during Late Archean. The Miyun rapakivi granites were emplaced in an intra-plate extensional setting, which may be related to breakup of Paleoproterozoic Columbia supercontinent.
|Translated title of the contribution||Zircon U-Pb ages and Hf isotopes and their geological significance of the Miyun rapakivi granites from Beijing, China|
|Number of pages||12|
|Journal||Acta Petrologica Sinica|
|Publication status||Published - 2005|
- Hf isotope
- North China Craton
- U-Pb age