Zircon isotopic ages from magnetite quartzites of the Jianping metamorphiccomplex, western Liaoning Province

Using the zircon Pb evaporation method and high precise ion microprobe anal yses, zircon isotopic ages in supracrustal magnetite quartzites from Jianpi ng metamorphic complex have been obtained. The results show that the deposi tion of the supracrustal rocks occurred around 2 552-2 520 Ma and the peak of granulite facies metamorphism reached at about 2 487 Ma; about (1 806+/- 16) Ma, i.e. Mid-Proterozoic, the other possible metamorphic event with rel atively low intensity happened in the study area, It is speculated that a l ikely tectonic setting where the Jianping metamorphic complex formed is an active continental margin that is involved in continental collision and cru stal thickening shortly after its formation.