TrÇn Ngäc Nam, Y. Sano, S. L. Chung

Zircons from the Ca VÞnh Complex have been dated by SHRIMP U-Pb method to establish the protolith ages of the complex. Almost SHRIMP U-Pb zircon analyses for two samples RR03 and RR09 from the Ca VÞnh Complex yield concordant ages clustering at 2840 Ma, generally consistent with previously reported 2900 Ma dates of HK22 zircon cores from the complex. These ages strongly indicate the Late Archean age for the protolith of the Ca VÞnh complex. Another analyses give younger U-Pb ages of ca. 2400 Ma and 2000 Ma, corresponding to dates of two later high-grade metamorphic events affecting the complex during the early Proterozoic times.