The zircon was dated by using the technique of single-zircon stepwise evaporation-deposition with a thermal ion mass spectrometry (Bernd Kober, 1986 and 1987). The zircon ages are 2.60-2.54 Ga for biotite-leptynite (BL), 3.36-2.62 for mimatized leptite (ML), and 3.53-3.08 Ga for quartzite(Q) from the iron formation. Combined with available data, it is comidered that the sourcerock of biotite--leptynite might be intermediate-acid volcanic material of ca.2.7 Ga, and that of migmatized leptite and quartzite might come from granitic crust older than 3.0 Ga. The iron formation was formed on the continental crust base at about 2.7 Ga, and was immediately metamorphosed for the first time.