AGE OF THE STANOVOY COMPLEX OF EAST SIBERIA: EVIDENCE FROM SHRIMP II ION MICROPROBE DATA

Abstract

Gniesses, crystalline schists, migmatites, and granite gneisses of the Stanovoy Complex compose much of the Dzhugdzhur–Stanovoy Foldbelt (DSFB), which is separated from the Aldan Shield by the Stanovoy collisional suture and extends from the Nyukzhi River in the west to the Sea of Okhotsk in the east. In the south, it is bounded by the Mongolia–Okhotsk belt. The Stanovoy Complex is traditionally attributed to the Late Archean without any isotope–geochronological evidence. However, recently we have obtained a great amount of convincing data indicating that not only allochthonous granitoids, which are widespread in the study region and were previously regarded as Early Proterozoic formations , but also large massifs of late Stanovoy granites, are of Mesozoic age (138–142 Ma). The Archean date (2835 Ma) was only obtained for the Stanovoy granites from the Dambukin block (central DSFB) metamorphosed under granulite facies at about 2700 Ma.