FIRST SM-ND DATA ON LATE ORDOVICIAN AGE OF GRANITOIDS OF THE VERKHNYAYA MAYA UPLIFT, OKHOTSK MASSIF

Abstract

The Verkhnyaya Maya Uplift (VMU), which extends from upper reaches of the Maya River along its left bank to the Inikan River in the eastern part of the Yudoma-Maya Highland, is restricted to the complex junction of geostructural elements of different types and ages. It separates the Yudoma-Maya trough and South Verkhoyansk synclinorium from the Okhotsk Massif on the west and from the Ul'in volcanogenic trough on the east. The VMU is a NE-extending wedgeshaped tectonic block (20 × 130 km) of granitoids of the Maya Complex and metamorphic rocks of the Verkhnyaya Maya Group, which significantly differ from the host rocks in composition, metamorphic grade, folding, and age (Fig. 1). The VMU has been poorly studied in terms of geophysics and geology. Therfore, the main problems of its geology and tectonic position remain highly controversial. The alternative interpretations are based on geosynclinal or plate tectonic concepts [6-8]. The age data presented in this paper indicate that tectonomagmatic evolution of this region ceased in Early Paleozoic (Late Ordovician).