THE YANA-KOLYMA FOLDBELT AS AN EXAMPLE OF SHALLOW ERODED COLLISIONAL STRUCTURE IN NORTHEAST ASIA

The Yana-Kolyma folded belt represents an area of intense folding, penetrated by numerous plutons of diverse composition, various forms and sizes. It is referred to as the Yana-Kolyma collisional zone [Goryachev, 1995]. It marks the area of collision-originated structures of the Indigirka-Omolon (Kolyma-Omolon) super-terrane with pas-sive margin of the Siberian continent in Late Jurassic [Tectonics …, 2001; Shpikerman, 1998]. The zone consists of two parallel large linear structures: anticlinorium (southwest) mainly consisting of Permian and Triassic sequences (Adycha-El’ga – Ayan-Yuryakh), and synclinorium (northeast) composed of sediments of the Triassic- Jurassic age (Inyali-Debin). Within the belt the sedimentary cross-section of rocks is continuous, excluding only local uncorformity [Geology of the USSR, 1970; Chekhov, 1976; 1990; Geology..., 1981; Tectonics …, 2001]. Sedimentary sequences consists of alternated sandstones, aleurolites, clay and carbon-clay shales, rarely conglomerates and layers of limestones. They were derived in the settings of continental slope or its bottom and are attributed to turbidites [Berger, 1990]. Sedimentary rocks are sheared in intensive linear, crest-like and sometimes recumbent folds of northwestern trending [Chekhov, 1976]. These folds ar