The Stages of Formation of the Main Batholite Belt, Northeast Russia: U-Th-Pb SIMS and Ar-Ar Geochronological Data

摘要

The original and published geochronological data and the geological position of different granitoid complexes of the Main (Kolyma) Batholith Belt of Northeast Asia have been generalized. It was proved that the belt was formed in two stages. The first Late Jurassic stage of magma generation of granitoids of the Kolyma complex resulted from the collision of island arc and cratonic terranes. This stage was ended with amalgamation of the Kolyma-Omolon superterrane (microcontinent), which is reflected in the U-Pb dating of zircons from granitoids (155-147 Ma). The second, main, stage of the collision of the Siberian continent and the Kolyma-Omolon microcontinent occurred at the boundary between the Jurassic and the Cretaceous. During this stage, intrusions of the Kolyma complex were developed at the upper horizons of the crust, which was proved by the Ar-Ar age estimation (146-133 Ma). The melting out of granitoids of the Nel'kan, Baky-Derbekin, Sakhan'ya, and Omchikandya complexes of the Main Belt with the Early Cretaceous dating for zircon (145-130 Ma) is related to this stage.