Терригенное лавинное осадконакопление на примере пермских толщ Охотского и Аян-Юряхского бассейнов (Северо-Восток Азии)

Abstract

Terrigenous avalanche sedimentation in Northeast Asia is considered on the example of the Permian strata of the Okhotsk and Ayan-Yuryakh basins. These deposits form a complicated sedimentary complex undergoing regular changes in the direction from the southwest (from the Okhotsk massif) to the northeast (to the Ayan-Yuryakh anticlinorium) - from continental and coastal-marine environments to deep-water, corresponding to the conditions of the foot of the continental slope. An important specific feature of this basins is the widespread development of deep-water deposits, primarily of various types of gravitites, among which facies of proximal and distal turbidites, grain and clay flows, and diamictites (debrites) can be distinguished. The facies of nepheloidites and disturbed-bedded deep-water siltstones also play a significant role. Shallower sediments are less widespread and were formed within the shelf of the Okhotsk massif. They are represented by facies of coastal sandstones, sandstones and siltstones of the inner part of the shelf and siltstones of the outer part of the shelf. Almost all types of rocks contain one or another fraction of pyroclastic material, the amount of which increases with approaching the Okhotsk massif, where some probable centers of eruptions of the Okhotsk-Taigonos volcanic arc were located. In the evolution of the basins under consideration, the general stages in the development of the entire system of northeast Asian basins are clearly established, which was obviously determined by reasons of a global scale. The first three stages correspond to the regional superhorizons (Munugudzhakian, Dzhigdalian, and Omolonian), the last three, to the Gizhigian Horizon and subhorizons of the Khivachian Horizon).