Late Mesozoic rifting at the flanks of the Dzhagda segment of the Mongolia-Okhotsk collisional orogen: global and regional aspects

• Published in: Geodynamics & Tectonophysics
• Main Author: G. L. Kirillova
• Format: Article in Journal/Newspaper
• Language: English; Russian
• Published: Russian Academy of Sciences, Siberian Branch, Institute of the Earth's crust 2017
• Subjects: rifting; late mesozoic; stratigraphy; volcanism; mongolia-okhotsk collisional orogen; uda and nora-selemdzha foreland basins; the far east of russia; Science; Q; Okhotsk; Pacific; Yakutia
• Online Access: https://doi.org/10.5800/GT-2017-8-1-0236; https://doaj.org/article/8b3115bf507448f5aac3414447dbd347

The role of rifting in the formation of the recent structure of the Mongolia-Okhotsk orogen is extremely high, but it is still underestimated with regard to flanks of the Dzhagda segment of this orogen. Current researches refer to a combination of physical and chemical processes in the depth of the lithosphere, as well as interactions between the Izanagi, Eurasian and Pacific plates as explanations of repeated rifting events in East Asia. Upwelling of the asthenosphere due to significant differences in the lithosphere thickness (150–200 km under cratons, and only 100 km under orogenic belts) was viewed as a cause of rifting. It was assumed that rifting was controlled by mantle plumes, volcanism and heat regime. Structures bordering the Mongolia-Okhotsk orogen from north and south were considered as superimposed or marginal troughs. Recent studies have revealed numerous riftogenic Late Mesozoic structures in the Central Asian orogenic belt, which resulted from the collision of the Siberian and North Chinese cratons. New geological survey and geochemical data on volcanites confirmed the riftogenic origin of the Zeya-Uda (or Uda) and Nora-Selemdzha troughs bordering the Mongolia-Okhotsk orogen from north and south, respectively (Fig. 1, and 2). Geology and geophysics of those troughs has been described. It is noted that riftogenic volcanites formed later in the east than those in the west. The Late Mesozoic rifting is widely manifested in North Eastern Asia across the area exceeding two million square kilometers, from Lake Baikal to the Sikhote-Alin region (west to east) and from the Southern Yakutia basins to North China (north to south). It is evidenced by intra-continental rifts of various trends, volcanic provinces and extension structures along large strike-slip faults [Renet al., 2002]. The Uda and Nora-Selemdzha marginal troughs located along the Dzhagda segment of the Mongolia-Okhotsk orogen give evidence that compression was replaced by extension in the study area. Rifting structures may be due to physical ...