The system of Cenozoic depressions in the Amur and Primorye regions: The structure, tectonic position, and geodynamic interpretation

Author： Perestoronin A. Razvozzhaeva E.

Publisher： MAIK Nauka/Interperiodica

ISSN： 1819-7140

Source： Russian Journal of Pacific Geology, Vol.5, Iss.2, 2011-04, pp. : 139-154

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Abstract

The analysis and synthesis of the seismic data, the local gravity field, and the geological evidence reveal that the faults representing a framework for a system of the Cenozoic depressions in the Amur and Primorye regions define various structural parageneses: en echelon sets, extension duplexes, and conjugate knots. Being regularly arranged, they form a single branched-reticulate regional disjunctive zone named the Ussuri-Okhotsk rifting zone (UORZ). Owing to the relation with the faults of the Tan-Lu system and the graben-shaped basins of the marginal seas, this zone is an element of the pericontinental zigzag lineament zone, which controls the East Asian graben belt. The Ussuri-Okhotsk rifting zone represents a wide incipient right-lateral transtensional zone, which was formed under conditions of a pure shear deformation accompanied with additional extension. The compression and extension axes were oriented in the northeastern and northwestern directions, respectively. This deformation was responsible for passive dispersed epiorogenic and epiplatform rifting. After the episode of Late Miocene tectonic inversion, the rifting acquired taphrogenesis features. The tectonic movements were largely confined to extended deep-seated faults and led to the formation of spacious two-stage depressions. Simultaneously, the role of active rifting substantially increased, which is evident from the development of numerous Neogene-Quaternary basaltic plateaus. The rifting became more intense to form larger depressions reflecting deeper endogenic processes. This could probably be related to the mantle magmatism, the regional consolidation of the crust, changes in its structural anisotropy, and the insignificant reorganization of the tectonic stress field.