Yakchi chert–volcanogenic Formation—fragment of the Jurassic accretionary prism in the Central Sikhote-Аlin, Russian Far East

Researchers have identified the Yakchi chert–volcanogenic formation as a critical fragment of the Jurassic accretionary prism in the Central Sikhote-Alin, providing insights into the tectonic and oceanic history of this region. The study, which combines biostratigraphic analysis and petrogeochemical investigations, reveals that the formation spans from the Late Triassic to the Middle Jurassic, with distinct phases of chert accumulation interrupted by basalt eruptions. These basalts likely formed on both thick, old oceanic lithosphere (Middle–Late Triassic) and thin, newly created lithosphere (Jurassic). The transition from chert to tuffaceous siltstone in the Middle Jurassic marks the onset of subduction along the Asian continental margin, predating the accretion of this formation. This work clarifies the paleotectonic zonation of the Central Sikhote-Alin and suggests that cataclastic gabbroids and granitoids may be analogues of the Okrainka-Sergeevka allochthonous complex.

Zyabrev, S. V., Voinova, I. P., Martynyuk, M. V., & Shevelev, E. K. (2016). Yakchi chert–volcanogenic Formation—fragment of the Jurassic accretionary prism in the Central Sikhote-Аlin, Russian Far East. Russian Journal of Pacific Geology, 10(5), 365–385. https://doi.org/10.1134/s1819714016050067