Раннемеловые растительные сообщества и палеообстановки на полуострове Муравьева-Амурского (Дальний Восток, Россия)

Remains of Barremian-Albian plants (Lower Cretaceous, Nikan Group) were studied from the Ussuri, Lipovtsy, and Galenka formations on the Muravyov-Amursky Peninsula, part of the Razdol'naya B asin. The age of the Nikan Group of the basin has been substantiated by paleobotanical, palynological data and U-Pb isotope dating of detrital zircons. The Nikan flora of the Muravyov-Amursky Peninsula consists of approximately 125 taxa, embracing a variety of ferns and gymnosperms, as well as rare angiosperms. This flora is represented by three floral assemblages (FAs): Ussuri (Barremian), dominated by ferns and conifers; Lipovtsy (Aptian - Early Albian), with prevalence of ferns, cycadophytes, conifers and the first appearance of angiosperms; and Galenka (Early to Middle Albian), where ferns and conifers predominate, and also rare angiosperms are constantly present. The Barremian-Albian sedimentation paleoenvironments on the Podgorodnenka depression are discussed: the foothill alluvial-accumulative plain (Barremian) was replaced by a coastal-alluvial swampy plain (mainly Aptian, beginning of the Early Albian) and later transformed into a lacustrine-alluvial plain (Early to Middle Albian).