Late Paleozoic flora assemblage (Cathaysia flora) in Vietnam and surrounding areas

Nghiêm Nhật Mai, Nguyễn Đức Phong, Nguyễn Hữu Mạnh

The Cathaysia flora has been named for the one developed during the Carboniferous - Permian in Asian lands, such as China, Korea, Japan, Viet Nam, Laos, Thailand, Malaysia and Indonesia.

During the Early Carboniferous time this flora also contains the elements of Euramerica flora (The Flora developed in the tropical, hot and humid climate condition) and it is supposed to be originated and developed from the global uniform Lepidodendropsis flora of Early Carboniferous. The Cathaysia flora is divided into two floral sub-provinces distributed in the North and the South China. The tectonic evolution, climatic differentiation, oceanic circulation, palaeogeographycal environment etc. are the causes for the evolution of the organism. Concerning with the above mentioned problems of Southeast Asia have been documented. A mixed flora of southern hemisphere and northern hemisphere (Gondwana and Cathaysia) that flourished in the Late Permian period (Wuchiapingian- Changhsingian). After Late Permian mass extinction, the descendants of the mixing Cathaysia flora continue to develop and became a characteristic mixed Late Triassic Norian- Rhaetian flora. This flora is present in many parts of the western margin of the Pacific Ocean, including Ḥn Gai flora of Vietnam.

Key words: Early Carboniferous, Late Permian, Cathaysia flora, pantropical, mixed flora, Ḥn Gai flora