SUMMARY

Study on the evolutional process during the Quaternary of the Red River Valley section in the Phú Thọ Province
by the research on characteristics and distribution of loose sediments

Phạm Đình Thọ, Nguyễn Địch Dỹ, Đặng Văn Bát, Hạ Văn Hải

Through its long evolutional history since pre-Quaternary, the Red River current displaced many times. One of its traces is the system of loose alluvial materials, lacustrine-marshy sediments and traces of different Quaternary terraces. In the Red River Valley, Quaternary sediments have the age of from Early Pleistocene to Holocene and are distributed in different altitude. The structure of Quaternary stratigraphic units includes mainly 2 parts, with the lower composed of coarse-grained deposits of river-bed facies, the upper part – fine-grained deposits of alluvial-flat facies. The history of current change of the Red River in the study area has been re-established on the basis of study on characteristics and distribution of the Quaternary stratigraphic units. At the beginning of the Quaternary, the Red River was composed of two main branches. The first branch flowed in the northeast through Liên Phương, Đại Phạm, Lương Bằng, and the second – in the southwest through Tiên Mỹ, Mỹ Lương, Yên Lập to Thanh Sơn. Further, the activity confines of the Red River in Phú Thọ was more and more narrowed; the northeastern branch gradually displaced towards southwest, on the contrary the southwestern branch – towards northeast, and the Red River Valley narrowed gradually as at the present time.

Người biên tập: Hoàng Anh Khiển.