Abstract

Holocene sediments are largely distributed in plain area of the lower course of the Thu Bồn - Vu Gia River. The analysis and synthesis of drilling materials carried out in the studied area have been showing that the lower part of these sediments is composed of sand, silt, clay and peat, expressing the marshy state of this locality. The middle part consists of marine formations, including mainly fine-grained beds (silt and clay) of littoral and lagoonal facies grading upward into mainly coarse-grained beds of continental facies. These lower and middle parts form a continuous section developed in a gradual transition from the marshy state to a sea transgression into the area. The upper part is composed of coarse-fine-coarse beds expressing a process of sea regression from the area. Holocene sediments of the studied area have been described as formations of different facies of the following ages: Early-Middle Holocene (Q₂^1-2), Middle-Late Holocene (Q₂^2-3), Late Holocene, early part (Q₂³⁽¹⁾) and Late Holocene, late part (Q₂³⁽²⁾).