SUMMARY

Distribution if salty porewater in Holocene marine clay sediments in the Southwest of Red river Delta

Trần Thị Lựu, Phạm Quý Nhân, Trần Nghi, Flemming Larsen

In the Holocene, the information of various sedimentary facies was determined by sea level íluctuations, tectonic liữing and sedimentation rates and has been resulted in estuarine-gulf sediments, the delta and river sediments are distributed from the bottom to the top of these sediments. Using a combination of research methods including borehole geophysics, ĩield transfer methods, pore water chemical analysis, it was found that Holocene sediments still contain residual saltwater with aggregates. Based on the data of geophysical borehole logging, transient electro-magnetic soundings and the chemical composition of pore water, the distribution of fresh, brackish, and salty porewater in Holocene clay sediments in the Southwest of the Red River delta were clarified with an increasing gradually from the mainland to the sea. The results of the study also show that pore water in the sediment of the estuarine lagoon has higher total mineralization compared to the pore water of the delta. Moreover, the data of grainsize analysis, clay mineral composition of these sediments were used to reconstruct the development of Holocene sediments and explain the distribution of different porevvater types in these Holocene sediments. These data and assessments will also be used to explain the origin of saltwater in Holocene and Pleistocene aquifers.

Người biên tập: TS. Đặng Đình Phúc.