Interpretation of depositional environments of the Tertiary sedimentary rocks in

Hạ Long area, Quảng Ninh

Hoàng Văn Long

The Tertiary sedimentary rocks in Hạ Long are distributed eratically as narrow belts and were considered to be corresponding to the sedimentary rocks in the oil and gas- bearing Tertiary basins in continental shelf of Việt Nam.

Based on the integration and processing of the lithological, grain-size and paleontological data together with detail stratigraphic mapping and field observation, the Tertiary sedimentary formations in Hạ Long were subdivided into four major lithofacies and corresponding depositional environments: (1) fluvial-channel cross­bedding sandstone; (2) fluvial-plain coal-bearing mudstone; (3) point-bar fining-upward gravelly-sandstone; and (4) lacustrine organic-rich shale. The results derived from lithofacies, depositional environment and regional tectonic studies showed that the research area has been strongly affected by the Neotectonic activities, which are mainly characterized by brittle and extensional deformation together with regional strike-slip motion.

Người biên tập: GS. TS Trần Văn Trị; TS. Phạm Đ́nh Thọ.