In recent years, the exploration and exploitation of oil and gas have been widely carried out in the continental shelf of Southwest ViÖt Nam (on the northeastern margin of the M· Lai – Thæ Chu basin).

Basing on the research and collection of materials on lithostratigraphy, biostratigraphy and sequence stratigraphy taken from drilling wells and seismic sections, the authors have established the stratigraphic columns for the entire region. Especially, it is the first time the following new lithostratigraphic units was described:

- Kim Long Formation (Oligocene);

- Ngäc HiÓn Formation (Lower Miocene);

- §Çm D¬i Formation (Middle Miocene);

- Minh H¶i Formation (Upper Miocene); and the BiÓn §«ng Formation (Pliocene - Quaternary) was found in this basin.

The petroleum shows are related to the Oligocene and Lower-Middle Miocene sediments.