Vinh Bao Fm

Period:

Neogene

Age Interval:

Pliocene, N₂, (12, 13)

Province:

Vietnam Offshore North, West Bac Bo

Type Locality and Naming

Hanoi Depression and North Song Hong Basin (north Red River Basin). The type section is located borehole GK.3 drilled at Vinh Bao, Hai Phong City from 240 to 510 m (N = 20°40’; E = 106°38’).

Synonym: Hệ tầng Vĩnh Bảo: Golovcnok V.K., Lê Văn Chân 1966; Golovenok V.K., Kisliakov V.N. 1970; Trịnh Dánh(in Vũ Khúc et al. 2000). Điệp Vĩnh Bào: Skorduli V. D. 1983; Trịnh Dánh 1975, 1979, 1995; Phạm Hồng Quế 1981; Lê Văn Cự 1987;ĐỖ Bạt, Phan Huy Quynh 1984, 1986, 1993, 2000; IDEMITSU 1994.

Pliocene: TOTAL 1991. Hệ tầng Biển Đổng: Phan Trung Dicn 2000.

Lithology and Thickness

The formation can be divided into 2 parts: Lower part is mainly composed of grey to yellowish, thick- bedded, well-sorted sandstone, locally with lenses or interbeds of small pebble conglomerate and gritstone. Upper part is siltstone with interbeds of sandstone. The thickness of the formation in this borehole reaches 270 m. These sediments yield many marine fossils, such as molluscs, foraminifera and corals.

Lithology Pattern:

Fine-grained sandstone

Relationships and Distribution

Lower contact

Unconformity upon the Tien Hung Fm has been well observed.

Upper contact

Quaternary

Regional extent

Late Tertiary transgression into the north Red River Basin

GeoJSON

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Fossils

Giobigerina bulloides (N5-N20), Gl. nepenthes (N14-N19), Globigerinoides ruber (N18-N23), Cdes congỉobatus (N18-N23).

Age

Pliocene.

Age Span:

Beginning stage:

Zanclean

Fraction up in beginning stage:

0.0

Beginning date (Ma):

5.34

Ending stage:

Piacenzian

Fraction up in the ending stage:

1.0

Ending date (Ma):

2.58

Depositional setting

Deltaic and shallow sea. Major deltas filling offshore basin.

Depositional pattern:

Additional Information

Compiler:

Discussion notes from Prof. Tran Nghi (2019); Tran Van Tri and Vu Khuc (Editors; Geology and Earth Resources of Viet Nam, General Dept. of Geology and Minerals of Viet Nam; completed in Dec., 2011), with additional details from Tong-Dzuy Thanh and Vu Khuc (Editors; Stratigraphic Units of Viet Nam, 2^nd edition; 2011; English edited by A. Boucot).