Ban Giang Fm

Period:

Devonian

Age Interval:

Emsian-Eifelian, D₁-D₂ebg, ( 18)

Province:
North Trung Bo

Type Locality and Naming

Upper formation of Hon Son Gr. The section extends along Rao Chan Stream, where the stream passes Ban Giang Village (Chuc A area, Huong Khe District, Ha Tinh Province) (N = 18° 04‘; E = 105° 42’).

Synonym: Điệp Bán Giàng: Trail Tính et al. 1979, Nguyễn Đức Khoa el al. 1981; Nguyễn Quang Trung et al. 1983; Nguyền Văn Hoành, Phạm Huy Thông 1984; Nguyễn Đức Khoa 1984; Tống Duy Thanh et al. 1986, 1988 (D₁ -D₂e); Vũ Khúc, Bùi Phú Mỹ et al. 1990 (D₂C); Nguyễn Đức Khoa, Nguyễn Hữu Hùng et al. 1995 (Hệ tầng); Tống Duy Thanh, Nguyễn Đức Khoa 2000 (Hệ tàng); Phạm Huy Thông 2001 (I lệ tầng - Emsian - Eifelian), Tống Duy Thanh 1993 (Fm - D 1.2). Bậc Ei/el (part): Mareichev A.M. và Tràn Đức Lương (Dovjikov A.E. et al. 1965). Hệ tầng La Trọng'. Dương Xuân Hào el al. 1973, 1975 (D₂e). Các trầm tích Eifel (part): Dương Xuân Hào (Trần Văn Trị et al. 1977). Điệp Rào Chan (part): Nguyễn Quang Trung 1983 (D₁). Hệ tầng Lý ỉỉoà (part.): Phạm Huy Thông, Tạ Hoà Phương, Nguyễn Hữu Hùng, Đoàn Nhật Trưởng 1999

Lithology and Thickness

Sandstone: (1). Sandstone and siltstone interbeds containing coral Calceola sandalina, brachiopods Stropheodonta sp., Howellella sp., 190 m thick. (2). Quarzitic quartz sandstone containing crinoids, 135 m thick. (3). Thin-bedded sandstone containing poorly preserved remains of brachiopods, gastropods, 240 m thick. (4). Quarzitic quartz sandstone, in the upper part there is some calcareous clayey shale containing the brachiopods Chonetes sp., Atrypa sp., Desquamatia cf. kurbesekỉana, D. cf. lanceoides, 170 m thick. The total thickness of the section reaches 735 m,

Lithology Pattern:

Sandstone

Relationships and Distribution

Lower contact

A conformable contact with the underlying Rao Chan Fm is exposed in most sections

Upper contact

Conformable with the overlying Muc Bai Fm.

Regional extent

The Ban Giang Fm occurs mainly in Ha Tinh and Quang Binh Provinces; in Ha Tinh it is exposed in the Chuc A area in NW - SE bands 4 - 5km width and 40 - 50k length, in Quang Binh Province the formation is well exposed in Quy Dat, Thanh Lang, Dai Du areas on both flanks of the NW - SE synclinc from Thanh Lang (Minh Hoa District) to Rao Troc (Bo Trach District).

GeoJSON

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Fossils

Gephuropora vietnamica, Thamnopora nicholsoni, Th. squameosepta, Cladopora gracilis, Parastriatopora cf. dobreizovi, Crassiaiveolites cf. multiperjoralus; Heliolites cf. pororus, Paraheliolites cf. hanusi, Thamnophyllum khelopense, Sociophyllum aff. sociale, Beugnisastrea aff. parvistella (= Spongophyllum halisitoides), Pseudogrypophyllum stenotabulatum, Stringophyllum sp.; Stromatopora hupschii, Amphipora sp., Stachyodes sp.

[Figure: Bản Giàng Fm: Corals Calceola sp. (images courtesy of Prof. Ta Hoa Phuong, Vietnam Natl. Univ. Hanoi)]

Age

Emsian to Eifelian (late Early Devonian to early Middle Devonian)

Age Span:

Beginning stage:

Emsian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

410.51

Ending stage:

Eifelian

Fraction up in the ending stage:

1.0

Ending date (Ma):

385.30

Depositional setting

Depositional pattern:

Additional Information

Compiler:

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).