Trang Kenh Fm

Period:

Devonian

Age Interval:

Middle-Late Devonian; D₂ –D₃tk, (5)

Province:
East Bac Bo

Type Locality and Naming

Lower formation of the Thuy Nguyen Gr (both inland and coastal-offshore). In the Trang Kenh area, the beds of the Fm are exposed in My Due Townlet (Trang Kenh) and in the northern bank of the Song Thai River.

Synonym: Tầng Tràng Kênh: Nguyen Quang 1 1ập 1967 (Eifelian-Givetian). Anthracolile (part.): Patte E. 1927. Bậc Eifel và Givet: Jamoida A.I. (in Dovjikov A.E. et al. 1965, 1972). - Bậc Eifeli: Dương Xuân Hảo et al, 1975,1977. Ẻtage Givetien: Tống Duy Thanh 1967. Điệp Lỗ Son: Phạm Văn Quang 1969, 1971 (D₂gv-D₃fr?); Tổng Duy Thanh 1979; Tống Duy Thanh et al, 1986 (D₂gv); Vũ Khúc, Bùi Phú Mỹ eí a l 1990 (D₂). Lo Son Fm: Tong-Dzuy Thanh et al 1988 (D₂gv). Hệ tầng Tràng Kênh: Tống Duy Thanh, Nguyễn Đức Khoa (in Vũ Khúc et al. 2000) (D₂gv); Nguyễn Hữu Hùng et al. 2004; Nguyễn Iíữu Hùng (in Tống Duy Thanh et al. 2005) (D₂gv-Djfm); Nguyễn Hữu Hùng, Tạ Hòa Phương, Nguyền Thị Thủy 2007 (Đ2gv-D₃fm); Tống Duy Thanh, Tạ Hòa Phương 2009 (D₂gv-D₃fm). Trang Kenh Fm: Tong-Dzuy Thanh et al. 1995 (D₂gv-Djfr)

Lithology and Thickness

Limestone with some interbeds of cherty shale. Lo Son area has about 400 m of: (1) Grey, dark-grey, thin- to medium-bedded fine-grained limestone containing stromatoporoids; 120 m. (2) Grey, thin-bedded cherty shale and black shale containing coniconchs; 50 m. (3) Dark-grey clayey limestone interbedded with gray shale, containing Frasnian stromatoporoids and forams; ca. 200 m. (4) Light-colored, thin- to medium-bedded limestone containing conodonts; 30 m.

Lithology Pattern:

Clayey limestone

Relationships and Distribution

Lower contact

Conformable on the Van Huong Fm

Upper contact

Conformable below the Con Voi Fm (Kinh Mon Thuy Nguyen and An Lao areas) or the coeval Pho Han Fm (Cat Ba Island, Hai Phone City)

Regional extent

Kinh Mon (Hai Duong Province), Thuy Nguyen (Hai Phong City) areas, and on some coastal islands in the Ha Long and Bai Tu Long bays, such as Cat Ba and Cho Islands.

GeoJSON

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Fossils

Caliapora battersbyi Assemblage - Late Givetian; Stachyodes costulata Assemblage - Early Frasnian; Amphipora simplex Assemblage - Late Frasnian; Palmatolepis triangularis Zone - Early Famennian

[Figure: Tràng Kênh Fm: Tabulate corals Caliapora battersbyi (D2gv); Conodonts (images courtesy of Prof. Ta Hoa Phuong, Vietnam Natl. Univ. Hanoi)]

Age

Late Givetian - Famennian. [Famennian-Tournaisian boundary is in basal beds of the overlying formations.]

Age Span:

Beginning stage:

Givetian

Fraction up in beginning stage:

0.8

Beginning date (Ma):

380.18

Ending stage:

Famennian

Fraction up in the ending stage:

0.9

Ending date (Ma):

360.48

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).