Cu Bai Fm

Lower formation of the My Duc Gr. The left side of Highway No.9 leading to Khe Sanh, 2 km southwest of Dau Mau Bridge (E = 16°47'; E = 106°52') is proposed as the neostratotype, because the original stratotype from Cu Bai to A Choc villages (Huong Hoa District, Quang Tri Province) was apparently a 10 km interval of limestone scattered between beds of different units (Dai Giang Fm, A Choc Fm, Phong Son Fm).

Synonym: Calcaires de Tân Lâm: Trần Thị Chí Thuần, Fontaine H. 1968 (Famen). Hệ tầng Tân Lãm: Tống Duy Thanh, Nguyễn Đức Khoa (in Vũ Khúc et «/.2000) <D₂gv - Djfr). Các bậc Civet - Frasni (part.) Marcichev A.M., Trần Đức Lương (Dovjikov A.E. et al. 1965). Đá vôi Carbon hạ (part.): Mareichev A.M. và Trần Đức Lương (Dovjikov A.E. et al. 1965) Etage Frasnian (part.): Tong-Dzuy Thanh 1967. Các trầm tích Giveti: Dương Xuân Hào (Trần Văn Trị et al 1977). Hệ Carbon, thống hạ (part.): Lê Húng (Trần Văn Trị et al. 1977). Hệ tầng Cù Bai: Nguyễn Xuân Dương e/ ai. 1978; Dặng Trần Huyên, Nguyễn Đình Hống 1981; Nguyễn Đức Khoa 1984; Nguyễn Văn Hoành, Phạm Huy Thông 1984; Tống Duy Thanh et al. 1986, 1988; Vũ Khúc, Bùi Phú Mỹ 1^89; Nguyền Dức Khoa 1996 (D₂gv - Djfr). Điệp La Khê (part.): Nguyẽn Xuân Dương et al. 1978 (C₁). Hệ tảng Phong Nha: Lê Hùng 1981,1984; Phạm Huy Thông et al. 2000, 2001 (D₁- C₁). ỉlệ tầng Xê Băng Hiêng'. Nguycn Hữu Hùng el al. 1985 (C₁fm). Tập YunnaneHina: Tong-Dzuy Thanh et al. 1986 1988 (D₃fm). Cù Bai Fm: Tong-Dzuy Thanh 1993 (Dịgv - D₃fr); Đoàn Nhật Trường 1998 (D₂gv - C₁). Limestone Beds containing Famennian fauna - Yunnanellina: Tong-Dzuy Thanh 1993. Ilệ tầng ;Wjp tìức: Nguyễn Hữu Hùng, Doàn Nhật Trướng, Nguyễn Đức Khoa 1995 (D₂gv - C₁). Tasang Limestone: Nguyen Due Khoa 1996 (Givclian - Frasnian). Sebangkieng Fm'. Nguyen Due Khoa 1996 (Famcnnian - Toumaisian). Achoc limestone-. Nguyen Due Khoa 1996 (Famcnnian - Toumaisian). Midiic Limestone-. Nguyen Due Khoa 1996 (Famcnnian - Toumaisian).

Limestone. Stratotype: (1). Light-grey, weakly recrystallized limestone, 20 m thick; containing in abundance the stromatoporoids Tienodictyon cf. ischusaovense, Amphipora ramosa minor, and tetracorals Argutastrea lavali, Disphyllum sp. (2). Black-grey, thin-banded limestone, 5 m thick. (3). Light-grey dolomitic limestone, 20 m thick. (4). Black-grey limestone containing the stromatoporoid Amphiporapinguis, 15 m thick. (5). Light-grey dolomitic limestone containing poorly preserved brachiopods, 15 m thick. (6). Black-grey limestone intcrbcdded with pinkish clayey shale containing poorly preserved Cyrtospiriferidae brachiopods, 5 m thick. (7). Light-grey, medium-bedded dolomitic limestone, 15 m thick. (8). Black-grey, medium-bedded limestone, 5 m thick; containing in abundance the brachiopods Tenticospirifrer minor, Cyrtospirifer postarchiaci, Cyrtiopsis graciosa, C. zuongi, Uchtospirifer nalivkini, Yunnanellina triplicata, Ladogioides sp., Lazutkinia sp, Productidae, and Cyrtospiriferidae. (9). Light-grey, medium-bedded dolomitic limestone, 50 m thick. The total thickness is 150 m.

Brachiopods Cyrtospirifer sp., Uchtospirifer nalivkini, Mucrospirifer novosibiricus vietnamicus; stromatoporoids Tienodictyon tschussovense, Stachyodes costulata, Idiostroma cf. crassum, Amphipora laxeperforata, A. pervesiculata, A. patokensis, A. patokensis minor, Atelodictyon trauscholdi; tabulates Alveolitella densata, Gracilopora polonica; tetracorals Alaiophyllum incomptum, Grypophyllum cf. mackenziense; and the foraminifera Tikhinella sp., Paratikhinella sp., Tournayella jubra, Eonodosaria sp..