Chang Pung Fm

Lower formation in Ham Rong Gr version of East Bac Bo. Following the track from the Chang Pimg border post (Viet Nam - Chinese border) to the Nho Que River (N = 23° 17’, E = 105°25’)- Deprat J. 1915. Deprat J. (1915) described the section following the track from the Chang Pung border post to the Nho Que River, and defined the “Série de Chang Poung” with a thickness of 805 m.

Synonym: Série đe Chang Poung'. Deprat J. 1915 (Acadien - Potsdamien); Hệ tầng Chang Pung; Hoàng Xuân Tình el al. 1976 (Điệp - Upper Cambrian); Phạm Kim Ngân 1980,1986 (Upper Cambrian); Tiần Xuyên et al 1987 (Điệp - Upper Cambrian); Phạm Kim Ngân, Lương Hồng Hược 1995; Vũ Khúc, Bùi Phú Mỹ et al. 1990 (Điệp - Upper Cambrian); Lương Hồng Hược ei «/. 1994 (Upper Cambrian); Lê Văn Giang et al. 1997 (Upper Cambrian); Nguyễn Văn Thế et al. 1999 (Upper Cambrian); Hoảng Quang Chỉ et al. 2000 (Upper Cambrian); Tống Duy Thanh in Vũ Khúc et al. 2000. • Hệ Cambrí, thống thượng: Vasilevskaia E.D. in Dovjikov A.E. el al. 1965; Phạm Kim Ngân 1970, 1975, 1976); Phệm Kim Ngân, Lương Hồng Hược 1977; Trần Văn Trị et al. 1977; Phạm Kim Ngân, Lương Hồng Hược, Phạm Đình Long 1986

Limestone: The Chang Pung Fm is composed mainly of gently dipping beds of carbonate sediments - micritic limestone, dolomitic limestone, oolitic limestone interbedded with clayey shale, siltstone and sandstone containing shallow-water marine fauna with trilobites and brachiopods. Upward succession in type section (805 m): (1) Black to grey, thin-bedded limestone and dolomitized limestone; 225 m, containing trilobites. (2) Greenish-gray shale, siltstone and calcareous siltstone containing brachiopods; 200 m. (3) Ash-grey limestone and laminated clayey limestone interbedded with greenish-gray shale and siltstone in the lower part; 220 m; containing small-sized trilobites. (4) Greenish-gray shale, siltstone with interbeds of limestone and dolomitic limestone; 160 m; with trilobites.

[Figure: Chang Pung Fm: Outcrop of Cambrian limestone of Chang Pung Fm in Lũng Cú commune, Dong Văn Distr. (images courtesy of Prof. Ta Hoa Phuong, Vietnam Natl. Univ. Hanoi)]

Trilobites and brachiopods. Lower part - Drepanura sp., Damesella brevicaudata, Parablackwelderia spectabilis, Cycỉoỉoremelia tonkinensis, Paracoosia deprati, Pseudagnostus douviỉỉei; Middle parts - Prochuangỉa mansuyi, Irvingeỉỉa sp., Pagodia hagiangensis, Caulaspina convexa, Biilingsella tonkiniana; Upper part - Haniwa sp., Prosaukia angulata, Saukỉa acamus, Caỉvỉneỉỉa walcotii.

[Figure: Chang Pung Fm: Cambrian Trilobite Fossils (3 images) (images courtesy of Prof. Ta Hoa Phuong, Vietnam Natl. Univ. Hanoi)]

[Figure: Chang Pung Fm: Cambrian Brachiopod Fossils (2 images) (images courtesy of Prof. Ta Hoa Phuong, Vietnam Natl. Univ. Hanoi)]