Song Boi Fm
Type Locality and Naming
Southeast end of the Song Da – Tu Le Basin. The type section is located at Cot Bai area, situated in the basin of the Song Boi River, Kim Boi District, east of Hoa Binh Town (N= 20°39'; E= 105°35'),It was named by Nguyen Van Hoanh (in Vu Khuc, Bui Phu My et al. 1990)
Synonym: Hệ tầng Sông Bôi: Jamoida A.I. & Phạm Văn Quang (ìn Dovjikov A.E. et al.) 1965 (Carni); Vũ Khúc 1965 ('Carni), (in Trần Văn Trị et al.) 1977, 2000, (in Vũ Khúc et al.) 2000 (Ladin-Carni). - Điệp Sông Bôi: Vũ Khúc 1990. - Bậc Carni (part.): Phan Cự Tiến et al..) 1977. - Điệp Mường Trai (part.): Nguyễn Văn Hoành (í« Vũ Khúc, Bùi Phú Mỹ et al. 1990). - Điệp Nậm Mu (part.): Bùi Phú Mỹ (in Vũ Khúc, Bùi Phú Mỹ et al.1990)
Lithology and Thickness
Sandstone, siltstone: Basal conglomerate; followed by greenish to dark grey fine-grained sandstone, pinkish to dark grey siltstone with interbeds of pinkish to black, then a major unit (half of type section) of thin-bedded clayey shale, then yellowish, medium-grained quartz sandstone, brownish-grey tuffaceous sandstone and black carbonaccous shale. Total thickness of 800-850 m at the type section.
Relationships and Distribution
Lower contact
Unconformably overlying the Anisian-aged Dong Gial Fm (Boi River area) or upon the Lower-to-Middle Triassic Nghia Lo Fm (Khanh Yen area).
Upper contact
Unconformable below the Suoi Bang Fm of middle Nortian-Rhaetian in type area. However, in northwest extent, the regionally next younger (or partly coeval units) are the Ban Diet Fm and/or Lai Chau Fm (both in Lai Chau Province).
Regional extent
Hoa Binh Province - It in the valley of the Song Boi River, near Kim Boi Townlet, south of Highway Ns 6, and near the Chi Ne and Suoi Rut areas. Also KhanhYen area (Lao Cai Province).
GeoJSON
Fossils
Halobia austriaca, H. cordillerana vietnamica, H. comata, Discotropites sp>, and Sagenites sp., etc.
Age
Depositional setting
Marginal marine with coally shale.
Additional Information