La Khe Fm
Type Locality and Naming
Holostratotype - the section at La Khe Railway Station, Huong Khe District, Ha Tinh Province (E = 13°04'30", E = 105°48'30"). The formation bears the name of this station.
Synonym: Hệ tầng La Khé: Mareichev A.M., Trần Đức Lương (in Dovjikov A.E. et al. 1965); Lê Hùng 1973, 1975; Trần Tinh eí aì.1979 (part.); Phạm Huy Thông, Nguyễn Văn Hoành 1980 (part.); Đoàn Nhật Trường (in Phạm Kim Ngán et al. 1990); Đoàn Nhật Trưởng (in Tống Duy Thanh et al. 1995). Schisíes marneux de Bai Due à Philiipsia propinqua: Dcprat J. 1914. Schistes de La Khé à Phiỉlipsia gemmuli/era et Chonetes comoìdes: Fromaget J. i 927. Điệp La Khê (part.): Nguyễn Xuân Dương et al. 1977; Nguyễn Văn Hoành et al. 1978; Nguyễn Quang Trung et al, 1984; Nguyền Văn Hoành et al. 1985
Lithology and Thickness
Sandstone-claystone in lower part, carbonate in upper part. In La Khe area, it is 210-480 m of: (1). Coarse-graincd quartz sandstone interbedded with claystone, 30 m, with brachiopods; (2). Violet and black clayey shale, carbonaceous shale, 100-150 m. (3). Cherty limestone, 80-100 m.
Relationships and Distribution
Lower contact
Unconformable on the Tournaisian-age Phong Nha Fm (central North Trung Bo), or on Devonian-age Khanh Thanh Fm (Nghe An Province).
Upper contact
Conformably under the Bac Son Fm.
Regional extent
The La Khe Fm occurs largely in the Truong Son Folded Region with large differentiation of lithology. In the Song Ca Synclinorium it is exposed in the Muong Xen and Con Cuong areas.
GeoJSON
Fossils
Pseudoendoihyra powowensis and Mediocris ovalts cupellaeformis.
Age
Depositional setting
Additional Information