Cha Pa Fm
Type Locality and Naming
Lower formation of the Sa Pa Gr. The type section is located along the dirt road from Ta Phinh Village to Milestone N°32 Bridge (situated on the Sa Pa - Lao Cai Road) through Cha Pa Village towards the mount of dolomitic marble (N = 22° 22'; E = 103° 52'). It was named by Nguyen Van Hoanh.
Synonym: Hệ tầng Cha Pá: Nguyễn Vàn Hoành et al. 2000. Série de Sa Pa: Jacob c. 1921 (Algonkien). Série dẹ CocXan (part.): Fromaget J, 1937. (Algonkien supérieur). Hệ tầng Sa Pa (Upper Proterozoic): Bùi Phú Mỹ et al. 1971. Trần Văn Trị el al. 1977. Hệ tầng Chiêm Hoá (part.): Dovjikov A.E. et al. 1965 (Proterozoic)
Lithology and Thickness
Cha Pa Village section is 500 m thick of metamorphosed terrigenous sediments: (1). Quartz-feldspar-muscovite schist interbedded with muscovite schist, quartz-muscovite-sericite schist and grey quartzite; over 300 m thick. (2). Muscovite schist interbedded with tremolite schist, talc-tremolite schist, calcite-muscovite schist and thin-bedded dolomitic marble; about 200 m thick.
Relationships and Distribution
Lower contact
Has tectonic contact with older units.
Upper contact
Conformably below the Da Dinh Fm
Regional extent
Outcrops in small areas scattered from Lao Cai through Yen Bai provinces to north Hoa Binh Province.
GeoJSON
Fossils
No fossils have been collected.
Age
Depositional setting
The Cha Pa Fm was formed in a shallow-marine environment (according to the entry in Tong-Dzuy Thanh and Vu Khuc (2011; Stratigraphic Units of Viet Nam, 2011).
Additional Information