Sam Son Fm
Type Locality and Naming
The type section is located within borehole N2 15 drilled near the Ham Rong Bridge (Nam Ngan Ward, Thanh Hoa City, Quang Tri Province), at 73.7 - 53.0 m (N = 19°44’; E = 105°54’). It was named by Pham Van Hai.
Synonym: Thach Han Fm. Tằng Sầm Sơn: Nguyễn Đức Tâm 1976 (Độ tứ); 1980, 1981, 1982 (Neogen). Hệ tầng Sầm Sơn: Phạm Vău Hài in Trịnh Dánh (Vũ Khúc vá nnk. 2000) Pliocene – Pleistoccnc
Lithology and Thickness
Delta-plain deposits. 1. (73.7-72 m): black-grey, thin-beddcd loose sand and silt, 1.7 m thick; containing plant remains preserved in the form of phytoleim with Pterocarya sp., Carya sp., etc. (2). (72-71 m): greenish-grey, black-grey, thin-bedded silty clay, 1 m thick. (3). (71-67.8 m): coarse sand and grit, mainly of quartz, 3.2 m thick. (4). (67.8-53 m): yellowish, but greenish-grey in the upper part, weakly lateritized silty clay, 14.8 m thick. The total thickness of the formation in this section is 20.7 m.
Relationships and Distribution
Lower contact
Unconformably rests upon Devonian (?) sediments and other old formations in type area. Regionally, next older unit is the Miocene Dong Hoi Fm.
Upper contact
Quaternary
Regional extent
Than Hoa through Ngang Pass of Quang Tri Province, and Hau Loc area of Thank Hoa Province.
GeoJSON
Fossils
Containing a palynological assemblage of 33 species, among them there are Acrostichum sp., Nymphaeaceae gen. indet, together with the diatoms Aciinella sp., Flagillaria sp.. In the Ha Tinh - Ky Anh coastal plain the Sam Son Fm also includes sediments of the coastal swampy facies, from 5-6 to 50 m in thickness, containing the forarmnifera Ammonia beccari, Elphidium cf. advenum, Quinqueloculina sp..
Age
Depositional setting
It is interpreted as a deltaic plain.
Additional Information