Diem He Fm
Type Locality and Naming
The type section is located in the Diem He area, along Highway IB from the foot of the Lung Pa Pass towards Po Cang Village, Van Quan District, Lang Son Province (N = 21° 53'; E = 106° 35'). It was established by Dang Tran Huyen (2002).
Synonym: Previously considered as lenses in the basal part of the Na Khuat Fm. Hệ tầng Diềm He: Đặng Trần Huyên 2002. Hệ tầng Nà Khuất (part.): Jamoida A.I., Phạm Văn Quang (in Dovjikov A.E. et al. 1965); Đoàn Kỳ Thụy1976; Vũ Khúc, Trịnh Thọ (in Trần Văn Trị et al. 1977); Vũ Khúc (in Vũ Khúc, Bùi Phú Mỹ et al. 1990);Nguyễn Kinh Quốc et al 1992; Đặng Trần Huyên (in Tống Duy Thanh et al. 1995).
Lithology and Thickness
Limestone: Black-grey to black, thin- to medium-bedded limestone; the surface of the beds has stylolite structures. Thickness reaches 150-160 m; however, near Lang Son City, it is only 15-30 m, and disappears toward the southern margin of the Au Chao Basin.
Relationships and Distribution
Lower contact
Conformably rests upon the underlying volcanic-rich Khon Lang Fm.
Upper contact
Conformably beneath the overlying Na Khuat Fm.
Regional extent
It occurs in the Tu Don, Diem He, Lung Pa, and Sam areas of Lang Son Province
GeoJSON
Fossils
Forams Meandrospira, Diplotremina, Frondicularia, Endotella, Ammodiscus, Glomospira and Pilammina densa (index species for Anisian). Trochammina jaunensis, Diplotr ina ex gr. astrofimbriata, Glomospirella semiplana, and Endothyraneỉla sp. Late Anisian ammonoid Kellneriites samneuaensis has been collected near Lang Son City.
Age
Depositional setting
Additional Information