Tay Hon Nghe Fm

Kien Giang Province, situated on the Gulf of Thailand. Holostratotype - the unique section of the formation lying on the western side of Minh Hoa Island (also called Hon Nghe), Kien Giang Province, situated on the Gulf of Thailand (N = 10°02'; E = 104°34'). The formation is named in accord with the position of its section on the island. The Tay Hon Nghe Fm comprises terrigenous sediments overlying limestone of the Minh Hoa Fm. It is named Tay Hon Nghe to avoid repetition of the former Hon Nghe Fm name that would cause misunderstanding.

Synonym: - Hệ ®™ầng Tây Hòn Nghệ: Vũ Kh.c (in Vũ Kh.c et al. 2000 - Ladin). - Série schistogréseuse: Fontaine H., 1964 (Permi v. ỸTrias). - Hệ tầng Hòn Nghệ (part.): B.i Ph. Mỹ, Vũ Kh.c 1980 (Ladin); Vũ Kh.c, B.i Ph. Mỹ et al. 1990 (Ladin), - Hệ tầng Hòn Nghệ-. Nguyễn Xu.n. Bao et al. 1991, 2000 (Ladin); Vũ Kh.c (in Tổng Duy Thanh et al. 1995 -Ladin); Nguyễn Ngọc Hoa et al. 1996 (Ladin).

Siltstone and Claystone: The stratotype of the formation includes 4 members as follows. (1). Grey, dark grey clayey shale interbedded with thin- to medium-bedded siltstone (10-40 cm), 20 m thick. Containing the Ladinian bivalves Daonella cf. moussoni and Posidonia wengensis and some poorly preserved crinoids. (2). Intercalated dark grey siltstone and clayey shale with some interbeds of sandstone, 55 m thick. They are strongly crumpled and banded. (3). Grey, fine- to medium-grained, medium- to thick-bedded (30-60 cm) sandstone with some interbeds of siltstone and clayey shale, 75-80 m thick. (4). Greenish-grey, light violet, brown-violet in the upper part, thin-banded (0.5 cm) clayey shale with some thin interbeds (30-40 cm) of siltstone, about 50 m thick.

The total thickness of the formation in this section is about 220 m.

Ladinian bivalves Daonella cf. moussoni and Posidonia wengensis and some poorly preserved crinoids.