Khe Bo Fm

Ha Tinh-Nghe An province region. The type section is located in the Khe Bo coal mine, Tuong Duong District, Nghe An Province (N = 19°16’; E = 104°29’). It was named by Nguyen Van Hoanh.

Synonym: Hệ tầng Khe Bổ: Nguyễn Văn Hóành và nnk. 1978, 1996; Trần Đức Lương, Nguyễn Xuân Bao và nnk. 1988; Trinh Dánh (in Phan Cự Tiến và nnk.) 1989; (in Vũ Khuc, Bùi Phú Mỹ và nnk.) 1990; (in Vũ Khúc và nnk.)2000; Lê Duy Bách và nnk. 199Ố; Lê Duy Bách, Đặng Trần Quân và nnk. 1996. Điệp Khe Bổ: Trịnh Dánh 1979, 1985. Neogen: Dovjikov A.E. và nnk. 1965; Lê Duy Bách và nnk. 1969; Mỉocen: Trần Đình Nhân (in Trần Vùn Trị và nnk.) 1977.

Lacustrine brown-coal-bearing beds. (1). Massive basal breccia-conglomerate, conglomerate, gravelstone grading upward into an alternation of thick-bedded gritstone, coarse-grained sandstone; 40-50 m thick. The conglomerate is brown-grey colored, having a grain size of 5-20 cm, with a composition of quartz, quartzite, sandstone, sericite schist, chert, poorly sorted and rounded; its cement is coarse-grained sandstone. (2). Brown-grey, coarse-grained sandstone grading upward into grey siltstone with some interbeđs of brown-grey sandstone, claystone, in some places, clayey shale containing pyrite crystals; 80-100 m thick. (3). Dark-grey, irregular-bedded siltstone with some interbeds of sandstone and claystone containing some black coal seams (from 0.4 to 13 m in thickness), 45 m thick. The Coal is of commercial significance and can be used in coking. (4). Intercalation of dark- to brown-grey, coarse- to medium-grained sandstone and brown-grey, irregular-bedded siltstone and some yellowish-grey, small-grained gritstone; 15-35 m thick. (5). Mainly conglomerate and gritstone interbedded with coarse-grained sandstone; conglomerate is brown-grey colored, with the pebbles, beside the composition met with in member 1, of limestone, rhyolite, violet-brown schist, poorly sorted and rounded; cement is coarsc-gfained sandstone; 250 m thick. The total thickness of the formation in this section is 500-550 m.

Laurus similis, Pecopteris totangensis, Phoebe lanceolata, Quercus lobbii, Taxus cf. baccata, Ficus beauveriei, Sapindus linearyfolius, Salix elongata, Daphne sp., Cinnamomum sp..

No fossils other than the above-cited flora have been collected.

It is interpreted as a