Phu Quoc Fm

Gulf of Thailand (Phu Quoc island). The type section is located on Phu Quoc Island, from Ghenh Dau to Rach Vcm (N = 10°20’; E = 104°). Trinh Danh et al. 1997.

Synonym: - Hệ tầng Phú Quốc: Trần Đức Lương, Nguyễn Xuân Bao et al. 1988 (J₃-K₁), Vũ Khúc, Bùi Phú Mỹ et al. 1990 (J); Trịnh Danh (in Phan Cự Tiến et al.) 1989 (J₃-K₁); (Vũ Khúc et al. 2000 (Miocen giữa - muộn); Nguyễn Ngọc Hoa et al. 1991 (K₂); Trịnh Dánli et al. 1997 (Mioccn giữa - muộn); Bùi Phú Mỹ, Trần Hồng Lĩnh 2003 (K). - Grès supérìeur: SaurinE. 1935 (J-K). - Hệ tầng Thồ Chu: Bùi Phú Mỹ, Trần Hồng Lĩnh 2002 (K₂).

Continental beds containing jet and silicified wood. The characteristic section of the Fm situated on the Ph. Quốc Island, extending from Ghềnh Dầu to Rạch Vẹm, with a thickness of about 240 m, includes: 1/ Thick-bedded polymictic conglomerate, 10 m thick; 2/ Intercalation of greyish and violetish-grey sandstone, siltstone, sandy siltstone containing thin veins of black brown coal, 90 m thick.; 3/ Light-coloured, thick-bedded, in some places, cross-bedded, coarse sandstone, conglomerate, gritstone and pebble-bearing gritstone, 240 m thick. In the Thổ Chu Island, the Fm is observed mainly within boreholes, composed of an intercalation of brown-grey sandstone and red-brown siltstone.

Characteristic section's Unit 2 contains the spores and pollens Lygodium microphyilum, Magnastriatites sp., Stenochlaena palustris, Florschuetzia trilobata, FI. levipoli, Echiperisporites sp., Dacrydium sp., Rhizophora sp; and Unit 3 contains spores and pollens Classopollis sp., Cicatricosisporites laesuratus, Cic. minutaestriatus, Cic. dorogensis with the absence of young species of Florschuetzia. In the jet-exploiting carrier, leaf imprints of Laurus similis, Phragmites oeningensis, Sabal sp. were collected. In the upper part of the Fm, there still are the silicified wood Protopodocarpoxylon orientale, Protophyllocladoxylon xenoxyloides of Early Cretaceous age. On Thổ Chu Island are the same spores and pollens with index forms as met in the Ph. Quốc Island. There, the silicified wood Protopodocarpoxylon orientale, p. paraorientale, Prototaxoxylon asiaticum near to those collected in the Ph. Quốc Island, were found

It is interpreted as Vu Nhu Hung (oral communication) carried out petrochemical study on andesite from the lower part of the Nha Trang Fm and found that it has the same characteristics as andesite of the Deo Bao Loc Fm. Therefore, this geologist considers that the Nha Trang Fm includes only acidic and subalkaline rocks of the upper part of the above described sections with a total thickness of about 350-500 m (Vu Khuc’s remark).