Lithological charateristics of Hn Chuối Formation

Đo Viết Cảnh, Nguyễn Văn Dũng

Hn Chuối Formation is distributed in the Hn Chuối and Hn Bung islands (about 39 km W-SW of Sng Đốc Habour, C Mau province) and divided into 4 lithological members, namely from the bottom to top: The member 1 includes very thin to thin bedded dark grey volcanic ashes, overlying is thicker bedded shale, silty shale in grey to dark grey and red brown colour; The member 2 mainly consists of thin bedded volcanic ashes in light grey colour with interbedded thin tuff sandstones and dark grey carbonates; The member 3 predominantly encompass of dark grey shale, silty shale, thin to very thick and blocky volcanic ashes with minor grey to greenish dark grey andesite tuff; The member 4 includes very thin to thin beds of grey, light grey volcanic ashes with mterbedded dark grey shale, silty shale and andesite tuff layers There are some poiphyry andesite dykes cut through Hon Chuoi Formation; in some areas, epidote veins appear as pseudo ribbon-layers. Especially, some dark grey carbonate and shale samples of Hn Chuối Formation show high Total Organic Contene (TOC = 1,65-1,98%Wt). Tectonic setting, depositional environment and geological age of the Hon Chuoi formation were also discussed. Based on radiolaria fossil, in combination with previous reported works, the deposition age of the Hn Chuối Formation is perhaps late Carbonian early Permian.

Người bin tập: PGS. TS. Bi Minh Tm