SUMMARY
New materials on the
Nặm Mặn Formation, Mường T� area
B�i Ph� Mỹ, Đo�n Nhật Trưởng,
Nguyễn Đ�nh Hữu,
Nguyễn Văn Ho�nh, Nguyễn Văn Lồng
������ The Nặm Mặn Formation (T3c-n nm) was established in 2001 by authors of the Geological and Mineral Map of the Mường T� map sheet group at 1:50.000 scale [3]. According to these geologists, this Formation is composed of conglomerate, gritstone, sandstone, shale, marl and limestone, 150-200 m thick. It rests unconformably upon granite of the Pu Si Lung Comphex (γC1 pl) and under the Suối B�ng Formation (T3n-r sb). Sediments of the Nặm Mặn Formation contains Carnian and Norian bivalves and Middle-Late Triassic foramiferas and hexacorals. On the other hand, the Formation was correlated to the P�c Ma Fm with the remark that the Nặm Mặn is younger.
In March-April of this year, the
authors of this article carried out the field survey of the study of Formation
stratotype. Two fossil collections were obtained. Corals have been yielding the
Late Carnian age, while bivalves � Norian. The formation is
composed of terrigenous and carbonate sediments. It is the lowest part
of the Suối B�ng Formation.
Người
bi�n tập: Vũ Kh�c