Abstract

The article presents some new research results on the Upper Paleozoic in North Bắc Bộ received from special studies carried out by the Việt Nam Institute of Earth Sciences and Mineral Resources in recent years. The results indicate that the lower boundary of the Bắc Sơn Formation is unconformable one, including two types corresponding to two main facial types developed in the Late Devonian - Early Carboniferous stage. The age of the Bắc Sơn Formation is Early Carboniferous Visean - Late Permian Wuchiapingian. The Đồng Đăng Formation is Late Permian Changhsingian in age with two types of sections, one of them characterizes for the An Châu structural zone and the other for the Sông Hiến one. The article touches upon also the position of the Đồng Đăng bauxite bed, the boundary between the Đồng Đăng and Triassic formations and the preliminary P/T boundary.