Abstract

Ladinian aged formations in Northwest Bắc Bộ Việt Nam are correlated and characterized by two typical geological sections. One section is characterized by terrigenous sediments interbedded with carbonates, containing bivalve fossils of Early Ladinian age (T₂l₁), overlying unconformably the Anisian-aged carbonate formation . The other section is composed mafic extrusive, terrigenous and carbonate formations bearing Late Ladinian bivalve fossils, which overlie unconformably the older rocks and gradually grade into the overlying Carnian-aged terrigenous sediments. The lithologic characteristics, stratigraphic relations and typical Ladinian fossils show that in the Northwest Bắc Bộ Việt Nam exists a stratigraphic unconformity  in the middle of Ladinian.