Upper Permian (Late Changhsingian) marine strata in Nan Province, northern Thailand

► In Nan area, Lower and Middle Permian limestones are rich in marine fossils. ► At Pha Dang Khwai, limestone extends up to Late Permian. ► East of Nan at Luang Prabang in Laos, the Upper Permian is rich in continental fossils. ► In Loei area in North-East Thailand, marine Upper Permian is also unknown.