Biostratigraphic Study of Paleozoic and Mesozoic Groups in Central and Northern Thailand

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The main purposes of this project are summarized as follows;1,establishment of biostratigraphy and correlation of the uppermost Permian and lower Triassic,and 2,ezamination of the Permian palaeobiogeography in Thailand.The surveyed regions are represented by three areas,namely(1),Lampang-Phayao area,(2),Kok Sam Rang-Phetchabun area,and(3),Loei-Pak Chom area.In the Lampang-Phayao area the uppermost Permian ammonoids such as Pseudogastrioceras sp.,Paratirolites sp.nov.,and Paraceltites? sp.were investigated from a weathered mudstone.In addition to them some representative Upper Permian foraminifers were also discriminated from a limestone which overlies the ammonoid-bearing mudstone.Triassic brachiopods were also investigated from a neighbouring locality.Establishment of the stratigraphic succession including the Permo- Triassic boundary will be strongly expected in this area.In the Kok Sam Rang-Phetchabun area Middle Permian limestones and nudstones widely distribute,and the Carboniferous and silurian nudstones are also distributed in the Loei-Pak Chom area.Many kinds and abundant fossils were obtained from these areas. They are very useful for discussing the change of palaeoenvironments and palaeobiogeography during Silurian and Permian.