Middle Permian (Murgabian) Foraminifers Faunas of the Thitsipin Formation, Western Part of the Southern Shan State, Myanmar

The Thitsipin Formation exposed at the Pegin Pagoda Hill, Ywa-ngan Township, southern Shan State, Myanmar, represents an important Middle Permian (Murgabian) carbonate sequence within the Shan Plateau. This study presents detailed lithologic, stratigraphic, and paleontological analyses of the limestone unit, focusing on the taxonomy and biostratigraphic implications of its foraminiferal assemblages. Fieldwork involved measurement of stratigraphic sections, fossil sampling, and petrographic examination of 30 thin sections. The lithology is characterized by alternating dark grey, fossiliferous lime-mudstone and crinoidal grainstone interbedded with purplish calcareous shale, forming a 78-meter-thick sequence. Four foraminiferal genera Lunucammina sp., Nodosaria sp., Pachyphloia sp., and Multidiscus padangensis were identified. Among these, Pachyphloia sp. and Multidiscus padangensis are indicative of the Middle Permian (Murgabian) age. The basal portion of the Thitsipin Formation unconformably overlies the Silurian Linwe Formation and yields abundant bryozoans, crinoids, and gastropods, suggesting a shallow marine depositional environment with moderate energy conditions. The discovery of Multidiscus padangensis allows biostratigraphic correlation with coeval units such as the Htam Sang Limestone in Hopong Township. The results confirm the Middle Permian age of the Thitsipin Limestone and refine the regional stratigraphic framework of the southern Shan State. Furthermore, the study provides essential paleontological evidence for understanding the evolution of Permian carbonate platforms in Myanmar and offers a valuable reference for future regional correlations and educational purposes in stratigraphy and paleontology.