Permian fusulinoidean limestones from east of changwat Nakhon Sawan

The aims of this study are to identify fusulinoideas, study biostratigraphy and determine age of carbonate rocks in the areas of Amphoe Ta Khli, Amphoe Tak Fa and Amphoe Phrayuha Khin, Changwat Nakhon Sawan. The carbonate rocks in the study area are lithostratigraphically classified into the Tak Fa formation. They contain abundant fusulinoidea, algae, smaller forams, shell fragements, crinoid stems, ostracods, gastropods, bivalves, brachiopods, rare corals and locally pellets. Textures of carbonate rocks are composed of bioclastic wackestone to packstone. The fusulinoideas found in the investigated areas belong to 25 genera, 37 species: Ozawainella sp., Staffella sp., Nankinella sp., Sphaerulina sp., Schubertella sp., Eoschubertella sp., Neofusulinella spl, Yangcheinia sp., Parafusulina sp., Pseudofusulina sp., Skinnerella sp., Previtroschwagerina sp., Chusenella sp., Verbeekina verbeeki, Verbeekina (Armenia) saraburiensis, Armenia sp., Misellina sp., Misellina (Brevaxina) sp., Misellina ovalis, Misellina otai, Misellina cf. termieri, Misellina confragaspira, Misellina claudiae, Maklaya sp., Maklaya sethaputi, Maklaya pamirica, Maklaya saraburiensis, Schwagerina sp., Lepidolina lepida, Neoschwagerina sp., Neoschwagerina simplex, Sumatrina sp., Afghanella sp., Pseufodoliolina sp., Neothailandina pitakpaivani, Neothailandina sp., Thailandina buravasi and Thailandina sp., The age of carbonate rocks yielding fusulinoideas is Yakhtashian or Artinskian (late Early Permian) to Midian or Capitanian (late Middle Permian). Based on the evidences of composition and texture of carbonate rocks, they show that the depositional environment was within carbonate platform. Fusulinoidean assemblages and age in study areas are similar to the ones of the Saraburi and Lop Buri areas. It can be assumed that carbonate platform in study area have originated in the same time as the carbonate platforms in the Saraburi and Lop Buri areas. การทำวิจัยในครั้งนี้มีจุ