Biostratigraphy of permian rocks at Khao Nong Hoi, Changkhon Ratchasima, with reference to fossil ammonoids and fusulinids rock strata

Abstract

This research aims at study morphology of ammonoids and fusulinids in order to identify and classify fossils assemblage at Khao Nong Hoi, Amphoe Pak Chong, Changwat Nakhon Ratchasima. The second purpose is to make the range chart and establish the biostratigraphic zonation of the study area. The ammonoids in the investigated area can be identified into 10 genera 17 species: Agathicerassp.; Agathiceras mediterraneumToumanskaya, 1949; Adrianites marathonensis Bose, 1917; Adrianites cancellation Smith, 1927; Prostacheoceras pamiricus (Bogoslovskaya, 1978); Stacheoceras brunsonorumMille r and Cline, 1934; Stacheoceras rothi Mille r and Furnish, 1940; Stacheoceras mediterraneumGemmellaro, 1887; Perrinites sp.; Perrinites tardus(Mille r and Furnish, 1940), Tharalson, 1984; Perrinites cf. hilli (Smith, 1903), Mille r and Furnish, 1940; Thalassoceras welleri (Bose, 1917), Mille r and Furnish, 1940; Daraelites sp.; Propinacoceras beyrichi Gemmellaro, 1888; Propinacoceras americanum Mille r and Warren, 1933; Another 2 genera, Popanoceras sp. and Parapronorites sp. could possibly be new species. The fusulinids in the investigated area belong to 7 genera: Robustoschwagerina sp.; Parafusulina sp.; Pseudofusulina sp.; Misellina sp.; Pamirina sp.; Thailandina sp.; and Quasifusulina sp. Most of fossil assemblage in the study area ranges in age from the Asselian to the Roadian. Three biostratigraphic zones can be established by using the following ammonoids and fusulinids as index fossils; Robustoschwagerina Biozone, Misellina Biozone, and Perrinites Biozone respectively in ascending order.