New insights into the conodont biostratigraphy and paleobiogeography of the Katkoyeh Formation (Lower–Upper Ordovician) at the Katkoyeh Section, East-Central Iran

Abstract

The Katkoyeh Formation comprises most of the Ordovician strata in the Kerman Province of East-Central Iran. However, determining its depositional timing remains challenging due to conflicting biostratigraphic ages, regional stratigraphic gaps, and tectonic complexities in the area. To enhance the understanding of the Katkoyeh Formation, a new conodont sampling was conducted at the Katkoyeh type section, which revealed 1,937 conodont elements belonging to 31 species of 26 genera. They allow the recognition of the Juanognathus variabilis Range Zone (middle–upper Floian) and the Icriodella superba Range Zone (Katian–?Hirnantian) in the Katkoyeh Formation, leading to better biostratigraphic and intercontinental correlations of the Ordovician strata in East-Central Iran with the Precordillera, the Famatina System, and the Central Andean Basin of northwestern Argentina, as well as with North American Midcontinent and North Atlantic basins, and South China. Moreover, the oral structure of Juanognathus variabilis Serpagli is reassessed based on the new Iranian records, recognizing 7 morphotypes in its apparatus structure, referred to the M, Pa, Pb, Sa, Sba, Sbb and Sc positions.