oa Sachun type section lithostratigraphic and biostratigraphic reappraisal, Kuh-e Sachun, Fars province, Iran

The type section of the Paleocene-Early Eocene Sachun Formation (revised age and thickness 944 m, previously 1,444 m) was originally defined by James and Wynd (1965, AAPG Bulletin, v. 49, p. 2220-2221) in the paper: Stratigraphic nomenclature of Iranian oil consortium agreement area. The type section of the formation in Kuh-e-Sachun, south of Darab city, was reappraised using new field data and microscopic studies. New evidence showed that no evaporitic sediments occur in the lower third of the formation; instead this section consists of thick-bedded to massive rudistic reefal limestone with pelagic and coraliferous marls. The lower section resembles in lithology, facies and morphology the underlying Tarbur Formation. A palaeosol horizon was observed between the Tarbur and Sachun formations and it is correlated to the Cretaceous-Tertiary (KT) boundary. The new data, together with field data from the Tarbur Formation, required revising the definition of both formations. The boundary between them has been<br>repositioned between the Tarbur rudistic limestone and the first Sachun evaporites. These revisions, including the revised age and thickness, resolve the contradictions in the published definitions, and clarify the stratigraphy in boreholes and outcrops in the Fars Province.