Late Devonian–Mississippian conodont biostratigraphy of the Chelcheli section, NE Shahrud (Eastern Alborz, North Iran)

Devonian/Carboniferous conodonts from the Chelcheli section in the Alborz Mountains were investigated. Although conodonts are generally less abundant in the entire section, important zonal index taxa of the widely applied conodont standard zonation could be used for a precise conodont zonation. Forty-seven conodont species belonging to fifteen genera were identified and led to the discrimination of fifteen conodont zones, ranging from the Palmatolepis minuta minuta Zone into the Scaliognathus anchoralis-Doliognathus latus Zone. At the Devonian/Carboniferous boundary (DCB), characteristic lithologies such as black shales and massive sandstones represent equivalents of the Hangenberg Black Shale and Hangenberg Sandstone. Close to the DCB, there is a small stratigraphic hiatus in the conodont record which might be a result of facies (shallow-water succession with no conodont record and siliciclastic rocks) rather than a period of non-deposition as the sedimentological record seems continuous. Similar to other DCB sections in shallow-water facies in Iran the two biostratigraphically important species Protognathodus kockeli and Protognathodus kuehni do not occur.