Document Type : Original Research Paper


1 Department of Geology, Science and Research Branch, Islamic Azad University, Tehran, Iran

2 Department of Geology, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran

3 Department of Geology, Faculty of Science, University of Isfahan, Isfahan, Iran


Devonian-Carboniferous boundary is not clear in the Eastern Alborz Mountains. In the current study Tuyeh-Darvar section with about 170 m, thickness is selected. In this investigation, the primary goal is revision of Devonian/Carboniferous Boundary (known as DCB) and the other goal is the redefinition of the DCB as a famous necessity (based on ICS program in 2008 for defining the boundary and to find a new GSSP). According to Conodont data from acid-leaching 53 carbonate samples(by acid acetic) that obtained from Late Devonian and Early Carboniferous deposits in this section, and based on standard conodont Zonation 6 Zone are recognized;1. Bi.ultimus/or Si.praesulcata Zone, 2. Pr.kockeli /or Si.sulcata Zone, 3. Si.duplicata to Si.sandbergi bio interval, 4. Si.crenulata Zone, 5.Gnathodus-P.inornatus Zone, and 6.Ps.multistriatus Zone. Considering to the Conodont Zones above mentioned, Conodont faunas and other evidences, in the Tuyeh-Darvare section the DCB, is located within cream to grey silt stone beds, which are lies between K6 limestone and K8 dark carbonate beds (about 7.10 m above the base of recent studied section).