Biostratigraphy of Devonian-Carboniferous boundary in Tuyeh-Darvar section, north of Iran

Abstract

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.<em> Bi.ultimus/or Si.praesulcata </em>Zone<em>, </em>2<em>. Pr.kockeli /or Si.sulcata Zone, </em>3.<em> Si.duplicata to Si.sandbergi bio interval, </em>4<em>. Si.crenulata </em>Zone, 5.<em>Gnathodus-P.inornatus</em> Zone, and 6.<em>Ps.multistriatus</em> 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 K₆limestone and K₈dark carbonate beds (about 7.10 m above the base of recent studied section).