Cretaceous nannostratigraphy of the Kopet Dagh Mountain Range (northeast Iran)

摘要

The Kopet-Dagh Mountain Range,which stretches nearly 650 km in a WNW-ESE direction east of the Caspian Sea from the former Soviet Union through Iran and into Afghanistan, is composed of a succession of gently folded rock. The base of this succession is only exposed in the eastern part of this mountain range in Iranian territory. The most complete Cretaceous sedimentary succession in eastern Iran is found in the Kopet Dagh Mountain Range and is comprised of marine shales, marls, and limestones and a subordinate amount of sandstone. This sequence appears to represent all major stages of the Cretaceous (Stocklin, 1968). These deposits are exposed throughout most of the Kopet Dagh Range with few exceptions. For the first time, calcareous nannofossils were used to determine the age of these sedimentary beds. The distribution and relative abundances of Cretaceous calcareous nannofossil taxa were recorded from the lower and upper boundaries of all formations (e.g., Mozduran,Shurijeh, Sarcheshmeh, Sanganeh, Aitamir, Abderaz,Abtalkh, Nizar, and Kalat) in both the eastern and western part of the Kopet Dagh.