Based on this study , eleven stratigraphy sections from
lower cretaceous sediments in East-North of Iran selected in
Kopeh dagh basin.These sections are located in Lat.36 45 — 35
45N and Long.61 15 - 59 45E in trend in folding of area.The 350 samples in systematics form picked from old layers to new layers.
The aim of this study is vetigation of biofacies and lithofacies of Tirgan Fm. and determine of lower and upper boundries in these sections.
These sections from west to east are:Chenar,Taherabad, Artenj, ,Ghorghoreh Mozduran, Padeha,Baghak, Shurijeh olya and
two additional sections,Natu and Derazab.
Based on lithofacies,about 13 microfacies in this area have been recognized, and based on all of the founa and microfacies, Aptian
ages were proposed for this formation in these sections.