New investigations in Stratigraphy and depositional Environment of Cretaceous deposits Kuh ? e-Khurzin In North Mahallat

Category Paleontology and Stratigraphy
Group GSI.IR
Location 23th symposium on geosciences
Holding Date 05 May 2008

      There are adequate outcrops belonging to Cretaceous deposits in Kuh ? e ? Khorzin in southwest Khorhe village.Based on detail study of stratigraphy and paleontology , against some of Geologist`s opinion, We conclude that cretaceous deposits in this section are divided to lower cretaceous deposit and upper ones That they can be distiguished well by its Microfauna assemblages. Most of these deposits are related to lower cretaceous .The age of Late Cretaceous deposits is cenomanian and conformably overlies on the Early cretaceous deposit. also The lower cretaceous sediment succession is divided into basal part and upper part. The basal part of section consist clastic - carbonate deposits that overlies on dark shale and sandstone of shemshak formation with angular unconformity and it can be considered equivalent by Dareh-Zereshk and Sangestan formations (Taft-Yazd) and the age of this part is Late Neocomian - Early Barremian based on Stratigraphic position and its Microfauna Assemblage. this part is identified as Khorhe Formation (unformal ) by Authors for the first time.
   The upper part of Early cretaceous sediment succession also consists gray - bluish thin bedded to massive orbitolina limestone that partly is shaly and marly. the age is Albian - Barremian based on microfauna assemblages and conformably overlies the basal part sediments.(Khorhe formation) And underlies thick bedded to massive inoceramous -Ovalveolina limestone And it can be considered equivalent by Taft and Shah-kuh formations. for the first time this part is identified as Haftad Gholleh Formation (unformal ) by Authors.
   Based on studies done , The beginning of Transgrassion sea in the study area can be considered Late Neocomian-Early Barremian that continued until cenomanian. This Transgrassion was after tectonic occurrence of Epirogenic (Late simerian ) that leads to considrable gaps in upper jurassic and angular unconformity in basal part of lower cretaceous deposits .