Scientific Quarterly Journal of Geosciences

Scientific Quarterly Journal of Geosciences

Lithostratigraphy and Biostratigraphy of the Dalichai Formation West of Shahroud (Eastern Alborz)

Document Type : Original Research Paper

Authors
Maryam Shafeizad 1
Kazem Seyed-Emami 2
1 Geology Department , N.I.O.C. Exploration, 8th Central Bld., Tehran, Iran
2 Mining Department, Faculty of Engineering, University of Tehran, Tehran, Iran
Abstract
 
Middle Jurassic strata are well developed at west of shahroud (SE Alborz). In the investigated area two sections at kuh-e Parikhan and kuh-e Tepal have been studied in detail . The Dalichai Formation has a maximum thickness of 235 m consisting of an alternation of bluish-grey limestones and marls, being subdivided into 8 members. The lower boundary with the siliciclastics of the underlying shemshak Formation is sharp and discontinuous, whereas the upper boundary to the light and cliff-forming carbonates of the Lar Formation is rather inconspicuous and transitional. The Dalichai Formation in both sections is fossiliferous. Summing up 1985 fossil specimens were collected, among which the ammonites with 1749 specimens clearly predominate. The fossil-content is mainly concentrated within few meters of red and nodular limestone in the upper part of the section. Based on the ammonite fauna the age of the Dalichai Formation in the investigated area ranges from Upper Bajocian to lower Oxfordian. Pleobigeographically the fauna shows close relationship to western Europe and sub-mediterranean region. This indicates a paleogeographic position of the area at the northern Tethys during the Middle Jurassic. The depositional environment ranges from deeper shelve to deeper open marine.
Keywords
Lithostratigraphy
Biostratigraphy
Eastern Alborz
Dalichai Formation
Jurassic
Ammonite

Subjects

Alavi-Naini, M., 1972 – Etude geologique de la region de Djam – Geol . Surv.Rep.No.293 P.
Davies , R.G., Jones, C.R, Hampzepour, B. & Clark, G.C.,1972 – Geology of Masuleh Sheet 1:100000 , Northwest Iran , Geol. Surv. Iran Rep . 24:1-110,13 figs. , 1 map, Tehran .
Jenkeyns, H.C.,1974 –  Origin of red  nodular  limestones (Ammonitico Rosso, Knollenkalk) in  the  Mediterranean  Jurassic : a diagenetic model. In : Pelagic sediments : on Land an under the Sea (Ed. By K.J.Hsu and H.C.Jenkyns). Spec. Publs int . Ass Sediment .1,249-271.
Jenny,J.,1977 – Geologie et stratigraphie del Elburz Oreintal enter Aliabad et shahrud, Iran – De la Terre Theses Fac. Sci.Univ. Genev;1-238:175-189.
Nini,C., Nocchi, M. & Venturi, F., 1997 – The Toarcian marly – calcareous successions in the M.Martani area (Northern APPenines ) : lithostraphy, biostratigraphy , Paleoecology and effects of Tethysian events of the depositional environment. Boll.Soc . Paleant . Ital .35: 281 – 319 , 12 figs ., 6 pls. Modena (for 1996).
Seyed – Emami ,K. , Schairer, G. , Alavi-Naini,M.,1989 – Ammoniten aus der unteren Dalichai Formation (unterbathon) Ostlich Von Semnan (SE – Alborz, Iran).Munchner Gerwiss . Abh., (A), 15,79-91,4Abb.,1Tab., 3 Taf.
Seyed – Emami, K. ,Alavi-Naini, M.,1990 – Bajocian Stage in Iran. – Memoire descrittive della carta geological dlalia , volume XL:215-222,3figs. , 2 Tap .
Seyed-Emami, K. , Schairer, G., Aghanabati, A. , Fazel, M. ,1991 -Ammoniten aus dem Bathon der Gegend Von Tabas-Nayband (Zentraliran) , Munchner Geowiss. Abb. (A) 19, S: 65-100 , Mit 3 Abb , 2 Tab. , 8 Taf .
Seyed-Emami, K. , Schairer, G., AghanabatiI, A., Fursich, F. T. , Senoebari-Daryan, B. , Majidifard, M.R.,1998-Cadomites aus der unteren Baghamshah Formation (Ober bathon , Mittlerer Jura) SW Tabas (Zentraliran)-Mitt.Bayer. Staatsslg. Palaont . hist . Geol.38 , 111-119, 2 Abb. , 1 Taf . 
Seyed-Emami, K. , Fursich, F. T. , Schairer , G.,2001- Lithostratigraphy , ammonite faunas and Paleoenvironments of Middle Jurassic Strata in North and Central Iran.Newsl. Stratigr . , 38(2/3) , 163-184, 11 Fig .
Stampfli, G. M.,1978 – Etuda geologique generale de L' Elburz oriental au S.De Gonbad-e-Qabus , (Iran.NE). – De la Terre These Fac . Sci. Univ . Genev, 1-328:154-160 .
Steiger ,R.,1966 – Geologie der west – Firuzkuh Area(zentral Elburz , Iran). – mitt.Geol.Iran.E.T.H univ . Zurich , N.S ; 1-145.
Tucker,M.E.,1974 – Sedimentology of Paleozoic pelagic limestones: the Deronian Griotte (southern France) and Cephalopoden Kalk (Germany). In : Pelagic Sediments : on Land and under the Sea (Ed. By K. J. Hsu and H. C. Jenkyns).Spec.Pulbs int . Ass. Sediment . 1,71-92.
Scientific Quarterly Journal of Geosciences
Volume 14, Issue 55
Spring 2005, Vol.14, No. 55
Spring 2005
Pages 98-113