Paper Information

Journal:   JOURNAL OF SCIENCE (UNIVERSITY OF TEHRAN) (JSUT)   SPRING 2007 , Volume 33 , Number 1 (SECTION: GEOLOGY); Page(s) 15 To 25.
 
Paper: 

PETROGRAPHY AND GEOCHEMISTRY OF DOLOMITES IN THE LOWER CRETACEOUS DEPOSITS OF EASTERN ESFAHAN

 
 
Author(s):  ADAABI M.H., MORADPOUR M.*
 
* SHAHID BEHESHTI UNIVERSITY, SCHOOL OF EARTH SCIENCES, DEPARTMENT OF GEOLOGY, TEHRAN, IRAN
 
Abstract: 

The study area, in the eastern mountains of Esfahan city is located about 1 kilometer of Esfahan-Naeen road at the latitude of 32°, 28' N and longitude of 51°, 47' E. The thickness of the Lower Cretaceous sequences is 196.6 meters and consists mainly of siliciclastic and carbonate rocks. The lower boundary of these deposits with the Jurassic Shales is in the form of angular unconformity. Based on petrographic studies four distinctive types of dolomites in the Lower Cretaceous successions have been recognizes. These are as follows: type-I – very fine to finely crystalline (planar-subhedral) dolomite, type-II - fine to medium crystalline (idiotopic-por-phyrotopic) dolomite, type-III - medium crystalline (euhedral) dolomite and type-IV - medium to coar-sely crystalline (euhedral) dolomite. The early dia-genetic processes generated dolomites type-I and other types are related to burial diagenesis. The type-II formed by replacement, type-III formed by re-placement/recrystalization and type-IV is pore filling dolomite. Geochemical (elemental) studies such as high Sr and Na indicate that dolomitization process-ses occurred in the limestone with original aragonite mineralogy. The source of magnesium for different types of dolomite is: seawater (for type-I) and for other types could be connate water, clay minerals of the Jurassic shales locating under the Lower Creta-ceous sequences.

 
Keyword(s): PETROGRAPHY, GEOCHEMISTRY, DOLOMITIZATION, LOWER CRETACEOUS
 
References: 
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