Writers : Mansoori daneshvar, Parviz; supervisor:R. Moussavi Harami, A. Mahboobi; advisor:M. Nagafi
Refference : M.Sc.Thesis _ Ferdowsi university, Mashhad
Publishing Year : 1382

Abstract :

The Kopet-Dagh sedimentary basin, formed after Early Kimmerian Orogeny.
Middle Triassic age. Southern part of this basin located in north east Iran.
The Upper Maastrichtian Kalat Formation was deposited on a carbonat platform developed across the elongate Kopet - Dagh basin. Three stratigraphic sections of this Formation were measured at the entrance of Kalat Syncline section 1), Khesht Village (section2 )and Tang-e-Chahchahe (section3). The( thicknesses of Kalat Formation in this sections are 166.5, 120 arid 146.5 meters respectively. This Formation conformably overlained the Neyzar Formation and .underlained the Pesteligh Formation.
The Kalat formation divided into three units ) sandy limestone, fossillifcrou5 limestone and alternation of fossilliferous limestone with shale) in section 1, lwc units (sandy limestone and alternation of fossillifcrous limestone with shale) in section 2 and six units (lower limestone, lower rudistid limestone, shaIe, upper :limestone, upper rudistid limestone and alternation of limestone with shale)in 3 section.
Based on Petrographical studies on 120 thin sections, five facies associations including facies associationA (very fine sandy pelmicrite, sparse biomicrite,silty benthic foraminifera biomicrite ) facies association B ( unsorted silty oyster bioniicrudite, very fine sandy oyster biopelmicrudite), facies association
poorly washed intraclast inilliolid biosparite, poorly washed biospanite,unsorted sandy biosparite and bryozoan oyster biomicrudite, facics association D( bioclastic oospanite, rounded redalgal rotalia biospanite, crinoid bryozoan (biosparudite) and facies association E(unsorted sandy redalgal nudist biosparudite, sandy redalgal biosparite, rudistid biolithite, coral biolithite and redalgal bjolithite ) were identified. These facies associations were deposited in restricted lagoons, lagoonal bars, semi - restricted lagoons, barrier bars and open . marine environments, respectively, on a carbonate ramp pIatform
، Petrographical studies revealed that diagenetic processes such as micritization , cementation, boing, burrowing, neomorphism, compaction, glauconitization heniatitization, dolomitization, silicification, dissolution and gypsification affected carbonate scdinients of Klat Formation. These processes Were operated in marine ,and meteoric diagenetic environments in eogenctic stage near surface), burial diagenetic environment in mesogenetic stage (burial)and(burial to meteoric) diagenetic environments in telogenctic stage (uplift Based on sequence stratigrphic studies, three depositional sequences wen identified in Tang- e - Chahchahe section while other sections deposited during two depositional sequences. In all sections, lower and upper contacts of the Kalat formation is a Type 1 sequence boundary but other sequence boundaries are
2 from Type Transgression of sea level caused to developing transgressive systems tracts that consists of a retrogradational stacked shallowin-upward paras sequences or trainsgressive cycles. Also,highstand systems tracts that consists of parasequetices ، aggradational and progradational stacked shallowing - upward resulted from regression of sea level.
Paleog eograpic reconstruction of studied region showed that Kalat Formation deposited in 8 different stages during Upper Maastrichtian time. Noted that the 3 stage 6 to 8 were developed merely in section.

Subject List : Depositional environment