Facies Analysis, Depositional Environment and Diagenetic Features of the Qom Formation in the Saran Semnan, Central Iran ()
ABSTRACT
In this study, to
identify and analyze facies of depositional environment and depositional model
of Qom Formation, stratigraphic Saran Section (southwest of Semnan) was
selected. Qom Formation in Saran section includes about 380 meters of
conglomerate at the base, chalk, limestone, marl, and shale. Petrographic
studies with facies analysis have led to the identification of 12 microfacies,
these microfacies have been deposited in four facies groups including tidal
flat, lagoon, barrier and open marine. Study of horizontal and vertical facies
changes and their comparison with recent and ancient environments reveals that
Qom Formation in this section relates to shallow marine environment and its
facies were deposited in a shelf carbonate platform and are comparable with
contemporary shelf platforms such as Florida and old shelf platforms such as
Mozduran. The most important diagenetic processes affecting the studied section
include micritization, bioturbation, cementation, dissolution, neomorphism,
fracturing, mechanical and chemical compaction, hematitization and
dolomitization. These processes have formed in marine, meteoric and burial diagenetic
environments.