TITLE:
Microfacies, Sedimentary Environment and Sequence Stratigraphy of Gadvan and Darian Formations in the Zagros Basin, South of Semirom, Iran
AUTHORS:
Mohammad Kazem Hamedanian, Seyed Hamid Vaziri, Mahnaz Amir Shakarami, Mehran Arian, Naser Arzani
KEYWORDS:
Zagros, Gadvan, Darian, Cretaceous, Sequence Stratigraphy
JOURNAL NAME:
Open Journal of Geology,
Vol.6 No.9,
September
27,
2016
ABSTRACT: Gadvan
and Darian formations are in the upper part of Khami group that has been deposited
in the highland Zagros zone and the southern Margin of Neotethys. These formations
outcrop in the south of Semirom (Agh-Dagh Mountain) consist of Orbitolina limestones and marly limestones with a Late Barremian-Aptian age and thickness
of 520 meters. Based on field characteristics, petrographic and texture of
facies, these rocks consist of Oregonian facies (Urgonian facies) with 12
carbonate microfacies which are
deposited in Lagoon, barrier and shallow open marine. The absence of loss and
flows of turbidities indicates that carbonate platform of Gadvan and Darian formations
in the studied area are (Hmoklinal) platform type. Abundance of rudist (bivalves) and Peloid markers show that there is a Photozoan collection in tropical climates.
In the above sedimentary succession, from a sequence stratigraphic perspective,
three sedimentary cycles were recognized which deposited in a platform
model. The Gadvan Formation overlies on Fahliyan Formation disconformable and
is covered by Darian Formation gradual with reducing the amount of marl and increase of limestone. The
Kazhdumi Formation is exposed disconformably with hematite nodules and oxidized
sediments over the Darian Formation. On the basis of petrographic studies, diagenetic
process of Gadvan and Darian formations in the study area includes cementation, the physical and
chemical density and replacement processes such as pyritation, ironies and
silica. Porosity observed in the study area is mainly inter-granular porosity
type, modular and vaggy.