Microfacies analysis and paleoenviornmental interpretation of the Qom Formation, South of the Kashan, Central Iran

作者：Mohammadi Ebrahim^*; Safari Amrollah; Vaziri Moghaddam Hossein; Vaziri Mohammad Reza; Ghaedi Mehdi

来源：Carbonates and Evaporites, 2011, 26(3): 255-271.

DOI：10.1007/s13146-011-0059-0

• Qom Formation
• Central Iran
• Kashan
• Oligo-Miocene
• Benthic foraminifera
• Planktonic foraminifera
• Open shelf
• Tethyan Seaway

Qom Formation (Oligo-Miocene marine deposits, Central Iran) in the South of Kashan, was studied in order to determine its microfacies and depositional environment. Thirteen microfacies (MF A-M) were distinguished based on petrography, sedimentological features, components distribution and present fauna. According to recognized microfacies and absence of gravity deposits, real and continuous reef, barrier and storm structures, carbonate platform of the Qom Formation in South of Kashan developed on an open shelf without effective barriers separating it from the sea. The co-occurrences of miliolids and planktonic foraminifera in planktonic microfacies is the reliable evidences for absence of any reefal, oolitic and bioclastic barriers in depositional environment, and deposition of the study section on an open shelf, as in the absence of barrier, currents removed miliolids to deeper parts of sea (basin). Three major depositional environments were identified in the Oligo-Miocene succession in the study section, on the basis of the distribution of the foraminifera and vertical facies relationships. They include inner shelf, middle shelf and proximal outer shelf. Inner shelf includes MF A-G and characterized by abundant imperforate foraminifera. Middle shelf comprises MF H-J and characterized by association of larger benthic foraminifera with hyaline wall. Proximal outer shelf includes MF K-M and characterized by the presence of planktonic foraminifera and absence of larger benthic foraminifera, as well as abundance of light-independent, heterotroph organisms.

• 出版日期2011-10