Petrography, sedimentary environment and microfacies of the Fahlian Formation in the Gachsaran field
Subject Areas : Earth SciencesSara Maleki kheymehsari 1 , Ali Talebi Basari 2
1 - Department of Geology, Be.C., Islamic Azad University, Behbahan, Iran
2 - Department of Geology, Be.C., Islamic Azad University, Behbahan, Iran
Keywords: : Fahlian Formation, microfacies, sedimentation model, Gachsaran field,
Abstract :
The Fahlian Formation in the Gachsaran field, one of the most important carbonate formations in southwestern Iran, is composed of diverse microfacies and diagenetic processes. The study of different microfacies has led to the identification of open marin, bar, lagoon and tidal flat. In the open marin environment, two microfacies have been identified. First, sponge spicule and radiolarian wackstone and second, bioclast wackstone and sponge spicule. In the bar facies belt, three microfacies have been identified. Intraclast, eoid greenstone and second eoid, agglomerate greenstone and third, bioclast, ploid greenstone. In the lagoon area, three microfacies have been identified. bioclast, ploid paxton and second benthic foraminifera, dasiclade wackstone and third small fossiliferous mudstone. In the tidal flat, two microfacies have been identified. Greenstone intraclast and mudstone facies containing silt-like detrital particles. The depositional model of the Fahlian Formation in the Gachsaran field is formed on a shallow ramp-type carbonate platform. Four tidal facies belts, lagoonal facies, dam facies, and open-sea facies, have been identified in this sedimentary model. The presence of dam-forming eoid and ploidy facies indicates that this carbonate sequence was deposited on a marginal carbonate platform (shelf). Various diagenetic processes have been identified in the Fahlian Formation, which generally include micrinization, cementation, dolomitization, silicification, porosity, and dissolution. Among these processes, micrinization and cementation are more prominent, especially in lagoonal and dam facies.
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