Interpretation of diagenesis history of carbonate rocks of the Asmari Formation (Oligocene-Miocene), southwestern of Lorestan

Articles in Press

Authors

1 M. Sc. Student, Department of Petroleum Engineering, Mashhad Branch, Islamic Azad University, Mashhad, Iran

2 Associate Professor, Department of Petroleum Engineering, Mining and Geology, Mashhad Branch, Islamic Azad University, Mashhad, Iran

3 Department of Petroleum Engineering, Mining and Geology, Mashhad Branch, Islamic Azad University, Mashhad, Iran

Abstract

In order to interpret the diagenesis sequences and the post-depositional history of the carbonate rocks of the Asmari Formation, a 131-meter-thick stratigraphic section located in the Rit anticline (south-western Lorestan) has been studied and sampled. The lithology of this formation is a period of carbonate and dolomite carbonate rocks. The results of the study of sedimentary thin sections showed that several diagenesis processes occurred in the Asmari Formation. These processes include micrite coating, cementation, dissolution, porosity, physical and chemical compression and all kinds of successions that have been formed in four environments: marine, fresh water, burial and upwelling. Three stages of initial (eugenesis), intermediate (mesogenesis) and final (telogenesis) diagenesis have been determined for the studied deposits. Petrological and elemental geochemical studies on dolomitic carbonate units led to the identification of two groups of dolomites in this formation (primary and secondary dolomites). The concentration of secondary elements (Fe and Mn) in primary dolomites is the lowest, while the concentration of these elements in secondary dolomites is the highest. Also, the concentration of other secondary elements such as (Sr and Na) is the highest in primary dolomites, while the concentration of these elements in secondary dolomites is the lowest, which indicates a shallow to medium burial diagenesis environment for it has secondary complications. The dolomites of this formation have not yet reached the crystalline order (stoichiometry), which can be due to the young age of these deposits (Oligocene-Miocene) in the region.

Keywords

Applied Sedimentology

Articles in Press, Accepted Manuscript
Available Online from 13 January 2025

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History

  • Receive Date: 25 October 2024
  • Revise Date: 12 January 2025
  • Accept Date: 13 January 2025

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