Analysis of Diagenetic Systems of the Carbonate Deposits of the Ilam Formation (Khorramabad Anticline) Based on Elemental Geochemistry

Articles in Press

Document Type : Research Paper

Authors

1 ssist. Prof., Department of Geology, Faculty of Sciences, University of Gonabad, Gonabad, Iran

2 Assist. Prof., Department of Geology, Faculty of Sciences, University of Gonabad, Gonabad, Iran

3 PhD Graduate, Central Laboratory Expert of Lorestan University, Khorramabad, Iran

Abstract

The aim of this study is to investigate the original mineralogy and the type of diagenetic systems of the carbonate units of the Ilam Formation (Cretaceous) in the Khorramabad Anticline. In this section, the Ilam Formation has a thickness of 121 meters and consists of fine-grained argillaceous limestones. Its lower boundary with the Surgah Formation is disconformable and stained with iron oxide, while its upper boundary with the Gurpi Formation is conformable. In this study, 14 samples were analyzed using the EDX method. The trend of Sr versus Na and Mn variations shows that the studied samples fall within or adjacent to the field of aragonitic limestones of Gordon, Tasmania, but follow a similar trend. The trend of Mn versus Sr variations in the studied samples indicates that these samples fall within the same field as the original aragonitic mineralogy of the Mozduran Formation limestones, which is evidence for an original aragonitic mineralogy of the Ilam Formation limestones in the studied section. The low Sr/Mn ratio (mean 18.42 ppm) and Sr/Ca ratio (mean 11.94 ppm), the low Fe (mean 79.14 ppm) and Mn (mean 39.43 ppm) values, the relatively high Sr concentration (mean 424.14 ppm) in the studied samples, and the plotting of Sr/Ca versus Mn, Mg, and Fe values indicate a closed to slightly open diagenetic system with low to medium water–rock exchange for the carbonates of the Ilam Formation.

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Journal of Stratigraphy and Sedimentology Researches

Articles in Press, Accepted Manuscript
Available Online from 15 July 2026

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