"Exploring Iran's Khalij Limestone: In-depth Analysis of Gadvan Formation"

What is it about?

The focus of this study is on the Khalij limestone member, a distinctive layer within the Gadvan shaly formation. Despite its subterranean existence without exposed outcrops, this layer is notable for its benthic facies, measuring approximately 14 meters thick. Employing well logging techniques like Gamma Ray and Density measurements, researchers effectively identify this specific member. The primary goal of the study involves a comprehensive analysis of lithostratigraphy and microstratigraphy within the Gadvan formation, with a specific emphasis on the Khalij limestone member. The research spans a vast region of around 100,000 square kilometers in the Zagros region, particularly focusing on the Fars and Dezful areas. The study utilizes data from 38 exploration and development wells alongside meticulous examination of about 1,400 microscopic thin sections from the Gadvan formation. A significant outcome of this research is the establishment of a representative type section for the Khalij limestone member, characterized by a thickness of 13 meters. Through detailed microscopic analysis, it is revealed that this layer is predominantly composed of wackestone carbonate, housing microfossils, particularly foraminifera from the orbitolindae family. Based on species index observations, the Khalij limestone member is determined to be of Barremian age, associated with a lagoon-like depositional environment.

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Photo by Fineas Anton on Unsplash

Photo by Fineas Anton on Unsplash

Why is it important?

The significance of this study lies in its comprehensive analysis of the lithostratigraphy and microstratigraphy within the Gadvan formation, specifically focusing on the Khalij limestone member. Understanding this distinct layer, which is solely subsurface without exposed outcrops, holds crucial importance in geological assessments. The Khalij limestone member, known for its abundant benthic facies and identifiable orbitolinid limestone, presents challenges due to its hidden nature. Utilizing effective well logging techniques such as Gamma Ray and Density measurements becomes pivotal in identifying and understanding this layer. Covering a substantial area of about 100,000 square kilometers in the Zagros region, this research amalgamates data from numerous exploration and development wells along with meticulous examination of microscopic thin sections from the Gadvan formation. The pivotal contribution of this study is the establishment of a representative type section for the Khalij limestone member, providing crucial insights into its composition and characteristics. The detailed microscopic analysis reveals its predominant wackestone carbonate makeup and the presence of microfossils, particularly foraminifera from the orbitolindae family. Determining its Barremian age and association with a lagoon-like depositional environment adds significant value to understanding the geological history and depositional settings of this region. In summary, this research's significance lies in shedding light on an elusive subsurface layer, providing valuable insights into its composition, age, and depositional environment. Such knowledge is integral for regional geological assessments and understanding the complexities of the Gadvan formation within the Zagros region.

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