Gachsaran Formation, Part 1: History of the Development of Lithostratigraphy divisions and Gachsaran Formation Key Beds in Dezful Zone

Document Type : Original Article

Author
JAVAD SAADATNEJAD
Petroleum Geology Office, Exploration Directorate, National Iranian Oil Company
10.30470/zpaleo.2023.708627
Abstract
Gachsaran Formation was named as lower Gypsum Group at first, then lower Fars Series and finally Gachsaran Formation. The subdivision of Gachsaran Formation, due to its importance during drilling operations, has long been of interest to many geologists. Therefore more accurate and practical definitions have been provided over the years. At first, Gachsaran Formation as a lower Fars Series divided into three parts; Stage I (equivalent to members 1-5), Stage II (equivalent to member 6) and Stage III (equivalent to member 7). Finally, Gachsaran Formation divided into seven members (member 7 on top and member 1 or cap rock in the base of Gachsaran Formation). During the past years, different geologists have proposed different key beds in the whole thickness of Gachsaran Formation from different anticlines. However currently only 6 key beds in the cap rock are used as A, B, C, D, E & F. In order to ensure the definitions and determine the Lithostratigraphic characteristics of sections, all existing anticlines in Dezful zone (Northern, Southern and Abadan plain) were investigated.
Keywords
Gachsaran Formation
Lithostratigraphy
Key beds
Dezful Zone
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