Analysis of Structure and Textures of Anhydrite Mineral in Gachsaran Formation in Gotvand Area, Iran

Abstract

Minerals are deposited when evaporation is greater than atmospheric precipitation. Calcium sulfates are one of the most important evaporative minerals which have been expanding over the past few years. In the formation of these minerals, various sedimentary and diagenetic processes play a role from shallow ridges to deep water. The research investigated the types of evaporative minerals (with an emphasis on anhydrite) in Gachsaran Formation in Gotvand dam range (25 km north of Shoushtar city). Investigating the thin sections of evaporative samples of this formation led to the identification of various anhydrite textures. Also, the existence of the main phases of calcium sulfate and NaCl by XRD analyses on a number of samples. The formation of anhydrite, gypsum and halite minerals in Gachsaran Formation in Lagoon and Sabkha environments was identified texture. The most important textures were laths anhydrite, nodule, isolated, radial anhydrite crystals, and porphyroblastic gypsum crystals, most of which are formed at the same stage of precipitation or in the early stages of diagenesis.