Relative dating of deposits of the Mishan Formation based on foraminifera and Strontium isotope in northwest and west of Bandar Abbas, south Iran

Abstract

For studying of biostratigraphy of Mishan Formation in Bandar Abbas hinterland, a stratigraphic transection including Handun, Anguru, Baviyun, and Nakh sections was selected in northwest and west of Bandar Abbas. A total 668 samples investigated from Mishan Formation which 515 hard and 153 soft samples. The Mishan Formation consists mainly of massive to thin bedded limestones and thin bedded argillaceous limestone and green to grey marls. The Guri Member at the bottom of the Mishan Formation, overlies siliciclastic rocks of the Razak Formation or evaporate deposits of Gachsaran Formation and lie under the brown conglomerate and sandstone of the Agha Jari Formation. Generally, at the base of sections, based on presence of benthonic foraminifera such as Meandropsina iranica, Meandropsina anahensis, Borelis melo curdica the age of sections was determined as Burdigalian and only at 17 m of base of Nakh section due to absence of Burdigalian index foraminifera, belongs to Aquitanian which it corresponds to the strontium isotope analysis. The age of upper parts of the sections due to the presence of planktonic foraminifera such as Praeorbulina glomerosa, Orbulina suturalis, Orbulina universa, is suggested Langhian. Burdigalian age was determined based on foraminifera contents only in stratigraphic section of Nakh, that corresponds to the strontium isotope analysis. In this study, planktonic foraminifera taxa such as O. universa, O. suturalis, P. transitoria and P. glomerosa are reported for the first time from Guri Member in Handun section. Keywords: Mishan Formation, Biostratigraphy, Foraminifera, Strontium isotope, Burdigalian – Langhian, Bandar Abbas hinterland

Keywords

• Mishan Formation
• Biostratigraphy
• Foraminifera
• Strontium isotope
• Burdigalian – Langhian
• Bandar Abbas hinterland