Biostratigraphy of the Gurpi Formation Based on Planktonic foraminifera in Gandab Section and it's comparison with Type section, Kabirkuh Anticline, SW Iran

• Main Authors: Samira Rahimi, Ali Reza Ashouri, Abbas Sadeghi, Abbas Ghaderi
• Format: Article in Journal/Newspaper
• Language: Persian
• Published: University of Isfahan 2018
• Subjects: biostratigraphy; planktonic foraminifera; gurpi formation; gandab section; ilam; Stratigraphy; QE640-699; Caron; Molla; Planktonic foraminifera
• Online Access: https://doi.org/10.22108/jssr.2018.112943.1068; https://doaj.org/article/b4f2d21058314f0ebfdc622dbfec69c7

Introduction Due to the source nature and placement of the Gurpi Formation between the Asmari and Bangestan reservoirs, it has a special importance. The name of this formation has been derived from Gurpi Mountain in the northwest of Masjid-Soleyman County. At the type section, this formation includes 320 meters of marl and bluish gray shales together with subordinate thin layers of clayey (argillaceous) limestone which overlies the limestones of the Ilam Formation, along an erosional unconformity. The Gurpi Formation has an open marine and deep sea sedimentation environment, which is why it is a good talent for biostratigraphy studies using planktonic fauna. Studies conducted by some researchers on the Gurpi Formation represent a Late Santonian – Tanetian age in different parts of the Zagros area, based on different planktonic assemblages (e.g., Kameli Azan et al., 2004; Darvishzadeh et al., 2007; Abrari et al., 2010; Senemari & Sohrabi Molla Usefi, 2012; Senemari & Azizi, 2012; Beiranvand et al., 2013; Najafpour et al., 2014; Fereydoonpoor et al., 2014; Razmjooei et al., 2014.). Materials and methods This study is based on macroscopic field description of 252 meters of Upper Cretaceous sequences (Gurpi Formation) in the Gandab section located on southern flank of Kabir Kuh anticline in Lurestan Province of Zagros, southwest Iran. In total, 192 hand specimens were taken from rock samples and sediments from these sections for paleontological study. After washing, samples were dried on sieves and put in special cellules. Released fossils were studied by binocular firstly, and then by Scanning Electronic Microscope (SEM). Determination and naming genera and species was based on Robaszynski et al. (1984), Caron (1985), Loeblich and Tappan (1988), and Premoli Silva and Verga (2004). Discussion of Results Biostratigraphy In this study, 57 species related to 20 genera and 7 biozones of planktonic foraminifers are recognized in Gandab section. - Globotruncana ventricosa Interval Zone This biozone is defined ...