Provenance, Tectonic Setting and Geochemistry of Ahwaz Sandstone Member （Asmari Formation, Oligo-Miocene）, Marun Oilfield, Zagros Basin, SW Iran

• Published in: 地质学报：英文版 2014, Vol.88 (3), p.931-948
• Main Author: Shahram AVARJANI Asadollah MAHBOUBI Reza MOUSSAVI-HARAMI Hassan AMIRI-BAKHTIAR
• Format: Article
• Language: English
• Subjects: 中新世; 前陆盆地; 化学风化程度; 地球化学; 构造背景; 油田; 砂岩段; 种源
• ISSN: 1000-9515; 1755-6724

The Asmari Formation deposited in the Zagros foreland basin during the OligoceneMiocene.Lithologically,the Asmari Formation consists of limestone,dolomitic limestone,dolomite,argillaceous limestone,some anhydrite （Kalhur Member） and sandstones （Ahwaz Member）.This study is based on the analysis of core samples from four subsurface sections （wells Mn-68,Mn-281,Mn-292 and Mn-312） in the Marun Oilfieid in the Dezful embayment subzone in order to infer their provenance and tectonic setting of the Ahwaz Sandstone Member.Petrographical data reveal that the Ahwaz Sandstone comprises 97.5% quartz,1.6% feldspar,and 0.9% rock fragments and all samples are classified as quartz arenites.The provenance and tectonic setting of the Ahwaz Sandstone have been assessed using integrated petrographic and geochemical studies.Petrographic analysis reveals that mono-and poly-crystalline quartz grains from metamorphic and igneous rocks of a craton interior setting were the dominant sources.Chemically,major and trace element concentrations in the rocks of the Ahwaz Sandstone indicate deposition in a passive continental margin setting.As indicated by the CIW index （chemical index of weathering） of the Ahwaz Sandstone （average value of 82） their source area underwent ＂intense＂ recycling but ＂moderate to high＂ degree of chemical weathering.The petrography and geochemistry results are consistent with a tropical,humid climate and low-relief highlands.