Ardebili Pooya Naghizadeh, Jozanikohan Golnaz, Moradzadeh Ali
School of Mining, College of Engineering, University of Tehran, Tehran, Iran.
Sci Rep. 2025 Mar 15;15(1):9000. doi: 10.1038/s41598-025-93930-5.
This study focuses on the identification of type, abundance, and distribution patterns of the clay minerals within the Kashafrud Formation, a Middle Jurassic sedimentary rock sequence in the Khangiran gas field, Kopet-Dagh Basin, northeast Iran. This investigation shed light on the identification of type, abundance, and distribution patterns of the clay minerals obtained from 10 representative core samples by employing laboratory techniques, such as powder X-ray diffraction, polarizing light microscopy, and scanning electron microscopy. Results from the XRD analysis revealed quartz as the dominant mineral (49-65%), accompanied by the clay minerals (illite 8-18%, kaolinite 2-6%, chlorite 3-11%), alkali feldspar (7-16%), and plagioclase (3-10%), with occasional presence of ankerite (2-7%) or pyrite (1-3%). Polarizing light microscopy indicated a composition mainly of quartz and feldspar grains, categorized as arkose. Furthermore, the SEM studies highlighted that the pore filling pattern as the prevailing distribution pattern of clay minerals with occasional instances of pore coating pattern. The clay portion of each sample was separated and analyzed by an electron microscope device that identified silicon, oxygen, and aluminum as the primary elements. Furthermore, the findings of this study showed the average weight percentages of clay minerals, including kaolinite, chlorite, and illite in the mentioned formation were 4.3%, 7.4%, and 11.1%, respectively, contributing to an overall clay mineral content of 23.7%. The presence of illite, kaolinite, and chlorite could lead to a significant formation damage. Eventually, the observed distribution pattern and clay mineral content suggest the Kashafrud Formation leans towards a predominantly shaly-sand composition.
本研究聚焦于伊朗东北部科佩特 - 达格盆地康吉兰气田的中侏罗世沉积岩层卡沙夫鲁德组内粘土矿物的类型、丰度和分布模式。通过采用粉末X射线衍射、偏光显微镜和扫描电子显微镜等实验室技术，对从10个代表性岩芯样本中获取的粘土矿物的类型、丰度和分布模式进行了鉴定。XRD分析结果显示石英为主要矿物（49 - 65%），伴有粘土矿物（伊利石8 - 18%、高岭石2 - 6%、绿泥石3 - 11%）、碱性长石（7 - 16%）和斜长石（3 - 10%），偶尔还有铁白云石（2 - 7%）或黄铁矿（1 - 3%）。偏光显微镜表明其成分主要为石英和长石颗粒，归类为长石砂岩。此外，扫描电子显微镜研究突出了孔隙填充模式是粘土矿物的主要分布模式，偶尔有孔隙涂层模式的情况。每个样本的粘土部分被分离出来，并用电子显微镜设备进行分析，该设备确定硅、氧和铝为主要元素。此外，本研究结果表明，上述地层中高岭石、绿泥石和伊利石等粘土矿物的平均重量百分比分别为4.3%、7.4%和11.1%，粘土矿物总含量为23.7%。伊利石、高岭石和绿泥石的存在可能导致显著的地层损害。最终，观察到的分布模式和粘土矿物含量表明卡沙夫鲁德组倾向于主要为泥质砂岩成分。
