Morphological characteristics of framboidal pyrite and their paleo-environmental significance in Longmaxi Formation of Weirong area, southern Sichuan Basin

• Published in: Shi you shi yan di zhi Vol. 47; no. 2; pp. 261 - 272
• Main Authors: Guowei ZHAO, Mo DENG, Yuanzheng WANG, Xiaoqiong JIANG, Huasheng ZENG, Changjiang ZHANG
• Format: Journal Article
• Language: Chinese
• Published: Editorial Office of Petroleum Geology and Experiment 01.03.2025
• Subjects: framboidal pyrite; longmaxi formation; redox environment; sedimentary environment; shale gas; southern sichuan basin; weirong area
• ISSN: 1001-6112
• DOI: 10.11781/sysydz2025020261

The morphological characteristics of framboidal pyrite have important indicative significance for the shale sedimentary environments and shale gas enrichment. Taking the shale in the first member of the Longmaxi Formation from well WY1 in the Weirong area of southern Sichuan Basin as the study subject, argon ion scanning electron microscopic analyses and ImageJ image processing were conducted to obtain the morphological characteristics and particle sizes of framboidal pyrite and its microcrystals. By analyzing parameters such as trace elements, organic matter abundance, and gas content, the study explored the indicative role of framboidal pyrite morphology in paleo-water redox environments and shale gas enrichment. The results demonstrated that parameters such as the average particle size of framboidal pyrite, the average particle size of microcrystals, and the crystalline structures showed significant variations vertically. The average particle sizes of pyrite and its microcrystals were 4.02 μm and 0.45 μm,