Laminar controls on bedding-parallel fractures in Permian lacustrine shales, Junggar Basin, northwestern China

• DOI: 10.1130/b37792.1
• Publication Date: 2025-03-10T17:23:39Z
• Authors: Guoping Liu; Zhijun Jin; Lianbo Zeng; Xiaoxuan Chen; Mehdi Ostadhassan; Qiqi Wang; Guoqing Lu; Xiaoyu Du
• Keywords: Bedding; Bed

The lamina-rich structures formed during slow sedimentation in lacustrine shales are the foundation for widespread development of bedding-parallel fractures (BPFs). Considering differences type, composition, and characteristics laminae, BPFs developed following various tectonic diagenetic evolutions that exhibit significant heterogeneity. This study analyzed multi-scale data from Permian Fengcheng Formation Junggar Basin northwestern China to understand how laminae control BPF initiation growth. results show fine-grained mixed would develop most with large lateral extensions, which is attributed their enriched organic matter clay minerals fostering outstanding stratification being conducive evolution enhance rock cohesion. In felsic carbonate dissolution change mineral crystal lattice more BPFs, while these alkali less easily pinched out. Moreover, variations arrangement, size lead apparent mechanical anisotropy weak plane at lamina interfaces, promote formation extent BPFs. Additionally, hydrocarbons produced thermal degradation cracking generate abnormally high pore fluid pressure, instigates vertical seepage force a tensile stress state contributes fracture formation. Consequently, degree content positively correlated. These insights into controls on can provide theoretical basis revealing mechanism elucidating patterns shales.