New Pattern of Uplift‐Depression of the Pre‐Cambrian Basement in the Sichuan Basin: Constraints From Multi‐Seismic Parameter Imaging

• Published in: Journal of geophysical research. Solid earth Vol. 130; no. 6
• Main Authors: Wang, Zhi, Du, Qiuding, Wang, Jian, Wen, Yinyu, Zhou, Gang, He, Yuan, Fu, Xiugen
• Format: Journal Article
• Language: English
• Published: 01.06.2025
• Subjects: multi‐parameter seismic tomography; pattern of uplift‐depression structure; potential hydrocarbon reservoirs; pre‐Cambrian basement; sichuan basin
• ISSN: 2169-9313; 2169-9356
• DOI: 10.1029/2024JB030152

The structural configuration of the pre‐Cambrian basement in the Sichuan Basin, a highly promising region for hydrocarbon exploration, has been a subject of long‐standing debate. Here, we determined the fine‐scale three‐dimensional seismic models of the Sichuan Basin using 187,356 high‐quality P‐ and S‐wave travel time pairs recorded by 627 recently installed seismic stations. Meanwhile, 595 petroleum wells were collected to investigate their spatial distribution associated with the basement structures. Our findings reveal two depression belts, one extending through the western regions of Chengdu, Mianyang, and Wanyuan, and another in the eastern regions of Wanzhou, Fuling, and Chishui, forming a distinctive horseshoe‐shaped depression structure. Concurrently, the central and southwest regions exhibit two uplift zones, constituting an L‐shaped uplift structure. Approximately 76% of the petroleum wells are situated within the L‐shaped uplift structure and its slope, while around 21% of the gas wells are located in the transitional zones between the depression structures or along their edges. The development of the depression structure is attributed primarily to the complex triple collision system involving the Qinghai‐Tibet block in the west, the Cathsysia block in the southeast, and the North China block in the north. Conversely, the uplift structure is mainly caused by the southeastward movement of the Songpan‐Ganze block and the northwestward movement of the Cathsysia block. These new findings reveal a significant correlation between the paleo‐uplift structures, the distribution of hydrocarbon resources, and the geological conditions conducive to petroleum reservoirs in the Sichuan Basin, providing valuable insights for predicting potential petroleum reservoirs. Plain Language Summary The Sichuan Basin is widely recognized as a promising area for hydrocarbon reservoirs in China. Understanding the structural configuration of its pre‐Cambrian basement is crucial for hydrocarbon exploration. Here, we utilized a joint tomographic method to resolve high‐resolution crustal structures of seismic velocities (Vp, Vs) and Poisson's ratio (σ). Using unprecedented P‐ and S‐wave travel‐time pairs from hundreds of recently deployed seismic stations across the Sichuan Basin and its surroundings, we identified a novel structural pattern of an L‐shaped uplift and a horseshoe‐shaped depression. These features delineate a tectonic framework comprising two depressions and one uplift within the pre‐Cambrian basement. Analyzing the spatial distribution of petroleum wells indicates that approximately 76% of the oil and gas wells are located within the L‐shaped uplift belt and its slope, while 21% of the gas wells are situated in the transitional zones between the depression structures or along their edges. These new findings provide valuable insights for predicting potential hydrocarbon reservoirs in the Sichuan Basin.