Present-Day Structural Deformation and Stress Regime in the Southern Sichuan Basin, China: Insights From Deep Geophysical Data and Numerical Modelling

Abstract

The Sichuan Basin, adjacent to the Himalayas in China, exhibits complex structural deformation and stress regimes, necessitating systematic structural and stress analysis. The Luzhou region in the southern Sichuan Basin is cut by three sets of faults, which trend NNE (NE)–SSW (SW), E (NEE)–W (SWW), and N (NNW)–S (SSE). Late Ordovician to early Silurian strata lie between the basement and cover sequences, and the faults are mainly extrusion thrust faults. Integrated geophysical data and finite element numerical modelling reveal that the maximum horizontal principal stress (S_H) is 76–131 MPa, the minimum horizontal principal stress (S_h) is 64–113 MPa, and the vertical stress (S_v) is 69–125 MPa, consistent with a strike-slip regime (S_H > S_v > S_h). Consequently, the present-day stress regime differs from that of existing thrust-fault models. The NNE (NE)–SSW (SW) trending faults have the greatest impact on the magnitude and orientation of the stress, and the E (NEE)–W (SWW) faults have the greatest impact on the horizontal stress differences (ΔS). ΔS is negatively correlated with the total gas content and negatively correlated with borehole deformation in seven wells in the Luzhou region; therefore, E (NEE)–W (SWW) trending faults should be avoided during petroleum exploration in the Luzhou region.

Keywords

fault / finite element numerical modelling / in situ stress / Luzhou region / Sichuan Basin / structural deformation

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2026 Geological Society of China.