Abstract: Subsurface brine in the Zigong area of the Sichuan Basin contains salt and is also enriched in critical metal lithium, primarily occurring in the axial parts of anticlines. After years of exploitation, the Zigong area is now facing scarce brine resources and difficulty in reserve replacement. Fold flanks in the area may hold considerable resource potential; however, there is a lack of studies on deep brine exploration along fold flanks. This study investigated deep subsurface brine in the Tiejianggou and Xiangyangwan zones, which are located along anticlinal and synclinal flanks in the Zigong area, respectively. Petrophysical investigation and wide-field electromagnetic exploration reveal significantly varying deep electrical properties in both zones. Based on stratigraphic and structural constraints, this study performed comprehensive interpretations of deep electrical structures and low-resistivity anomalies in both zones. The results indicate that a 1500-m-deep profile in both zones exhibits significant electrical zonation characterized by low resistivity in the upper part and high resistivity in the lower part. The interval spanning from the lower part of the Xujiahe Formation to the upper part of the Leikoupo Formation is identified as a favorable exploration target. Layered, quasi-layered, or elliptical low-resistivity anomalies are identified in both zones, corresponding well to the occurrence horizons of regionally proven yellow brine. Drilling results of the Tiejianggou zone further verify the reliability of the geological anomaly interpretation. The findings lead to the conclusion that fold flanks also exhibit favorable conditions for the enrichment and preservation of subsurface brine, representing an important replacement for deep brine prospecting in the Zigong area. The results of this study provide novel insights for both resource exploration in the periphery of mature salt-producing areas and the investigation of the occurrence patterns of subsurface brine.