The genetic type of siliceous minerals exerts differential controls on shale reservoir quality;however,current reservoir evaluation frameworks predominantly employ total quartz content as a proxy,neglecting the distinct reservoir effects associated with silica of different origins. This study systematically investigates the silica origin,genesis,and geological significance of Permian shales from the Wujiaping Formation Member 2(Wu-2 Member)and Maokou Formation Member 4(Mao-4 Member)in the Hongxing area,eastern Sichuan Basin,using an integrated approach combining scanning electron microscopy with energy-dispersive spectroscopy(SEM-EDS),X-ray diffraction(XRD),and major-trace element geochemistry. The key findings are as follows: (1)Both members contain detrital quartz and biogenic quartz-the latter encompassing structurally preserved(radiolarian fossils)and structurally recrystallized(microcrystalline quartz aggregates)varieties-while hydrothermal silica is absent. The Wu-2 Member is characterized by mixed detrital-biogenic silica(absolute detrital silica content: 21.7%;absolute biogenic silica content: 21.22%),whereas the Mao-4 Member is dominated by biogenic silica(absolute content 20.71%)with negligible detrital input(absolute content 3.34%).(2)Two contrasting silica enrichment models are proposed: a “superimposed enrichment model” for the Wu-2 Member,where deep-water shelf conditions sustained both substantial terrigenous supply and elevated bioproductivity;and a “carbonate dilution-controlled model” for the Mao-4 Member,where pervasive carbonate minerals accumulation overwhelmingly diluted siliceous components,passively elevating the relative proportion of biogenic silica.(3)Biogenic silica content serves as positive effects for evaluating organic matter enrichment,pore preservation,and reservoir fracability. Shifting the target window in the Hongxing area from carbon-rich,medium-silica lithofacies to carbon-rich,high-silica lithofacies increased daily test gas production from 11.67×10⁴ m³ to 26.64×10⁴ m³,demonstrating the pivotal role of biogenic silica content in engineering sweet-spot selection. A comprehensive evaluation framework integrating different genetic silica content and rock mechanical parameters is therefore recommended to guide precise layer selection and efficient development of Permian shale gas in the eastern Sichuan Basin.