The origin of siliceous material in dolostones of the Upper Cambrian Lower Qiulitage Formation in the western margin of Northern Tarim Basin was investigated using germanium/silicon (Ge/Si) ratios together with major- and trace-element geochemistry. The dolostones contain 65.40%–99.49% SiO₂ (mean value > 90%) and yield Ge/Si ratios of 0.12–2.74 μmol/mol (mean value = 0.54 μmol/mol), far below typical hydrothermal end-member values of 4–25 μmol/mol; samples close to the Mana igneous body show elevated ratios. Ge/Si correlates positively with Fe₂O₃ but shows no relationship with Al₂O₃. Taken together, the low Ge/Si ratios and low Al₂O₃ contents indicate that the silica precipitates mainly from residual seawater and is subsequently overprinted, to a limited extent, by hydrothermal fluids that produced vein-hosted aggregates. Al₂O₃ contents increase systematically from east to west across the study area, pointing to a westward decrease in hydrodynamic energy that favours the accumulation of fine-grained terrigenous detritus on the restricted platform. These findings place important geochemical constraints on the silica provenance and diagenetic history of the Lower Qiulitage dolostone reservoirs and have implications for deep hydrocarbon exploration.

基于锗/硅比值(Ge/Si), 结合主量和微量元素含量等地球化学指标, 探讨塔北地区西部上寒武统下丘里塔格组白云岩中硅质沉积的成因。结果表明, 白云岩中SiO₂含量为65.40%~99.49% (平均值>90%), Ge/Si值为0.12~2.74 μmol/mol (平均值为0.54 μmol/mol), 显著低于热液端元值(4~25 μmol/mol), 靠近马纳火成岩体的样品Ge/Si值升高; Ge/Si值与Al₂O₃含量无相关性, 但与 Fe₂O₃含量正相关。低Ge/Si值及低Al₂O₃含量指示硅质主体为残余海水沉淀, 后期受一定程度的热液流体改造作用, 形成脉状集合体。研究区西部样品中Al₂O₃含量普遍高于东部, 揭示自东向西水动力减弱, 导致细粒陆源碎屑在局限台地富集。研究结果可以为厘清研究区下丘里塔格组白云岩储层中硅质的来源和成岩演化提供关键的地球化学约束, 对深层油气勘探具有指导意义。