针对东海陆架盆地西湖凹陷保俶斜坡带平北地区宝石组—平湖组下段（以下简称平下段）沉积微相类型及砂体展布特征不明确的问题，该研究利用古地貌、生物遗迹、微量元素、井-震结合手段及现代沉积类比等多种方法开展了沉积微相类型、时空演化及圈闭模式分析。研究表明：平北地区宝石组—平下段处于强烈断陷期，古地貌呈深凹高隆构造格局，对沉积体系具有较强的控制作用。宝石组物源来自北部虎皮礁隆起的岩浆岩，平下段西侧海礁隆起物源供给逐步增强，形成双物源格局。微量元素分析认为：平湖组、宝石组沉积时期为干热古气候，整体属于海陆过渡、贫氧沉积环境。宝石组—平下段发育4个三级层序，为逐渐水进过程。综合岩心相、测井相及生物遗迹相分析，宝石组—平下段发育潮汐三角洲、潮坪相、海相3种沉积相及水下分支河道、席状砂、河口坝、潮汐水道、砂坪、混合坪、泥坪、支流间湾、海湾泥9种沉积微相。广泛发育的潮坪相为主要的沉积相类型，斜坡近凹带发育树状涨潮及退潮三角洲、潮道、潮汐砂坝沉积，明确了宝石组—平下段5种控砂模式，包括堑-垒型、隆起-断坡型、多断坡型、转换带型及挠曲坡折型控砂模式，总结了5种圈闭类型，包括堑-垒型构造圈闭、隆起-断坡型构造圈闭、多断坡型构造-岩性复合圈闭、转换带型构造-岩性复合圈闭、挠曲坡折型岩性圈闭。斜坡内带的平湖组、宝石组发育海湾环境下多类型规模砂体，受挠曲坡折控制易形成岩性集中尖灭；砂体经潮流和波浪淘洗为纯净细砂岩，抗压实能力较强，易形成“甜点”储层，整体成藏条件优越，为下步勘探指明方向。

To address the unclear sedimentary microfacies types and sandbody distribution characteristics in the Baoshi Formation-lower member of Pinghu Formation (hereinafter referred to as lower Pinghu member) in the Pingbei area of the Baochu slope belt, Xihu Sag, East China Sea Shelf Basin, the study employed a comprehensive approach combining paleogeomorphology, biological traces, trace element analysis, well-seismic integration, and modern depositional analogs to analyze the sedimentary microfacies types, spatiotemporal evolution, and trap models. The research indicated that the Baoshi Formation-lower Pinghu member in the Pingbei area was in the intense rift period, with a paleo-geomorphologic pattern characterized by deep depressions and high uplifts, exerting a strong control on the sedimentary system. The Baoshi Formation was sourced from magmatic rocks in the northern Hupijiao uplift, while sediment supply from the Haijiao uplift in the western lower Pinghu member gradually increased, forming a dual-provenance system. Trace element analysis indicated that the deposition of the Pinghu and Baoshi Formations occurred under an arid and hot paleoclimate in a generally suboxic, marine-continental transitional environment. Four third-order sequences were developed in the Baoshi Formation-lower Pinghu member, representing a progressive marine transgression. Integrated analysis of core facies, logging facies, biofacies, and ichnofacies revealed that the Baoshi Formation-lower Pinghu member developed three sedimentary facies (tidal delta, tidal flat facies, and marine facies) and nine microfacies (subaqueous distributary channels, sheet sands, mouth bars, tidal channels, sand flats, mixed flats, mud flats, interdistributary bays, and bay mud). The extensively developed tidal flat facies was the dominant sedimentary facies type. Dendritic flood and ebb tidal deltas, tidal channels, and tidal sand bars developed near the slope depression belt. Five sand-controlling models were identified in the Baoshi Formation-lower Pinghu member: graben-horst type, uplift-fault slope type, multiple fault slope type, transfer zone type, and flexural slope break type. Five trap types were summarized: graben-horst structural traps, uplift-fault slope structural traps, multiple fault slope structural-lithological composite traps, transfer zone structural-lithological composite traps, and flexural slope break lithological traps. Within the inner slope zone, the Pinghu and Baoshi Formations developed large-scale sand bodies under bay environments, which were prone to lithologic pinch-out controlled by flexural slope breaks. Tidal and wave reworking produced clean fine sandstones with strong compaction resistance, forming favorable “sweet spot” reservoirs. Overall, the inner slope zone possesses excellent accumulation conditions. The research findings provide clear directions for future exploration.