Aptian siliciclastic onshore deposits of the Mucuri Member are important reservoirs in the Espírito Santo Basin (eastern Brazil). A detailed quantitative petrographical and textural analysis of well core samples was performed in order to unravel their depositional processes and conditions, in relation to previously proposed depositional models. The results allowed differentiation between two groups of sandstone samples, characterized by different textural characteristics associated to different depositional processes and environments within the Mucuri depositional system. Fluvial sandstones are represented by medium- to coarse-grained, poorly sorted arkoses, rich in plutonic rock fragments and feldspar grains, mainly transported by traction. Coastal-lacustrine sandstones correspond to very fine- to fine-grained, moderately sorted micaceous arkoses, mainly transported in suspension. The application of a discriminant function based on grain-size parameters validated previously proposed depositional settings for the studied sample groups. The combination of grain-size and shape data revealed differences in hydraulic equivalence and shape between grains from different depositional settings. In terms of hydraulic equivalence, micas in the fluvial sediments present lower settling velocity values, in contrast to the relatively large mica grains in the coastal sediments, which are hydraulically equivalent with the associated quartz and feldspar grains. The results of this study provide key information regarding depositional conditions (transportation mechanisms, grain-settling velocity and mineral hydraulic fractionation) at the margins of the Aptian pre-salt system, which can constrain the hydrological conditions and the sediment type available for distal lacustrine areas.

Mucuri 段的 Aptian 硅质碎屑陆上矿床是 Espírito Santo 盆地（巴西东部）的重要储层。对井芯样品进行了详细的定量岩相和结构分析，以了解与先前提出的沉积模型相关的沉积过程和条件。结果允许区分两组砂岩样品，其特征在于与 Mucuri 沉积系统内的不同沉积过程和环境相关的不同质地特征。河流砂岩以中粗粒、分选差的长石砂为代表，富含深成岩碎片和长石颗粒，主要通过牵引运移。沿海湖相砂岩对应于极细到细粒、中等分选的云母长石，主要以悬浮方式运输。基于粒度参数的判别函数的应用验证了先前为研究样品组提出的沉积设置。粒度和形状数据的结合揭示了来自不同沉积环境的颗粒之间的水力当量和形状的差异。就水力当量而言，河流沉积物中的云母呈现较低的沉降速度值，与沿海沉积物中相对较大的云母颗粒形成对比，后者与相关的石英和长石颗粒在水力上等效。这项研究的结果提供了关于 Aptian 盐下系统边缘沉积条件（运输机制、颗粒沉降速度和矿物水力分馏）的关键信息，