The changes in the geometry, density and distribution of the fluvial reservoir sand-bodies have been modelled both in the laboratory and from outcrop analogues. On the other hand, fine-grained floodplain deposits, often called “background” sedimentation, have not been in the spotlight. However, they provide a very important database for fluvial architecture reconstruction and therefore constitute a key tool in characterizing, correlating and modelling heterogeneous fluvial reservoirs. The methodology used in this work combines classical sedimentological and palaeopedological data. Palaeosols were identified in outcrops of the Cretaceous of Patagonia and Triassic red beds of Spain based on the main pedofeatures such as colour, soil structures, mottles, nodules, clay illuviation cutans, slickensides and rhizoliths. Palaeosol horizons, thickness and types of contact were described. The palaeosols classification was made through the comparison with the Soil Taxonomy. For the characterization of lateral palaeosols variability, several palaeopedological logs were constructed following the same stratigraphic level at both margins of the main channels. Small-scale or high-frequency palaeosol variations, identified in both fluvial succession are represented by the lateral and vertical superimposition of Inceptisols/Entisols, Vertisols and hydromorphic Vertisols/swamp deposits. We recognized a decrease in the drainage conditions within the palaeosols catena moving away from the main channel bodies. The most waterlogged palaeosol is located at 200 to 300 m from the main channels. Lateral changes of palaeosols are interpreted as the result of intrinsic factors to the depositional systems, such as the relative position within the floodplain and the distance from the main channels, that condition the particle size of parent material, the sedimentation rate and the palaeotopographic position which state the drainage conditions of palaeosols. Vertical stacking of different palaeosols is linked to avulsion processes and the relatively abrupt change in the distance to main channels as the system aggraded. The study of these two environmentally similar examples (low-gradient meandering fluvial systems subjected to a high rate of aggradation), although located in different tectonic and chronostratigraphic contexts, shows that the type of fluvial system acted as the main control of sedimentary and pedogenic processes; as well as the scale at which they occur. Thus, when choosing an outcrop fluvial reservoir analogue, the type of fluvial system and climate should be more important than the age or the tectonic framework of the succession to be studied.

已在实验室和露头类似物中模拟了河流储层砂体的几何形状、密度和分布的变化。另一方面，细粒泛滥平原沉积物，通常被称为“背景”沉积物，并没有成为人们关注的焦点。然而，它们为河流构造重建提供了一个非常重要的数据库，因此构成了表征、关联和模拟非均质河流水库的关键工具。这项工作中使用的方法结合了经典的沉积学和古土壤学数据。根据颜色、土壤结构、斑驳、结核、粘土覆盖物、水滑石和根石等主要土壤特征，在巴塔哥尼亚白垩纪和西班牙三叠纪红层的露头中发现了古土壤。古土壤层，描述了接触的厚度和类型。古土壤分类是通过与土壤分类法的比较进行的。为了表征侧向古土壤的变异性，在主要河道的两个边缘按照相同的地层水平构建了几个古土壤学测井。在两个河流序列中确定的小规模或高频古土壤变化表现为 Inceptisol/Entisol、Vertisols 和水形 Vertisols/沼泽沉积物的横向和垂直叠加。我们认识到古土壤中的排水条件有所下降 在主要河道的两个边缘按照相同的地层水平建造了几个古土壤学日志。在两个河流序列中确定的小规模或高频古土壤变化表现为 Inceptisol/Entisol、Vertisols 和水形 Vertisols/沼泽沉积物的横向和垂直叠加。我们认识到古土壤中的排水条件有所下降 在主要河道的两个边缘按照相同的地层水平建造了几个古土壤学日志。在两个河流序列中确定的小规模或高频古土壤变化表现为 Inceptisol/Entisol、Vertisols 和水形 Vertisols/沼泽沉积物的横向和垂直叠加。我们认识到古土壤中的排水条件有所下降系列远离主要通道体。涝渍最严重的古土壤位于距主河道 200 至 300 m 处。古土壤的横向变化被解释为沉积系统内在因素的结果，如漫滩内的相对位置和与主河道的距离，这些因素决定了母质的粒度、沉积速率和古地形位置。说明古土壤的排水条件。不同古土壤的垂直堆积与撕脱过程以及随着系统的加剧与主要通道的距离的相对突然变化有关。研究这两个环境相似的例子（低梯度蜿蜒河流系统，受到高加成率），尽管位于不同的构造和年代地层环境，表明河流系统的类型是沉积和成土过程的主要控制；以及它们发生的规模。因此，在选择露头河流储层类似物时，河流系统的类型和气候应该比要研究的层序的年龄或构造框架更重要。