Basin-wide analysis of an ancient distributive fluvial system (the upper Bima Formation) was carried out using field-based observation/measurement and ‘photo-realistic’ virtual outcrop data from 19 locations with good exposure of the upper Bima Formation in the Northern Benue Trough. The goal of this study is to provide an assessment of the spatial distribution of both vertical and lateral trends within the upper Bima distributive fluvial system. Vertical and lateral variations of the different facies of the formation were assessed quantitatively; this includes the analysis of the vertical and lateral distribution of proximal, medial and distal facies, the thickness and widths of channel fill deposits, grain-size variation and the proportion of floodplain to channel fill deposits across the 19 locations in the basin. Trends observed across the sections indicate a progradation of the mega-fan. The facies tracts preserved within the different portions of the distributive fluvial system vary. In the proximal part, in Lamurde, Tashan Alaji, Ture and Tula, the sections show only medial passing up to proximal facies. The distal lacustrine facies at the base of the section are absent. In the medial part of the system at Hinna, the successions preserve distal passing upward into medial facies. The gradual lateral transition from proximal to medial to distal facies, upward decrease in floodplain to channel fill deposits, upward increase in channel fill thicknesses and widths, all suggest that the Bima system is a prograding distributive fluvial system.

中文翻译：

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中白垩世分流河流系统的进积：尼日利亚贝努埃海槽北部比马组上段

使用基于现场的观察/测量和来自 19 个地点的“逼真”虚拟露头数据对古老的分布河流系统（上比马组）进行了全流域分析，这些地点对贝努埃北部的上比马组有良好的暴露槽。本研究的目的是评估上比马河流域系统中垂直和横向趋势的空间分布。对地层不同相的纵向和横向变化进行了定量评估；这包括分析近、中、远相的垂直和横向分布、河道充填沉积物的厚度和宽度、粒度变化以及流域内 19 个地点的漫滩与河道充填沉积物的比例。在各部分观察到的趋势表明大型风扇的升级。分布河流系统不同部分保存的相域各不相同。在近端，Lamurde、Tashan Alaji、Ture 和 Tula 的剖面仅显示向近端相的内侧传递。断面基部远侧湖相不存在。在 Hinna 系统的内侧部分，序列保留了向上传递到内侧相的远端。近、中、远相逐渐横向过渡，漫滩向上减少到河道充填沉积，河道充填厚度和宽度向上增加，都表明比马系统是一个进积分布的河流系统。分布河流系统不同部分保存的相域各不相同。在近端，Lamurde、Tashan Alaji、Ture 和 Tula 的剖面仅显示向近端相的内侧传递。断面基部远侧湖相不存在。在 Hinna 系统的内侧部分，序列保留了向上传递到内侧相的远端。近、中、远相逐渐横向过渡，漫滩向上减少到河道充填沉积，河道充填厚度和宽度向上增加，都表明比马系统是一个进积分布的河流系统。分布河流系统不同部分保存的相域各不相同。在近端，Lamurde、Tashan Alaji、Ture 和 Tula 的剖面仅显示向近端相的内侧传递。断面基部远侧湖相不存在。在 Hinna 系统的内侧部分，序列保留了向上传递到内侧相的远端。由近、中、远相逐渐横向过渡，漫滩向上减少到河道充填沉积，河道充填厚度和宽度向上增加，都表明比马系统是一个进积分布的河流系统。断面基部远侧湖相不存在。在 Hinna 系统的内侧部分，序列保留了向上传递到内侧相的远端。近、中、远相逐渐横向过渡，漫滩向上减少到河道充填沉积，河道充填厚度和宽度向上增加，都表明比马系统是一个进积分布的河流系统。断面基部远侧湖相不存在。在 Hinna 系统的内侧部分，序列保留了向上传递到内侧相的远端。由近、中、远相逐渐横向过渡，漫滩向上减少到河道充填沉积，河道充填厚度和宽度向上增加，都表明比马系统是一个进积分布的河流系统。