Characterisation and gradient constraint of mixed debris flow/braided river dominated fans by analysis of Skeleton Coast fan systems in NW Namibia

关于陆上扇的分类及其与河流的区别存在争议。一方面，包括（A）泥石流、（B）辫状河和（C）以低弯曲度/曲流河为主的端部成员的陆上扇谱的观点在科学界获得了相当大的认可。另一方面，它已被提出，这个频谱只是不完全的开发和一个明显的自然差距，水力特性和沉积坡度之间存在着大的低比降河流漫滩和小的高比降冲积扇。后者的分类将限制冲积扇泥石流为主的类型，并排除由河流为主的风扇。冲积扇系统，Sout，盐，Messum和Horingbaai风扇，骨架海岸，纳米比亚西北部，潜在的桥梁之间的差距辫状河为主，泥石流为主的风扇系统。将通过综合地形测绘、激光测量、卫星和航空照片图像以及SRTM数据，对这些扇体的几何形状、排水网络和通道限制控制进行分析，以开发扇体表面的三维数字模型。现代和古代扇序列中岩相组合的测井和定年、古水流指标的定向测量以及沉积物结构和成分特性的分析旨在了解沉积过程的性质和原因、活动的年龄和持续时间、近期过程历史和古代相序列。因此，该项目将在很大程度上支持对与扇系统相关的沉积过程的控制的理解，并有助于综合分类。此外，扇子需要与古代的对等物进行比较，以确定它们在岩石记录中的重要性。这一观点将有助于油气勘探中扇相的重新评价，特别是在目标生成方面。

There is a controversy concerning the classification of subaerial fans and their distinction from rivers. On one hand the view of a spectrum of subaerial fans comprising (A) debris flow, (B) braided river and (C) and low sinuosity/meandering river dominated end members has gained considerable acceptance in the scientific community. On the other hand it has been proposed that this spectrum is only incompletely developed and that an obvious natural gap in hydraulic character and depositional slope is existing between large low gradient river floodplains and small high gradient alluvial fans. The latter classification would restrict alluvial fans to debris flow dominated types and exclude fans dominated by rivers.Alluvial fan systems, the Sout, Salt, Messum and Horingbaai Fans, of the Skeleton Coast, northwestern Namibia, potentially bridge a gap between braided river dominated and debris flow dominated fan systems. These fans will be analysed in view of their geometries, drainage networks and controls of channel confinement by means of integrating terrain mapping, laser surveying, satellite and aerial photo imagery as well as SRTM data to develop 3D digital models of the fan surfaces. Logging and dating of lithofacies assemblages in modern and ancient fan successions, directional measurements of palaepurrent indicators and analysis of textural and compositional properties of sediments aim to understand nature and causes of depositional processes, age and duration of activity, recent process history and ancient facies sequences. The project will thus considerable support the understanding of controls on depositional processes associated with fan systems and contribute to an integrated classification. Furthermore, the fans need to be compared with ancient equivalents in order to establish their importance in the rock record. This point of view will contribute to the re-evaluation of fan facies in hydrocarbon exploration, specifically with respect to target generation.