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

纳米比亚西北部骨架海岸扇系统分析混合泥石流/辫状河主导扇的特征和梯度约束

基本信息

批准号：
27665396
负责人：
Professor Dr. Harald Stollhofen
金额：
--
依托单位：
GeoZentrum Nordbayern
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2006
资助国家：
德国
起止时间：
2005-12-31 至 2010-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/27665396?language=en
关键词：
Characterisation gradient constraint mixed debris

项目摘要

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.

关于空中风扇的分类以及它们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)以低曲度/曲流河为主的末端成员的一系列地面扇的观点在科学界得到了相当大的接受。另一方面，认为这一频谱还不完全发育，大型低坡度河漫滩与小型高坡度冲积扇之间存在明显的水力特性和沉积坡度的天然鸿沟。后一种分类将把冲积扇限制为以泥石流为主的类型，并排除以河流为主的扇。纳米比亚西北部骨架海岸的冲积扇系统，即Sout、Salt、Messum和Horingbaai扇，可能在辫状河为主的扇系统和泥石流为主的扇系统之间架起一座桥梁。通过综合地形测绘、激光测量、卫星和航空摄影图像以及SRTM数据，对这些风扇的几何形状、排水网络和水道限制的控制进行分析，以开发风扇表面的3D数字模型。现代和古代扇序列中岩相组合的测井和测年、古水流指标的定向测量以及沉积物的结构和成分特征的分析，旨在了解沉积过程的性质和原因、活动的年龄和持续时间、现代过程历史和古代相序。因此，该项目将在很大程度上支持对与扇系统有关的沉积过程的控制的理解，并有助于综合分类。此外，需要将这些扇子与古代的等价物进行比较，以确定它们在摇滚唱片中的重要性。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。