Fluvial-Aeolian Sedimentary Facies, Sossusvlei, Namib Desert
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Journal of Maps ISSN: (Print) 1744-5647 (Online) Journal homepage: https://www.tandfonline.com/loi/tjom20 Fluvial-aeolian sedimentary facies, Sossusvlei, Namib Desert Amelie Feder, Robert Zimmermann, Harald Stollhofen, Luca Caracciolo, Eduardo Garzanti & Louis Andreani To cite this article: Amelie Feder, Robert Zimmermann, Harald Stollhofen, Luca Caracciolo, Eduardo Garzanti & Louis Andreani (2018) Fluvial-aeolian sedimentary facies, Sossusvlei, Namib Desert, Journal of Maps, 14:2, 630-643, DOI: 10.1080/17445647.2018.1526719 To link to this article: https://doi.org/10.1080/17445647.2018.1526719 © 2018 The Author(s). Published by Informa View supplementary material UK Limited, trading as Taylor & Francis Group on behalf of Journal of Maps Published online: 18 Oct 2018. Submit your article to this journal Article views: 1271 View related articles View Crossmark data Citing articles: 1 View citing articles Full Terms & Conditions of access and use can be found at https://www.tandfonline.com/action/journalInformation?journalCode=tjom20 JOURNAL OF MAPS 2018, VOL. 14, NO. 2, 630–643 https://doi.org/10.1080/17445647.2018.1526719 Science Fluvial-aeolian sedimentary facies, Sossusvlei, Namib Desert Amelie Federa, Robert Zimmermann b, Harald Stollhofen a, Luca Caracciolo a, Eduardo Garzanti c and Louis Andreani b aGeoZentrum Nordbayern, Friedrich-Alexander-University (FAU) Erlangen-Nürnberg, Erlangen, Germany; bDivision ‘Exploration Technology’, Helmholtz-Zentrum Dresden-Rossendorf, Helmholtz Institute Freiberg for Resource Technology, Freiberg, Germany; cLaboratory for Provenance Studies, Department of Earth and Environmental Sciences, University of Milano-Bicocca, Milano, Italy ABSTRACT ARTICLE HISTORY Aeolian sedimentary processes and corresponding facies shape the Earth’s surface and control Received 17 April 2018 the evolution of dune fields. The Namib Sand Sea with its Sossusvlei playa-lake is a perfect Revised 10 September 2018 example to investigate the spatial distribution of fluvially influenced aeolian deposits. Accepted 11 September 2018 Remote sensing in combination with ground observations allowed for mapping of the facies fl KEYWORDS distribution pattern of associated uvial and aeolian sediments. Laboratory spectral signature Sossus sand formation; world measurements were used to further improve the separation between six groups of facies: view 3; dune river interaction; modern aeolian sand, deflation surface, mud pool/mud drapes, heavy mineral lag, reworked modern sediments; facies fluvial–aeolian sediments, and fossil dune remnant. The best results were achieved through a mapping; Quaternary supervised classification algorithm trained by field observations, a combination of Principal Component Analysis, band ratios, texture and geomorphologic indices. Consequently, a map outlining the facies distribution pattern of the Sossusvlei area at a scale of 1:10,000 was created. We propose this as a possible workflow to efficiently map and monitor desert environments and to investigate the interplay of aeolian and fluvial sediments. 1. Introduction Remote sensing is a valuable tool for lithological map- thickness of the sand (Blumberg, 2006; Bullard, ping of remote or inaccessible areas. In the last decade, White, & Livingstone, 2011a; Lancaster, 1989)and it has been successfully applied for mineral mapping the distribution of dune types, which have been and exploration of different terrains using various sen- mapped extensively (Besler, 1980; Breed et al., 1979; sor combinations (Bertoldi et al., 2011; Bullard, White, Livingstone et al., 2010). However, a detailed map & Livingstone, 2011b; Sabins, 1999; van der Meer et al., of sedimentological facies is still missing. Overall, 2012; Zimmermann, Brandmeier, Andreani, Mhopjeni, attempts to map the spatial distribution of sedimen- & Gloaguen, 2016). This technique has also been used tary facies with remote sensing are very scarce to investigate the geology and geomorphology of other (Castañeda, Herrero, & Casterad, 2005; Maeder planets, including Mars (Parker, Gorsline, Saunders, et al., 2002; Quintanar, Khan, Fathy, & Zalat, 2013; Pieri, & Schneeberger, 1993), Mercury (Stepinski, Raines, Offield, & Santos, 1978). This paper aims at Collier, McGovern, & Clifford, 2004) and Pluto (Telfer testing the applicability of remote sensing of facies et al., 2018). inasanddesertenvironment.Itisspecifically focused In the Namib Desert, numerous remote sensing at mapping and constraining the interaction between studies have been conducted over the last decades aeolian and ephemeral fluvial processes, as they are (Livingstone, 2013). Over this time, the technical pos- the main force for the generation of facies and the sibilities of remote sensing have improved and the geomorphological shaping. extracted information has increased in quality and In recent years, the topic of aeolian and fluvial inter- quantity. Strohbach (2008) created a catchment action in dryland environments has gained traction. map on the main rivers in Namibia with Shuttle The studies investigated controlling factors, different Radar Topography Mission-Digital Elevation Model interaction types and geomorphological landforms (SRTM-DEM) data and White, Walden, and Gurney (Al-Masrahy & Mountney, 2015; Bullard & Living- (2007) investigated changes in dune colour and iron stone, 2002; Liu & Coulthard, 2015; Roskin, Bookman, oxide content. The morphometry of dunes was Friesem, & Vardi, 2017). It is understood that fluvial– investigated focusing on their height, spacing and aeolian interaction is crucial for the evolution of CONTACT Amelie Feder [email protected] GeoZentrum Nordbayern, Friedrich-Alexander-University (FAU) Erlangen-Nürnberg, Erlangen, Germany Supplemental data for this article can be accessed at https://doi.org/10.1080/17445647.2018.1526719. © 2018 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group on behalf of Journal of Maps This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. JOURNAL OF MAPS 631 Figure 1. Location of the Namib Desert (shown in orange), the erg ‘Namib Sand Sea’ (shown in yellow) and the study area around Sossusvlei (modified after Livingstone, 2013) dune fields and that aeolian sediments may be mainly Data from the Worldview 3 platform are used preserved by fluvial interactions in inter-dune areas because of its high-spatial resolution as well as their (Fryberger, Krystinik, & Schenk, 1990). This paper band combination, making them particularly suitable focuses on the interplay of these two processes for geological analysis (Kruse, Baugh, & Perry, 2015; especially on the resulting facies and their spatial distri- Kruse & Perry, 2013; Ye, Tian, Ge, & Sun, 2017). bution and mixing of fluvial and aeolian sediments. This approach highlights compositional differences The Sossusvlei playa-lake system is located at the on an m-scale, with notably greater detail compared eastern flank of the Namib Sand Sea (sensu Lancaster, to other satellite systems (e.g. Advanced Spaceborne 1985) in central Namibia (Figure 1). It provides an Thermal Emission and Reflection Radiometer excellent example of sedimentological processes associ- (ASTER)). Such a high resolution is critical for sedi- ated with an ephemeral river repeatedly entering a mentological studies as they allow consideration of dune field, becoming dammed and finally terminating small-scale morphological features associated with in a flat inter-dune playa called ‘vlei’. The spectrum of sediment surfaces. aeolian and fluvial processes generates a complex inter- play of sedimentary facies, which make a facies map a 2. Namib Desert and Namib Sand Sea prerequisite to better understand the mutual relation- ships and distribution pattern of the sediments. The The Namib Sand Sea is part of the Namib Desert in Namib Sand Sea is perfectly suited for remote sensing central southern Namibia (Figure 1). It stretches as there is little vegetation, rare cloud coverage and from the ephemeral Kuiseb River in the north to restricted anthropogenic modification due to its setting Lüderitz in the south (Ward, 1988) and extends for in a protected national park area. up to 140 km inland (White et al., 2007). It contains 632 A. FEDER ET AL. a broad variety of different dune shapes: large linear length of 150 km, with a catchment area of about dunes, star-shaped dunes, simple and compound trans- 4000 km², and largely drains the Naukluft Mountains verse, barchanoid dunes, coppice dunes and sand- (Jacobson et al., 1995). The catchment comprises a var- ramps (Lancaster, 2014; Miller & Becker, 2008; Rowell iety of Neoproterozoic to Cambrian rocks, including et al., 2018; Stone, 2013). quartzite, shale, limestone, dolomite, porphyry, granite, Climatic conditions in the area have remained and gneiss (Villers et al., 1964). hyper arid since the Miocene (Lancaster, 2002). The The river flows across an extensive deflation plain convergence of the warm Angola Current with the and deeply penetrates the eastern flank of the sand cold Benguela Current and subtropical high-pressure sea for c. 40 km to terminate eventually at Sossusvlei. systems cause low humidity and only limited precipi- Water reaches the vlei only every few years (Brook, Sri- tation (ranging between ∼ <50 mm/yr at the coast to vastava, & Marais, 2006). Sparse vegetation grows ∼100 mm/yr near the