Arid
DOI10.1111/sed.12387
Sedimentary processes controlling ultralong cells of littoral transport: Placer formation and termination of the Orange sand highway in southern Angola
Garzanti, Eduardo1; Dinis, Pedro2; Vermeesch, Pieter3; Ando, Sergio1; Hahn, Annette4; Huvi, Joao5; Limonta, Mara1; Padoan, Marta1; Resentini, Alberto1; Rittner, Martin3; Vezzoli, Giovanni1
通讯作者Garzanti, Eduardo
来源期刊SEDIMENTOLOGY
ISSN0037-0746
EISSN1365-3091
出版年2018
卷号65期号:2页码:431-460
英文摘要

This study focuses on the causes, modalities and obstacles of sediment transfer in the longest cell of littoral sand drift documented on Earth so far. Sand derived from the Orange River is dragged by swell waves and persistent southerly winds to accumulate in four successive dunefields in coastal Namibia to Angola. All four dunefields are terminated by river valleys, where aeolian sand is flushed back to the ocean; and yet sediment transport continues at sea, tracing an 1800km long submarine sand highway. Sand drift would extend northward to beyond the Congo if the shelf did not become progressively narrower in southern Angola, where drifting sand is funnelled towards oceanic depths via canyon heads connected to river mouths. Garnet-magnetite placers are widespread along this coastal stretch, indicating systematic loss of the low-density feldspatho-quartzose fraction to the deep ocean. More than half of Mocamedes Desert sand is derived from the Orange River, and the rest in similar proportions from the Cunene River and from the Swakop and other rivers draining the Damara Orogen in Namibia. The Orange fingerprint, characterized by basaltic rock fragments, clinopyroxene grains and bimodal zircon-age spectra with peaks at ca 05Ga and ca 10Ga, is lost abruptly at Namibe, and beach sands further north have abundant feldspar, amphibole-epidote suites and unimodal zircon-age spectra with a peak at ca 20Ga, documenting local provenance from Palaeoproterozoic basement. Along with this oblique-rifted continental margin, beach placers are dominated by Fe-Ti-Cr oxides with more monazite than garnet and thus have a geochemical signature sharply different from beach placers found all the way along the Orange littoral cell. High-resolution mineralogical studies allow us to trace sediment dispersal over distances of thousands of kilometres, providing essential information for the correct reconstruction of source to sink’ relationships in hydrocarbon exploration and to predict the long-term impact of man-made infrastructures on coastal sediment budgets.


英文关键词Detrital-zircon geochronology garnet and pyroxene chemistry grain density and geochemistry of placer deposits heavy minerals longshore sediment transport Mocamedes Desert and Cunene River sands Raman counting of deep-sea silt sedimentary petrology
类型Review
语种英语
国家Italy ; Portugal ; England ; Germany ; Angola
收录类别SCI-E
WOS记录号WOS:000419514900004
WOS关键词TSONDAB SANDSTONE FORMATION ; GRAIN-SIZE ; CONTINENTAL-MARGIN ; SKELETON COAST ; NAMIB DESERT ; RIVER ; SYSTEM ; SEA ; PROVENANCE ; DEPOSITS
WOS类目Geology
WOS研究方向Geology
来源机构University of London
资源类型期刊论文
条目标识符http://119.78.100.177/qdio/handle/2XILL650/213129
作者单位1.Univ Milano Bicocca, Dept Earth & Environm Sci, Lab Provenance Studies, I-20126 Milan, Italy;
2.Univ Coimbra, MARE Marine & Environm Sci Ctr, Dept Earth Sci, P-3004517 Largo Marques De Pombal, Portugal;
3.UCL, Dept Earth Sci, London Geochronol Ctr, London WC1E 6BT, England;
4.Univ Bremen, MARUM Ctr Marine Environm Sci, Leobener Str 8, D-28359 Bremen, Germany;
5.Univ Katyavala Bwila, Marine & Environm Sci Ctr, Rua Jose Falcao 67, Benguela 1725, Angola
推荐引用方式
GB/T 7714
Garzanti, Eduardo,Dinis, Pedro,Vermeesch, Pieter,et al. Sedimentary processes controlling ultralong cells of littoral transport: Placer formation and termination of the Orange sand highway in southern Angola[J]. University of London,2018,65(2):431-460.
APA Garzanti, Eduardo.,Dinis, Pedro.,Vermeesch, Pieter.,Ando, Sergio.,Hahn, Annette.,...&Vezzoli, Giovanni.(2018).Sedimentary processes controlling ultralong cells of littoral transport: Placer formation and termination of the Orange sand highway in southern Angola.SEDIMENTOLOGY,65(2),431-460.
MLA Garzanti, Eduardo,et al."Sedimentary processes controlling ultralong cells of littoral transport: Placer formation and termination of the Orange sand highway in southern Angola".SEDIMENTOLOGY 65.2(2018):431-460.
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