DOI: 10.1016/j.quascirev.2015.07.011
Scopus记录号: 2-s2.0-84949317229
论文题名: The modern Nile sediment system: Processes and products
作者: Garzanti E. ; Andò S. ; Padoan M. ; Vezzoli G. ; El Kammar A.
刊名: Quaternary Science Reviews
ISSN: 2773791
出版年: 2015
卷: 130 起始页码: 9
结束页码: 56
语种: 英语
英文关键词: Anorogenic Volcanic provenance
; Continental block provenance
; Erosion rates and sediment budgets
; Geochemistry and chemical weathering
; Heavy minerals and hydraulic sorting
; Long-distance littoral transport
; Sediment mixing and recycling
; Sedimentary petrology and provenance models
Scopus关键词: Budget control
; Catchments
; Erosion
; Geochemistry
; Grain size and shape
; Igneous rocks
; Metamorphic rocks
; Minerals
; Mixing
; Petrography
; Recycling
; Rivers
; Sand
; Sedimentary rocks
; Sedimentology
; Titanium oxides
; Underwater mineralogy
; Volcanic rocks
; Volcanoes
; Weathering
; Anorogenic Volcanic provenance
; Chemical weathering
; Continental blocks
; Hydraulic sorting
; Long-distance littoral transport
; Provenance models
; Sediment budgets
; Sediments
英文摘要: We trace compositional changes of Nile sediments for 7400 km, from their sources in equatorial rift highlands of Burundi and Rwanda to their sink in the Mediterranean Sea. All chemical and physical controls on sediment petrography, mineralogy and geochemistry, including weathering, grain-size, hydraulic sorting, mechanical breakdown, anthropic impact, mixing and recycling are investigated in detail. The Nile course is controlled along its entire length by the East African-Red Sea Rift. In this anorogenic setting, detritus is derived in various proportions from volcanic fields associated with tectonic extension (Anorogenic Volcanic provenance) and from igneous, metamorphic and sedimentary rocks uplifted on the rift shoulders or exposed on the craton (Continental Block provenance). The entire spectrum of such detrital signatures is displayed in the Nile catchment. Volcaniclastic Atbara sand is generated by focused erosion of the Ethiopian basaltic plateau in semiarid climate, whereas quartzose White Nile sand reflects low erosion rates, extensive weathering and sediment trapping in lakes and swamps at equatorial to subequatorial latitudes. In the main Nile, as in its main tributary the Blue Nile, suspended load is volcaniclastic, whereas feldspatho-quartzose bedload is derived largely from basement sources, with fine to medium-grained eolian sand added along the lower course. Mixing of detrital populations with different provenance and grain size is reflected in diverse violations of settling-equivalence relationships in fluvial and deltaic sediments. Sediment delivery from Sudan has been cut off after closure of the Aswan High Dam and accelerated erosion of deltaic cusps is leading to local formation of placer lags dominated by ultradense Fe-Ti-Cr oxides, but mineralogical changes caused by man's radical modification of fluvial regimes have been minor so far. In beaches of Sinai, Gaza and Israel, the Nile volcaniclastic trace gets progressively diluted by quartzose sand recycled from eolian coastal deposits and carbonaticlastic detritus eroded from the Levant rift shoulder. Studying the compositional variability of modern sediments in big-river systems allows us to appreciate the richness of natural processes occurring in the vast drainage basin, and provides us with a key to understand the information stored in sedimentary archives and to reconstruct the evolution of the Earth's surface from the recent to the less recent past. © 2015 Elsevier Ltd. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/59755
Appears in Collections: 过去全球变化的重建
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作者单位: Laboratory for Provenance Studies, Department of Earth and Environmental Sciences, University of Milano-Bicocca, Milano, Italy; Geology Department, Cairo University, Giza, Egypt
Recommended Citation:
Garzanti E.,Andò S.,Padoan M.,et al. The modern Nile sediment system: Processes and products[J]. Quaternary Science Reviews,2015-01-01,130