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1
Rosales-Hoz, L., A. Carranza-Edwards, C. Mendez-Jaime, and M. A. Monreal-Gómez. "Metals in shelf sediments and their association with continental discharges in a tropical zone." Marine and Freshwater Research 50, no. 3 (1999): 189. http://dx.doi.org/10.1071/mf98107.
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Geochemical studies of shelf sediments of the south-eastern Gulf of Mexico were carried out to understand the influence of fluvial and fluvio–lagoonal discharges on sediment geochemistry and to study elemental distribution patterns that could be used together with hydrographic and sedimentological data to assess depth circulation. On the basis of sediment chemical composition, three provinces were identified: fluvial, fluvio–lagoonal and calcareous; their distribution is a function of circulation patterns and fluvio and fluvio–lagoonal discharges. Factor analysis separated the sediments into three groups: fluvial influence, anthropic activities and fluvio–lagoonal origin.
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Woronko, Barbara, Paweł Zieliński, and Robert Jan Sokołowski. "Climate evolution during the Pleniglacial and Late Glacial as recorded in quartz grain morphoscopy of fluvial to aeolian successions of the European Sand Belt." Geologos 21, no. 2 (June 1, 2015): 89–103. http://dx.doi.org/10.1515/logos-2015-0005.
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Abstract We present results of research into fluvial to aeolian successions at four sites in the foreland of the Last Glacial Maximum, i.e., the central part of the “European Sand Belt”. These sites include dune fields on higher-lying river terraces and alluvial fans. Sediments were subjected to detailed lithofacies analyses and sampling for morphoscopic assessment of quartz grains. Based on these results, three units were identified in the sedimentary succession: fluvial, fluvio-aeolian and aeolian. Material with traces of aeolian origin predominate in these sediments and this enabled conclusions on the activity of aeolian processes during the Pleniglacial and Late Glacial, and the source of sediment supply to be drawn. Aeolian processes played a major role in the deposition of the lower portions of the fluvial and fluvio-aeolian units. Aeolian material in the fluvial unit stems from aeolian accumulation of fluvial sediments within the valley as well as particles transported by wind from beyond the valley. The fluvio-aeolian unit is composed mainly of fluvial sediments that were subject to multiple redeposition, and long-term, intensive processing in an aeolian environment. In spite of the asynchronous onset of deposition of the fluvio-aeolian unit, it is characterised by the greatest homogeneity of structural and textural characteristics. Although the aeolian unit was laid down simultaneously, it is typified by the widest range of variation in quartz morphoscopic traits. It reflects local factors, mainly the origin of the source material, rather than climate. The duration of dune-formation processes was too short to be reflected in the morphoscopy of quartz grains.
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Marinho, Rogério Ribeiro, Antonio Fábio Sabbá Guimarães Vieira, and Feliciano De Souza Maciel. "Análise Montante-Jusante da Granulometria dos Sedimentos de Fundo e Suspenso do Rio Negro e Tributários (Bacia Amazônica, Brasil)." Revista Brasileira de Geografia Física 14, no. 2 (April 14, 2021): 997. http://dx.doi.org/10.26848/rbgf.v14.2.p997-1008.
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O conhecimento das características físicas de sedimentos transportados por grandes sistemas fluviais possui significativa importância para o entendimento de processos geomorfológicos e hidrológicos. O nível de conhecimento dos grandes sistemas fluviais da Amazônia e sua relação com o transporte de sedimentos ainda é limitado, resultando em lacunas de conhecimento sobre a dinâmica da paisagem nesta complexa região. Este trabalho teve como objetivo avaliar a distribuição espacial da granulometria de sedimentos de fundo e suspenso do Rio Negro e tributários. Realizou-se análise da distribuição do tamanho dos sedimentos em seções amostrais localizadas no alto, médio e baixo curso do Rio Negro. Os resultados da análise granulométrica da carga de fundo indicam a predominância de sedimentos com tamanho variando de 0,25 a 1,0 mm (principalmente areia fina, areia média e areia grossa) enquanto no baixo curso as amostram oscilaram de areia fina a partículas lamosas (< 0,50 mm). No Rio Negro os sedimentos suspensos são compostos principalmente de partículas finas de silte (90% menor que 80 µm) com diâmetro mediano (D50) de 25 µm. As características granulométricas apresentadas neste trabalho fornecem subsídios para o entendimento de processos hidrodinâmicos de transporte e deposição dos sedimentos de fundo e suspenso neste gigante sistema fluvial. Upstream-downstream Granulometry Analysis of bed and suspended sediments in the Negro River Basin (Amazon Basin, Brazil)A B S T R A C TThe knowledge of the physical characteristics of sediments transported by large river systems has significant importance for the understanding of geomorphological and hydrological processes. The level of knowledge of the large rivers of the Amazon basin and their relationship with sediment transport is limited, resulting in gaps about the dynamics of the landscape in this complex region. This article analyzes the spatial distribution of granulometry of bed and suspended sediments in the Negro River and tributaries. An analysis of the sediment size distribution was carried out in sample sections located in the upper, middle and lower reaches of the Negro River. The results of the granulometric analysis of the bed load indicate the predominance of sediments with sizes ranging from 0.25 to 1.0 mm (mainly fine sand, medium sand and coarse sand) while in the low course they showed oscillated from fine sand to muddy particles (<0.50 mm). In the Negro River basin the suspended sediments are composed mainly of fine silt particles (90% less than 80 µm) with a median diameter (D50) of 25 µm. The granulometric characteristics presented in this work provide subsidies for the understanding of hydrodynamic processes of transport and deposition of bed and suspended sediments in this huge fluvial system.Keywords: sediment transport, Amazon floodplain, multichannel river, anabranching
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Sawakuchi, André Oliveira, Vinicius Ribau Mendes, Fabiano do Nascimento Pupim, Thays Desiree Mineli, Ligia Maria Almeida Leite Ribeiro, Andre Zular, Carlos Conforti Ferreira Guedes, et al. "Optically stimulated luminescence and isothermal thermoluminescence dating of high sensitivity and well bleached quartz from Brazilian sediments: from Late Holocene to beyond the Quaternary?" Brazilian Journal of Geology 46, suppl 1 (June 2016): 209–26. http://dx.doi.org/10.1590/2317-488920160030295.
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ABSTRACT: The development of optically stimulated luminescence (OSL) dating of sediments has led to considerable advance in the geochronology of the Quaternary. OSL dating is a well established technique to determine sediment burial ages from tens of years to few hundred thousand years. Recent studies have shown that Quaternary sediments of Brazil are dominated by quartz grains with high luminescence sensitivity, allowing the determination of precise and reliable OSL burial ages. In this paper, we show examples of OSL dating of quartz aliquots and single grains from different regions in Brazil, including young coastal-eolian Late Holocene (< 100 years) to Late Pleistocene (~ 150 ka) fluvial sediments. We discuss the OSL data and ages of sediments from carbonate and terrigenous (distributary and tributary systems) fluvial depositional contexts in Brazil. Most of the studied fluvial sediments show equivalent dose distributions with low to moderate dispersion, suggesting well bleached sediments. The comparison between aliquot and single grain data suggests that high overdispersion in equivalent dose distributions of some samples is more related with sediment mixture due to bioturbation than with incomplete bleaching during transport. Well bleached fluvial sediments contrast with the poor bleached pattern usually described for fluvial sediments in the literature. A large part of the fluvial sedimentary record in Brazil is older than the age limit for quartz OSL dating using blue light stimulation. Thus, isothermal thermoluminescence (ITL) dating protocols were tested for dating of fluvial sands from the Xingu River (eastern Amazonia). The studied sample can recover reliable equivalent doses up to 1600 Gy using the ITL 310oC signal. Therefore, this signal would be suitable to extend the age limit of quartz luminescence to the whole Quaternary or beyond (> 2 Ma) in the low dose rate (0.5 - 1.0 Gy/ka) environments typical for Brazilian sediments.
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Wang, H., and X. Jia. "Selective deposition response to aeolian-fluvial sediment supply in the desert braided channel of the Upper Yellow River, China." Natural Hazards and Earth System Sciences Discussions 3, no. 2 (February 10, 2015): 1269–90. http://dx.doi.org/10.5194/nhessd-3-1269-2015.
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Abstract. Rivers flow across aeolian dunes and develop braided stream channels. Both aeolian and fluvial sediment supplies regulate sediment transport and deposition in such a cross-dune braided river. Here we show a significant selective deposition in response to both aeolian and fluvial sediment supplies in the Ulan Buh desert braided channel. This selective deposition developed by the interaction between the flows and the Aeolian-fluvial sediment supplies, making the coarser sediments (> 0.08 mm) from aeolian sand supply and bank erosion to accumulate in the channel center and the finer fluvial sediments (< 0.08 mm) to be deposited on the bar and floodplain surfaces and forming a coarser-grained thalweg bed bounded by finer-grained floodplain surfaces. This lateral selective deposition reduces the downstream sediment transport and is a primary reason for the formation of "above-ground river" in the braided reach of the Upper Yellow River in response to aeolian and fluvial sediment supplies.
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Wang, H., X. Jia, Y. Li, and W. Peng. "Selective deposition response to aeolian–fluvial sediment supply in the desert braided channel of the upper Yellow River, China." Natural Hazards and Earth System Sciences 15, no. 9 (September 2, 2015): 1955–62. http://dx.doi.org/10.5194/nhess-15-1955-2015.
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Abstract. Rivers flow across aeolian dunes and develop braided stream channels. Both aeolian and fluvial sediment supplies regulate sediment transport and deposition in such cross-dune braided rivers. Here we show a significant selective deposition in response to both aeolian and fluvial sediment supplies in the Ulan Buh desert braided channel. The Ulan Buh desert is the main coarse sediment source for this desert braided channel, and the mean percentage of the coarser (> 0.08 mm) grains on the aeolian dunes surface is 95.34 %. The lateral selective deposition process is developed by the interaction between the flows and the aeolian–fluvial sediment supplies, causing the coarser sediments (> 0.08 mm) from aeolian sand supply and bank erosion to accumulate in the channel centre and the finer fluvial sediments (< 0.08 mm) to be deposited on the bar and floodplain surfaces, forming a coarser-grained thalweg bed bounded by finer-grained floodplain surfaces. This lateral selective deposition reduces the downstream sediment transport and is a primary reason for the formation of an "above-ground" river in the braided reach of the upper Yellow River in response to aeolian and fluvial sediment supplies.
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Halifa-Marín, A., P. Pérez-Cutillas, M. Almagro, and C. Boix-Fayos. "Presión antrópica sobre cuencas de drenaje en ecosistemas frágiles: variaciones en las existencias (stock) de carbono orgánico asociadas a cambios morfológicos fluviales." Cuadernos de Investigación Geográfica 45, no. 1 (June 18, 2019): 245. http://dx.doi.org/10.18172/cig.3690.
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Anthropic changes in the drainage area of catchments can influence dominant erosion processes and sediment sources and mobilize specific carbon pools. It also causes changes in the sedimentary dynamics and thus in the fluvial morphology. At the same time fluvial morphologies can create the conditions for stabilizing organic carbon (OC) in sediments by burial, carbon preservation, slowing down mineralization processes, and terrestrial or aquatic plant colonization. All this might have a significant impact on the fluvial carbon sink or sources. This work explores the impact of changes in the drainage area (reforestation, check-dam building, agricultural abandonment) on fluvial morphology and on the sedimentary carbon sink of an arid and erodible catchment. The methodological approach combines cartographic analysis of land use, geomorphological photointerpretation of the channel and slope-channel connections in 1956 and 2016. Furthermore, soil and sediment sampling across the catchment for organic carbon stock determination was carried out. The watershed underwent a drastic transformation of land use from 1956, changing from an agrarian scenario to a forest pattern in 2016. This evolution altered sedimentological dynamics and fluvial morphologies. The active channel was narrowed (52%) whereas bank erosion (77%) and the adjacent gullies (11%) increased. The inner alluvial plain increased up to 31% and alluvial fans up to 37%. In addition, vegetation in the channel increased up to 16%. All this led to an increase of the total OC pool of fluvial sediments (12%), slightly above than the increase of OC total pool in the soils of the catchment (10%). The ratio of the OC stock sediments/soils was > 0.8, which indicates the large capacity of carbon sequestration of fluvial sediments, with OC stocks larger than those of agricultural soils. It was found that the geomorphological dynamics plays an important role in the OC fluvial flows. In scenarios of channel narrowing and vegetation encroachment of fluvial morphologies, the sediments can stabilize and generate OC sinks. These processes of OC sequestration in dry and ephemeral channels can have a large relevance for various ecosystem services and should be considered in the management of fluvial sedimentary areas.
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Galia, Tomáš, and Václav Škarpich. "Coarse Bed Sediments in a Headwater Channel as Indicators of Fluvial Processes and Slope-Channel Coupling: A Case Study from the Carpathian Mountains (Czech Republic)." Moravian Geographical Reports 21, no. 3 (September 1, 2013): 2–11. http://dx.doi.org/10.2478/mgr-2013-0012.
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Abstract The character of riverbed sediments usually reflects fluvial processes and the dynamics of sediment transport in fluvial systems. The approach in this study was based on the measurement of the largest boulders located within a bankfull channel, and on the observation of changes in their size in the longitudinal profile of a headwater stream in the Moravian-Silesian Beskids Mountains. The resulting trends in a particle-size index reflect the character of sediment delivery into channel segments and the recent channel-forming processes. The largest boulders were observed in channel sections with a strong interaction of slope and fluvial processes, and a slight coarsening of sediments was recorded in the incised downstream sections of the longitudinal stream profile. In contrast, the refining of bed sediments was typical of the transitional zone between slope-channel coupled reaches and an alluvial cone characterised by a tendency to material aggradation.
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Aleixo, Yan De Mello, Márcio Henrique De Campos Zancopé, and Luis Felipe Soares Cherem. "O Papel do Perfil Longitudinal na atenuação do Potencial de Transporte de Sedimentos em Bacias Hidrográficas: o caso do Parque Estadual de Terra Ronca (GO), Brasil." Revista Brasileira de Geografia Física 12, no. 5 (June 28, 2019): 1730. http://dx.doi.org/10.26848/rbgf.v12.5.p1730-1745.
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A forma dos perfis longitudinais dos cursos d’água associada à distribuição das planícies aluviais adjacentes permitem identificar trechos com predomínio de processos agradacionais e denudacionais nos sistemas fluviais. Este trabalho identifica trechos dos perfis longitudinais dos rios a montante do Parque Estadual de Terra Ronca, no nordeste do estado de Goiás, que possuem tendências diferentes para transferência de sedimentos para jusante. Os rios cujos perfis longitudinais mais atenuam o potencial de transferência de sedimentos são: o São Vicente, da Lapa e Angélica. A forma dos perfis e a distribuição das planícies aluviais estão intrinsecamente ligados aos compartimentos geomorfológicos da área do Parque Estadual de Terra Ronca e à evolução do relevo regional, influenciando o transporte de sedimentos da rede de drenagem.The Role of the Longitudinal Profile in the attenuation of the Potential of Transport of Sediments in Watersheds: the case of the Terra Ronca State Park (GO), Brazil A B S T R A C TThe shape of the longitudinal profiles of rivers associated with the distribution of the adjacent floodplains allows identifying sections with predominance of aggradational and denudational processes in the fluvial systems. This paper identifies stretches of the longitudinal profiles of the rivers upstream of the Terra Ronca State Park, in the northeast of the state of Goiás, which have different trends to transfer of sediments to downstream. The rivers whose longitudinal profiles more attenuate the sediment transfer potential are: São Vicente, Lapa and Angélica. The shape of the profiles and the distribution of alluvial plains are intrinsically linked to the geomorphological compartments of the Terra Ronca State Park’s area and the evolution of the regional relief, influencing the sediment transportation of the fluvial drainage network.Keywords: sediment transportation, alluvial plains, geomorphological compartmentation.
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Retelle, Michael J. "Stratigraphy and Sedimentology of Coastal Lacustrine Basins, Northeastern Ellesmere Island, N. W. T." Géographie physique et Quaternaire 40, no. 2 (December 4, 2007): 117–28. http://dx.doi.org/10.7202/032632ar.
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ABSTRACT Sediment cores recovered from three high arctic coastal lake basins contain a sequence of glaciomarine sediments overlain by laminated to massive-bedded lacustrine sediments. Glaciomarine sediments were deposited while the basins were isostatically depressed below sea level. Subsequent to emergence of the basin from the sea, lacustrine sediments accumulated in each basin. A transitional fades between the marine and lacustrine units represents an isolation interval during which trapped sea water lay beneath a freshwater lens. Sedimentological and faunal evidence from sediment cores demonstrates that embayments were closed and fluvial sedimentation was minimal during the glacial maximum (ca. 8000-8200 BP) Subsequent increases in sand content and macrofaunal abundance reflects increases in mobility of sea ice and fluvial input during the middle Holocene. Late HoIocene cooling trends are demonstrated by decreases in ice rafted material and an increase in diffuse bedding in lake surface sediments.
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de Jalón, Diego García, Martina Bussettini, Massimo Rinaldi, Gordon Grant, Nikolai Friberg, Ian G. Cowx, Fernando Magdaleno, and Tom Buijse. "Linking environmental flows to sediment dynamics." Water Policy 19, no. 2 (December 5, 2016): 358–75. http://dx.doi.org/10.2166/wp.2016.106.
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This is a policy discussion paper aimed at addressing possible alternative approaches for environmental flows (e-Flows) assessment and identification within the context of best strategies for fluvial restoration. We focus on dammed rivers in Mediterranean regions. Fluvial species and their ecological integrity are the result of their evolutionary adaptation to river habitats. Flowing water is the main driver for development and maintenance of these habitats, which is why e-Flows are needed where societal demands are depleting water resources. Fluvial habitats are also shaped by the combined interaction of water, sediments, woody/organic material, and riparian vegetation. Water abstraction, flow regulation by dams, gravel pits or siltation by fine sediments eroded from hillslopes are pressures that can disturb interactions among water, sediments, and other constituents that create the habitats needed by fluvial communities. Present e-Flow design criteria are based only on water flow requirements. Here we argue that sediment dynamics need to be considered when specifying instream flows, thereby expanding the environmental objectives and definition of e-Flows to include sediments (extended e-Flows). To this aim, a hydromorphological framework for e-Flows assessment and identification of best strategies for fluvial restoration, including the context of rivers regulated by large dams, is presented.
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Adiotomre, Emmanuel E., Innocent O. Ejeh, and Edwin O. Adaikpoh. "Geochemistry of Fluvial Sediments from Geregu, Southwest Nigeria." Materials and Geoenvironment 64, no. 1 (March 24, 2017): 35–52. http://dx.doi.org/10.1515/rmzmag-2017-0004.
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Abstract Geochemical analysis of fluvial sediments on the banks of River Ero using inductively coupled plasma mass spectrometry illustrates their maturity, provenance and tectonic setting. The analysed sediment samples show low SiO2/Al2O3 ratios of 2.92-2.99 (units FL_A, FL_B and FL_E) and high SiO2/Al2O3 ratios of 4.064-4.852 (units FL_C, FL_D, FL_F and FL_G). Sediments were geochemically classified as shales (units FL_A, FL_B and FL_E) and greywackes (units FL_C, FL_D, FL_F and FL_G). Variability in sediment maturity (FL_F > FL_G >FL_C >FL_D >FL_A > FL_B > FL_E) parallels a decreasing order in the ratios of SiO2/Al2O3 and K2O/Al2O3, as well as the proportion of quartz grains and matrix components. Evidence from Al2O3/TiO2, K2O, Rb, La/Co, Th/Co, Cr/ Th, Th/Cr, La/Th-Hf, Th-Hf-Co and rare earth element contents of sediment samples suggest felsic protoliths of upper continental crust in a passive margin tectonic setting. An insignificant contribution of mafic components from the source is, however, inferred based on the Ni and Cr contents of the sediment samples. Combined Eu anomalies <0.85 and (Gd/Yb)n ratios <2.0 (1.53- 1.82, average 1.65) suggest post-Archean protoliths.
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Marren, Philip M. "Sedimentology of proglacial rivers in eastern Scotland during the Late Devensian." Transactions of the Royal Society of Edinburgh: Earth Sciences 92, no. 2 (June 2001): 149–71. http://dx.doi.org/10.1017/s0263593300000110.
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ABSTRACTThis paper reconstructs the characteristics of rivers which deposited proglacial fluvial sediments in east-central Scotland during the Late Devensian. Sediment depositional architecture and geometry, together with the relationship between high-stage and falling and low-stage depositional elements, were used to relate the proglacial sediments to the glacial meltwater discharge regime. The proglacial river systems studied were dominated by ‘normal’ ablation controlled discharge, rather than by high magnitude flood events. Consequently there is a great deal of spatial and vertical variability. Deposition occurred during short intervals of rapid aggradation, so that relatively fine-grained falling-stage sediments, as well as coarser, bar-core sediments are well preserved. Models relating the characteristics of the final deposit to the nature of the river are presented. These emphasise the role of stage changes and aggradation rates in controlling sediment architecture in braided fluvial deposits.
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Bomer, Edwin J., Carol A. Wilson, and Dilip K. Datta. "An Integrated Approach for Constraining Depositional Zones in a Tide-Influenced River: Insights from the Gorai River, Southwest Bangladesh." Water 11, no. 10 (September 30, 2019): 2047. http://dx.doi.org/10.3390/w11102047.
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The tidal to fluvial transition (TFT) of estuaries and coastal rivers is one of the most complex environments on Earth with respect to the transportation and deposition of sediment, owing in large part to competing fluvial and marine processes. While there have been recent advances in the stratigraphic understanding of the TFT, it is still unclear whether these findings are site-specific or representative of mixed tidal-fluvial systems worldwide. Yet, research from this depositional domain holds profound societal and economic importance. For instance, understanding the underlying stratigraphic architecture of channel margins is critical for assessing geomorphic change for fluvio-deltaic settings, which are generally vulnerable to lateral channel migration and resultant erosion. Findings would also benefit paleo-geographic reconstructions of ancient tide-influenced successions and provide an analog for hydrocarbon reservoir models. In the Ganges-Brahmaputra Delta of Bangladesh, the Gorai River is one of two Ganges distributaries actively connected to the Bay of Bengal. With fluvial input from the Ganges and meso-scale (2–4 m range) tides at the coast, the Gorai exhibits a variety of hydrodynamic regimes across its 350-km reach, providing a unique opportunity to investigate along-channel depositional patterns across the TFT. This study integrates multiple datasets—core sedimentology, river channel bathymetry, and remote sensing—to provide a process-based framework for determining the relative position of sedimentary deposits within the tidal-fluvial continuum of the Gorai River. The results of this investigation reveal coincident, abrupt shifts in river channel morphology and sediment character, suggesting the occurrence of backwater-induced mass extraction of relatively coarse sediments (i.e., fine sand). Despite being situated in an energetic tidal environment, evidence of tidal cyclicity in cored sediments is relatively rare, and the bulk stratigraphy appears strongly overprinted by irregularly spaced cm- to dm-scale sediment packages, likely derived from monsoonal flood pulses. Such findings differ from previously-studied mixed tidal-fluvial systems and underscore the site-specific complexities associated with this depositional domain.
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Li, Fuqiang, Baotian Pan, Zhongping Lai, Hongshan Gao, and Xianjiao Ou. "Identifying the degree of luminescence signal bleaching in fluvial sediments from the Inner Mongolian reaches of the Yellow River." Geochronometria 45, no. 1 (April 10, 2018): 82–96. http://dx.doi.org/10.1515/geochr-2015-0087.
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Abstract The partial bleaching of the luminescence signal prior to deposition results in age overestimation, and can be a problem in delineating fluvial evolution within an OSL chronological framework. The Inner Mongolian reaches of the Yellow River are characterised by a high sediment load and complex sources of sediments. To test the incomplete bleaching occurring in this type of environment, the residual doses and the luminescence signal characteristics of different particle size fractions from 14 modern fluvial sediment samples were investigated. Furthermore, 26 OSL ages derived from drilling cores were compared with 11 radiocarbon ages. Our results show that the residual equivalent doses principally range between 0.16 and 0.49 Gy for silt grains, and between 0.35 and 3.72 Gy for sand grains of modern samples. This suggests that medium-grained quartz has been well bleached prior to deposition, and is preferable to coarse-grained quartz when dating fluvial sediments in this region. The results also show that the De values of coarse-grained fractions display a stronger correlation with distance downstream. In addition, a comparison of OSL and radiocarbon ages from drilling cores establishes further confidence that any initial bleaching of these sediments was sufficient. As a result, we believe that the studied fluvial samples were well bleached prior to deposition.
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Pailles, C., and PW Moody. "Phosphorus sorption-desorption by some sediments of the Johnstone Rivers catchment, northern Queensland." Marine and Freshwater Research 43, no. 6 (1992): 1535. http://dx.doi.org/10.1071/mf9921535.
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Phosphorus (P) sorption-desorption characteristics were determined for 11 sediments from the Johnstone Rivers catchment, northern Queensland. Sediments were selected to cover a range in values of Bray extractable P from 0.1 to 10.4 mg P kg-1. P sorption curves were determined by using 0.01 M NaCl to simulate fluvial water conditions and, on a restricted number of sediments, 0.5 M NaCl to simulate sea water. The amounts of P released in 10 successive extractions for 30 min with 0.01 M CaCl2 were determined for each sediment. The amounts of P desorbed either declined to nondetectable levels or declined to a constant amount. These desorption curves were used to delineate 'rapidly desorbable' P from 'slowly desorbable' P. Bray extractable P and adsorption characteristics (equilibrium solution P concentration and P buffer capacity) were poorly correlated with 'rapidly desorbable' P. Most sediments in the suite would act as P sinks in both fluvial and marine environments because their equilibrium P concentrations are lower than the dissolved inorganic P concentrations of their respective water columns. For those sediments acting as potential sources (5 from 11 in 0.01 M NaC1, 2 from 6 in 0.5 M NaCl), amounts of P that could potentially be desorbed into the fluvial water column ranged from 0.1 to 3.9 mg P kg-1 sediment.
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Sidorchuk, A. Yu. "THE FLUVIAL SYSTEM ON THE EAST EUROPEAN PLAIN: SEDIMENT SOURCE AND SINk." GEOGRAPHY, ENVIRONMENT, SUSTAINABILITY 11, no. 3 (September 29, 2018): 5–20. http://dx.doi.org/10.24057/2071-9388-2018-11-3-05-20.
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The modern fluvial system on the lowland East European Plain is of depositional type. Sediment transport to the seas is only a few percent of the total erosion, and the main part of eroded material is accumulated in the channels. The recent deposition of suspended sediments is caused by accelerated soil erosion on the arable slopes, which led to a high rate of lateral sediment input and deposition at the river headwaters and on the floodplains. The process of accumulation is facilitated by the unfilled “negative” volume of the net of dry valleys formed during the Late Glacial catastrophic erosion event. Such events of catastrophic erosion of the sediments deposited in the lowland fluvial systems occur with a frequency of 100-120 thousand years. In the conditions of both scarce vegetation and extremal surface runoff, the entire fluvial systems become the area of intensive erosion, with the deep incision of gullies and of the river channels. Therefore, despite the modern intensive deposition, delivery ratio for the fluvial systems on this lowland territory is close to one in the long-term perspective.
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Personius, Stephen F., Harvey M. Kelsey, and Paul C. Grabau. "Evidence for Regional Stream Aggradation in the Central Oregon Coast Range during the Pleistocene-Holocene Transition." Quaternary Research 40, no. 3 (November 1993): 297–308. http://dx.doi.org/10.1006/qres.1993.1083.
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AbstractLow, nearly continuous terraces of similar age are present along streams in drainage basins that range in size from Drift Creek (190 km2) to the Umpqua River (11,800 km2) in the Oregon Coast Range. Radiocarbon ages from near the bose of fluvial sediments underlying these terraces are clustered at about 9000-11,000 14C yr B.P. Beveled bedrock surfaces (straths) that underlie the fluvial sediments are 1-8 m above summer stream levels and are present along most of the nontidal reaches of the rivers that we studied. Where exposed, the bedrock straths are overlain by 2-11 m of fluvial sediment that consists of a bottom-stratum (channel) facies of sandy pebble-cobble gravel and a top-stratum (overbank) facies of sandy silt or silt. Eight radiocarbon ages from the fluvial sediments allow correlation of the lowest continuous terrace over a wide area and thus indicate that a regional aggradation episode occurred in Coast Range drainage basins during the Pleistocene-Holocene transition. The cause of such widespread aggradation is unknown but may be related to climate-induced changes in the frequency of evacuation of colluvium from hollows, which are common in all drainage basins in the region.
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Hein, Frances J., James P. M. Syvitski, Lynda A. Dredge, and Bernard F. Long. "Quaternary sedimentation and marine placers along the North Shore, Gulf of St. Lawrence." Canadian Journal of Earth Sciences 30, no. 3 (March 1, 1993): 553–74. http://dx.doi.org/10.1139/e93-043.
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Offshore areas, along the North Shore of the St. Lawrence Estuary, have major lithostratigraphic and seismostratigraphic units that relate to the advance or retreat of the Late Wisconsinan Ice Sheet, subsequent marine transgression or regression, and reworking of postglacial deposits. Glacial diamicton and glaciomarine units (acoustic units 1 and 2) were emplaced between >18 and 14.5 ka, by basal meltout or ice-marginal sedimentation; they reflect ice-proximal sedimentation associated with ice-terminal stillstands. Deep-water muds (acoustic unit 3) represent ice-distal accumulation of glaciomarine sediment from glaciofluvial plumes between 13.5 and 11 ka. After this time exceptionally thick nearshore coarse-grained deltaic and estuarine successions (acoustic unit 4) were deposited. The uppermost postglacial sediment (acoustic unit 5) forms the seabed and reflects a reworking phase concomitant with a lowering sea level and ablating Late Wisconsinan ice sheets.Glacioisostatic rebound, which occurred about 23 ka to the present, uplifted glacial and marine deposits and resulted in extensive reworking and production of modern placers. Heavy-mineral concentrations vary as follows: terrestrial tills, 9–20%; modem storm-berm and delta top deposits, 43–60%; delta slope deposits, 25–55%; and deep (170+ m) offshore sediments, 0–2%. Three stages occurred in marine placer formation: (1) 6700 BP, fluvial discharge was high, and fluvial-dominated deltas were built; marine limit was 30 m asl, with progradation of deltas and delivery of sediments with at most 2% heavy minerals; (2) 5200 BP, fluvial discharge was reduced; marine limit was 15 m asl, deltaic sediments were reworked, increasing heavy mineral concentration to 2–8%; (3) 2800 BP, fluvial input was greatly reduced, waves and tides were more influential, a strong littoral current system developed, causing significant reworking of nearshore sediments, heavy mineral concentrations increased, with values exceeding 20% locally. Mass budget calculations show that the second-cycle reworked sediment (acoustic unit 5) is a potential economic target (1 km3, or 1700 Mt). If 7% (using atomic weights) of this target sediment is ilmenite (FeTiO3). then 27 Mt of titanium may be available.
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Nicholson, Uisdean, Andrew Carter, Paula Robinson, and David I. M. Macdonald. "Eocene–Recent drainage evolution of the Colorado River and its precursor: an integrated provenance perspective from SW California." Geological Society, London, Special Publications 488, no. 1 (December 20, 2018): 47–72. http://dx.doi.org/10.1144/sp488-2019-272.
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AbstractThe Colorado River in the SW of the USA is one of Earth's few continental-scale rivers with an active margin delta. Deformation along this transform margin, as well as associated intra-plate strain, has resulted in significant changes in sediment routing from the continental interior and post-depositional translation of older deltaic units. The oldest candidate deposits, fluvial sandstones of the Eocene Sespe Group, are now exposed in the Santa Monica Mountains, 300 km to the north of the Colorado River. Heavy mineral data from this basin indicate that sediment was sourced by a large river system, with some affinity to the early Pliocene Colorado River, but was unlikely to have been integrated across the Colorado Plateau. Sedimentological and mineralogical evidence from the earliest (c. 5.3 Ma) unequivocal Colorado River-derived sediments in the Salton Trough provide evidence for a rapid transition from locally derived sedimentation. Lack of evidence for a precursor phase of suspended-load sediment suggests that drainage capture took place in a proximal position, favouring a ‘top-down’ process of lake spillover. Following drainage integration, significant changes in heavy mineral assemblages of fluvio-deltaic sediments, particularly evident from apatite–tourmaline and garnet–zircon indices, as well as U–Pb ages of detrital zircons, document the integration of the fluvial system to its present form and progressive incision of the Colorado Plateau from the Miocene to the present.
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Désy, JC, J. F. Archambault, B. Pinel-Alloul, J. Hubert, and P. GC Campbell. "Relationships between total mercury in sediments and methyl mercury in the freshwater gastropod prosobranch Bithynia tentaculata in the St. Lawrence River, Quebec." Canadian Journal of Fisheries and Aquatic Sciences 57, S1 (March 14, 2000): 164–73. http://dx.doi.org/10.1139/f99-231.
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Total Hg concentrations in sediment and methyl mercury (MeHg) levels in the gastropod species Bithynia tentaculata were evaluated at 21 stations in the fluvial corridor of the St. Lawrence River (Quebec, Canada). In the sediments (n = 21), total Hg concentrations ranged from 34 to 2790 ng·g dry weight-1. In the gastropods, MeHg concentrations varied from 15 to 290 ng·g dry weight-1 in undepurated gastropods (n = 20) and from 41 to 420 ng·g dry weight-1 in depurated gastropods (n = 13; without gut contents). The southern sector of Lake St. Louis, located near the Îles-de-la-Paix, had significantly higher Hg concentrations than any other sectors under study, both for total Hg in the sediments and MeHg in the gastropods. We established linear models to describe the relationships between Hg contamination in sediments and molluscs for the fluvial corridor of the St. Lawrence River and for the Lake St. Louis sector. Total Hg in sediments and MeHg in gastropods were highly correlated for all pooled stations (r = 0.83), and the relationship was even stronger for the Lake St. Louis stations (r = 0.92). Our study suggests that the gastropod B. tentaculata is a promising biomonitor species for assessing Hg contamination in the fluvial corridor and lakes of the St. Lawrence River.
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Jones, MR. "Surficial sediments of the western Gulf of Carpentaria, Australia." Marine and Freshwater Research 38, no. 1 (1987): 151. http://dx.doi.org/10.1071/mf9870151.
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Modern sedimentation in the Gulf of Carpentaria is confined principally to marginal areas in water depths of less than 50 m. Within this zone, the distribution of sediments is irregular, being controlled by proximity to sediment sources and degree of exposure to waves and tidal activity. This is particularly so in the western gulf, where fluvial sediments supplied to Limmen Bight have been transported by waves and tides northwards beyond that embayment to accumulate in the sheltered environment of Blue Mud Bay. Limmen Bight is exposed to the south-easterlies, which produce sufficient wave action in the nearshore zone to prevent the widespread deposition of fine-grained terrigenous sediments. As a result, relict sand deposits occupy much of the floor of Limmen Bight in areas shallower than about 25 m. In deeper areas, terrigenous muds are deposited at a low rate over relict fluvial and marine sediments. The relict deposits accumulated in continental and nearshore marine environments during low-sea-level periods of the late Pleistocene.
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Álvarez-Vázquez, Miguel Ángel, and Elena De Uña-Álvarez. "An exploratory study to test sediments trapped by potholes in Bedrock Rivers as environmental indicators (NW Iberian Massif)." Cuaternario y Geomorfología 35, no. 1-2 (June 21, 2021): 59–77. http://dx.doi.org/10.17735/cyg.v35i1-2.89054.
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The capacity of fluvial potholes to trap sediments, together with the geochemical analysis of their stored sediments for environmental assessment, is an overlooked research topic in small bedrock rivers. The present exploratory study is focused on this issue. It was developed in a small river over rock, in the inland territory of Galicia (NW Iberian Peninsula). The study started from an analysis of the inventoried fluvial potholes to identify suitable forms for sampling, and the collection of sediment samples within them. After this, the determination of the grain texture, mineralogy and content of major and trace elements in sediments were carried out. Potholes with maximum vertical depth from 25 cm to 1 m, located in central and sidewall sectors of the bedrock channel, provided the best conditions for sediment sampling. The sediments collected from six potholes showed predominance of coarse-medium grain size and sand fraction. The rough contents of the major and even trace elements are related with the nature of the more refractory minerals of the bedrock. An adequate sampling strategy, considering grain-size fractions, show potential to use trace elements as environmental indicators.
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Vignaga, Elisa, David M. Sloan, Xiaoyu Luo, Heather Haynes, Vernon R. Phoenix, and William T. Sloan. "Erosion of biofilm-bound fluvial sediments." Nature Geoscience 6, no. 9 (August 4, 2013): 770–74. http://dx.doi.org/10.1038/ngeo1891.
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Corner, Geoffrey D. "Fluvial sediments: archives of environmental change." Boreas 31, no. 3 (September 1, 2002): 302. http://dx.doi.org/10.1080/030094802760260409.
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Meyer, Patricia A., and Carolyn H. Eyles. "Nature and origin of sediments infilling poorly defined buried bedrock valleys adjacent to the Niagara Escarpment, southern Ontario, Canada." Canadian Journal of Earth Sciences 44, no. 1 (January 1, 2007): 89–105. http://dx.doi.org/10.1139/e06-085.
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The buried Paleozoic bedrock surface of southern Ontario is dissected by an interconnected system of valleys. These buried valleys are infilled with thick successions of glacial, interglacial, and fluvial sediments that contain a lengthy record of changing environmental conditions during the late Quaternary. Detailed logging of over 500 m of sediment recovered from 11 continuously cored boreholes provides the basis for this study. The boreholes were drilled within two poorly defined bedrock valleys located east of the Niagara Escarpment in southern Ontario as part of a groundwater exploration program. Six distinct facies types were identified within the cores: sand, gravel, fine-grained sediment, and sand-rich, mud-rich, and clast-rich diamict. Textural characteristics of the cored sediments and vertical changes in facies types were used to identify six stratigraphic units (SU I through SU VI) within the valley-infill deposits. These units are interpreted to record fluvial or colluvial (SU I), lacustrine (SU II), fluvial, glaciofluvial or deltaic (SU III), subglacial (SU IV), glaciofluvial (SU V) and subglacial or ice marginal (SU VI) conditions. Sediment characteristics and stratigraphic relationships allow tentative correlation with known surficial deposits. Analysis of the subsurface characteristics and geometries of this stacked succession of coarse- and fine-grained stratigraphic units also allows identification of the geometry of potential aquifers.
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Miura, Hideki, Kiichi Moriwaki, Hideaki Maemoku, and Kazuomi Hirakawa. "Fluctuations of the East Antarctic ice-sheet margin since the last glaciation from the stratigraphy of raised beach deposits along the Sôya Coast." Annals of Glaciology 27 (1998): 297–301. http://dx.doi.org/10.3189/1998aog27-1-297-301.
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The fluctuation of the East Antarctic ice-shect (EAIS) margin and relative sea-level change since the last glaciation are discussed from the stratigraphy and TAMS 14C ages of raised beach deposits in the northern part of the Soya Coast.The beach deposits reveal two marine sediment layers with in situ fossil shells of Laternula elliptica, and an interbedded fluvial sediment layer. The l4C ages of fossils in the lower, older marine beds ranged from 36 to 43 ka, and in the upper, younger beds from 4.9 to 5.2 ka without reservoir correction. Neither marine layers nor in situ fossil shells were disturbed by ice-sheet loading or scouring. The interbedded fluvial sediments appear to have been deposited by a stronger fluvial process than present meltwater activity in the area. These facts lead us to the following conclusions: (1) marine transgression occurred during the last interstadial around 40 ka or the Last Intcrglacial, and in the Holocene around 5 ka: (2) the EATS possibly retreated from the northern Sôya Coast prior to the Last Glaciol Maximum (LGM); (3) the fluvial process may have occurred during a period of low sea level which may have been a warmer period than the present, probably during the late-Glaciol to postglaciol age; and (4) the EAIS did not rcadvance over these sediments during or since the LGM.
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Carranza-Edwards, Arturo, Leticia Rosales-Hoz, and Susana Santiago-Pérez. "Provenance memories and maturity of holocene sands in northwest Mexico." Canadian Journal of Earth Sciences 31, no. 10 (October 1, 1994): 1550–56. http://dx.doi.org/10.1139/e94-137.
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Beach and fluvial sediments from the region around Todos Santos Bay, Baja California, have been studied to determine their maturity, provenance, chemical alteration, and tectonic relationships. Analysis of the CaO–Na2O–K2O content of several samples demonstrated a difference between those from a beach environment and those from a fluvial environment. Transport affects the characteristics of the sediment, producing an enrichment of material resistant to chemical and physical attack on the beach area. The beach sand samples are mineralogically and chemically more mature than those from the fluvial sands. The provenance index (feldspar/rock fragments) gives relatively low average values for fluvial sands, provided that they are richer in rock fragments. The chemical index of alteration has low average values for beach sands because the minerals are more resistant to energy from waves and currents. Tectonic settings, defined through the binary diagram from Roser and Korsch, suggest that the samples belong to active continental margin and arc domains. When tectonic fields are assigned, based on a Q–F–L triangular diagram analysis, the sediments from the study area fall in an active magmatic arc field, even though this region is not presently subject to subduction.
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Kirk, M. "Westphalian alluvial plain sedimentation, Isle of Arran, Scotland." Geological Magazine 126, no. 4 (July 1989): 407–21. http://dx.doi.org/10.1017/s0016756800006592.
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AbstractFacies analysis suggests that Westphalian (Upper Carboniferous) Coal Measure sequences on the Isle of Arran, Scotland, were deposited in a proximal alluvial plain environment close to the basin margin. Detailed examination of well exposed coastal sections has revealed the existence of six laterally and vertically interrelated sedimentary facies. Facies 1 to 3 are interpreted as fluvial channel deposits. Low sinuosity multistorey (facies 1), low sinuosity vertically accreted (facies 2), and rare high sinuosity laterally accreted channel deposits (facies 3) are developed. Associated overbank sediments comprise the deposits of crevasse splays (facies 4), flood plains (facies 5) and shallow lakes (facies 6). In terms of the spatial distribution of facies, a relatively high proportion of fluvial channel and floodplain deposits (facies 2 and 5) occur in the more proximal sequence at Laggan compared with the more distally located sequence occurring at Corrie. Palaeocurrent measurements from fluvial channel sandstones indicate that sediment source areas and the Westphalian basin margin lay to the north and northwest. Down palaeoslope towards the southeast, normal coal-bearing Westphalian sediments formed penecontemporaneously on the Scottish mainland in Ayrshire.A sedimentological model is presented for the proximal non-coal-bearing Westphalian sequences of Arran. This model can explain the differences observed between the Arran sediments, and contemporaneous normal coal-bearing Westphalian sediments of the Scottish mainland.
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Martínez-Mena, María, María Almagro, Noelia García-Franco, Joris de Vente, Eloisa García, and Carolina Boix-Fayos. "Fluvial sedimentary deposits as carbon sinks: organic carbon pools and stabilization mechanisms across a Mediterranean catchment." Biogeosciences 16, no. 5 (March 15, 2019): 1035–51. http://dx.doi.org/10.5194/bg-16-1035-2019.
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Abstract. The role of fluvial sedimentary areas as organic carbon sinks remains largely unquantified. Little is known about mechanisms of organic carbon (OC) stabilization in alluvial sediments in semiarid and subhumid catchments where those mechanisms are quite complex because sediments are often redistributed and exposed to a range of environmental conditions in intermittent and perennial fluvial courses within the same catchment. The main goal of this study was to evaluate the contribution of transport and depositional areas as sources or sinks of CO2 at the catchment scale. We used physical and chemical organic matter fractionation techniques and basal respiration rates in samples representative of the three phases of the erosion process within the catchment: (i) detachment, representing the main sediment sources from forests and agricultural upland soils, as well as fluvial lateral banks; (ii) transport, representing suspended load and bedload in the main channel; and (iii) depositional areas along the channel, downstream in alluvial wedges, and in the reservoir at the outlet of the catchment, representative of medium- and long-term residence deposits, respectively. Our results show that most of the sediments transported and deposited downstream come from agricultural upland soils and fluvial lateral bank sources, where the physicochemical protection of OC is much lower than that of the forest soils, which are less sensitive to erosion. The protection of OC in forest soils and alluvial wedges (medium-term depositional areas) was mainly driven by physical protection (OC within aggregates), while chemical protection of OC (OC adhesion to soil mineral particles) was observed in the fluvial lateral banks. However, in the remaining sediment sources, in sediments during transport, and after deposition in the reservoir (long-term deposit), both mechanisms are equally relevant. Mineralization of the most labile OC (the intra-aggregate particulate organic matter (Mpom) was predominant during transport. Aggregate formation and OC accumulation, mainly associated with macroaggregates and occluded microaggregates within macroaggregates, were predominant in the upper layer of depositional areas. However, OC was highly protected and stabilized at the deeper layers, mainly in the long-term deposits (reservoir), being even more protected than the OC from the most eroding sources (agricultural soils and fluvial lateral banks). Altogether our results show that both medium- and long-term depositional areas can play an important role in erosive areas within catchments, compensating for OC losses from the eroded sources and functioning as C sinks.
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Porzionato, Natalia, Mariangeles Mellota, Roberto Candal, and Gustavo Curutchet. "Acid Drainage and Metal Bioleaching by Redox Potencial Changes in Heavy Polluted Fluvial Sediments." Advanced Materials Research 825 (October 2013): 496–99. http://dx.doi.org/10.4028/www.scientific.net/amr.825.496.
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Sediments from polluted urban streams act as a sink of contaminants. The high content of organic matter and sulphides makes the system appropriate for binding heavy metals. However, changes in the redox potential leads to processes in which sediments acts like a low sulphidic ore in an oxidizing environment, and could generate acid drainages. Human and not human disturbances of the sediments could derive in its oxidation catalyzed by sulphur oxidizing bacteria (SOB). This process leads to acidification and metal release. In this study we analyze the acidification potential of anaerobic sediments of polluted streams near Buenos Aires with static and kinetic methods. The results remark the necessity to consider this process before any sediment management action.
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Armstrong, Shalamar, Douglas Smith, Phillip Owens, Brad Joern, April Leytem, Chi Huang, and Olayiwola Adeola. "Phosphorus and nitrogen loading depths in fluvial sediments following manure spill simulations." Canadian Journal of Soil Science 91, no. 3 (June 2011): 427–36. http://dx.doi.org/10.4141/cjss10003.
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Armstrong, S. D., Smith, D. R., Owens, P. R., Joern, B. C., Leytem, A. B., Huang, C.H. and Adeola, L. 2011. Phosphorus and nitrogen loading depth in fluvial sediments following manure spill simulations. Can. J. Soil Sci. 91: 427–436. The depth of nitrogen (N) and phosphorus (P) loading in fluvial sediments following a manure spill has not been documented. Thus, the objectives of this study were: (i) to determine the depth of N and P enrichment as a result of a manure spill under base flow conditions using fluvarium techniques and (ii) to evaluate the impact of sediment particle size distribution on N and P enrichment depth. Manure spills were simulated using stream simulators and ditch sediments collected from agricultural drainage ditches. During the manure spill simulation, the P sorption capacity of all sediments exponentially decreased with time and the NH4-N sorption capacity remained constant with time. The P and NH4-N loading in all sediments were observed to the depth of 2 cm, but were most concentrated in the 0- to 1-cm depth ranging in concentrations from 3 to 12 mg P kg−1 and from 7.2 to 45 mg NH4-N kg−1. Data from this study give a basis for the advancement of manure spill remediation that will reduce the impairment of surface waters via the release of nutrients from enriched sediments following a manure spill.
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Dyke, Arthur S., and John V. Matthews. "Stratigraphy and Paleoecology of Quaternary Sediments Along Pasley River, Boothia Peninsula, Central Canadian Arctic." Géographie physique et Quaternaire 41, no. 3 (December 18, 2007): 323–44. http://dx.doi.org/10.7202/032689ar.
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ABSTRACT Quaternary sediments exposed along Pasley River consist of a lower marine deltaic sand overlain in succession by complexly interbedded tills and glaciomarine sediments (the lower glacigenic assemblage), by a mid-section fluvial gravel, by an upper marine deltaic sand, and by glaciomarine sediment and till (the upper glacigenic assemblage). The midsection fluvial gravels contain plant and insect fossils indicating a climate as warm as and perhaps warmer than present. The top of the gravel is more than 55 000 years old ; the unit is probably of Sangamonian age (>75 000 ka) and separates Wisconsinan from lllinoian glacial deposits. The deltaic sands that underlie both glacigenic assemblages indicate substantial crustal depression during glacial buildup episodes prior to arrival of ice at the site. This implies that the process of buildup was slow and involved glacier expansion into major marine basins. Glaciomarine beds of the lower glacigenic assemblage locally contain abundant detrital terrestrial organic material as well as marine molluscs. The terrestrial organic detritus, an unusual constituent of glaciomarine sediment, is thought to have been released into the sea from glacier ice. These terrestrial fossil asemblages exhibit compositional differences which vary with the sediment faciès and probably reflect taphonomic factors such as differential buoyancy of the fossils. The upper marine deltaic sands contain some "old " rebedded plant detritus and amber indicating a nearby source of Tertiary sediment, possibly equivalent in age to the Beaufort Formation. Other rebedded fossils from the upper deltaic unit may be the same age as the mid-section fluvial gravels.
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Bartyik, Tamás, Cristian Floca, Elemér Pál-Molnár, Petru Urdea, Diaa Elsayed Hamed, and György Sipos. "The Potential Use of Osl Properties of Quartz in Investigating Fluvial Processes on the Catchment of River Mureş, Romania." Journal of Environmental Geography 14, no. 1-2 (April 1, 2021): 58–67. http://dx.doi.org/10.2478/jengeo-2021-0006.
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Abstract To understand the functioning of fluvial systems it is important to investigate dynamics of sediment transport and the source of sediments. In case of reconstructing past processes these studies must be accompanied by the numerical dating of sediment samples. In this respect optically stimulated luminescence is a widely used technique, by which the time of sediment deposition can be directly dated. Recently, in various fluvial environments it has been shown that certain luminescence properties of minerals, and especially that of quartz, can be applied as indicators of fluvial erosion and/or sediment provenance. These properties are residual luminescence (or residual dose) and luminescence sensitivity of quartz grains. However, the values of the parameters above are affected by various factors, the importance of which is under debate. The present study therefore aims to assess these factors along a ~560 km long reach of River Mureş (Maros) a relatively large river with a compound surface lithology on its catchment. The research focused on the sandy fraction of modern sediments, collected from the main river and from three tributaries alike. This way not only longitudinal downstream changes, but the influence of tributaries could also be studied. Based on the data, both investigated parameters show a great variation, which can be attributed to the lithological differences of subcatchments and geomorphological drivers, such as erosional activity and potential number of sedimentary cycles, and human activity. However, relationships are not entirely clear and are influenced by the maximum grain size of the samples investigated, and the recycling of previously laid deposits with different properties. Still, when performing detailed dating studies, and tracing sediments from certain parts of the catchment luminescence properties can be a useful tool in the future.
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Liu, Shih-Hung, Robert Hebenstreit, and Margot Böse. "Late Quaternary landform evolution and sedimentary successions in the Miaoli Tableland, northwestern Taiwan." E&G Quaternary Science Journal 71, no. 1 (January 18, 2022): 1–22. http://dx.doi.org/10.5194/egqsj-71-1-2022.
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Abstract. Elevated Quaternary sedimentary complexes in the western foreland of the central mountain ranges of Taiwan are called tablelands. Their mostly flat surfaces are deeply incised by fluvial processes. The landforms and the fluvial systems in the Miaoli Tableland are investigated by high-resolution terrain analyses based on different datasets. Sediments are described in 51 outcrops and characterized by grain size composition. The outcrops revealed complete or incomplete sequences of the general scheme from bottom to top: sandy tidal–coastal units overlain by gravel- and cobble-rich fluvial deposits always with a fine-grained silt-rich top cover layer influenced by aeolian deposits. All layers are unconsolidated sediments. Three subtypes of this sequence were identified, with respect to the occurrence of the fluvial deposits. The relation of tectonic and erosional processes including the rework of gravels is discussed. The results reveal a tableland surface much more disaggregated than previously mapped, suggesting that individual tableland segments represent remnants of an inferred palaeotopography. The tableland surfaces have been separated into Sedimentary Highlands (SH-I and SH-II) and Sedimentary Terraces (ST) by geometrical properties. The Alluvial and Coastal Plains (AL) represent broad valley bottoms (“box-shaped valleys”) in the dendritic drainage systems below 150 m and the coastal plains. The landforms and predominantly the sediment sequences are discussed in the context of the existing stratigraphical schemes of the Toukoshan Formation and the so far rarely used Lungkang Formation. The latter is recommended as the stratigraphical term for the refined subdivision of the uppermost part of late Quaternary sediments in the Miaoli Tableland.
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HUYBRECHTS, Willy. "Post-pleniglacial floodplain sediments in Central Belgium." Quaternary geology of Belgium: new perspectives 2, no. 1-2 (April 1, 2000): 29–37. http://dx.doi.org/10.20341/gb.2014.009.
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This paper presents an outline of the floodplain sediments which dominated the river environment during the last 13,000 years in the western parts of Central Belgium. It is based on literature, with special reference to the Mark River basin. River landscapes and related floodplain sediments are a combined result of changing external factors such as climate and human activity, and prevailing local geological and topographical conditions. The development of the vegetation predominantly controls the sediment and water fluxes in the catchment. After the Pleniglacial, a system of palaeovalleys developed as a result of a non-equilibrium between vegetation and climate. For more than 10,000 years, this system dominated the river landscape, while gradually being filled with organic material and sediments. Three infilling phases can be distinguished: the Gully facies, the Organic and tufa facies, and the Fluvial clay facies. The Gully facies reflects an initial time period of fluvial activity, and occupies the lowermost parts of the palaeovalley. From 9000 BP onwards, forest swamps occupied the river plains, reflecting very stable conditions in the catchments. The Organic and tufa facies was formed. During the second half of the Atlanticum, from about 6000 BP onwards, human agricultural activities greatly affected the river landscape and the hydrological system. The forest swamps disappeared and were gradually replaced by open water. The deposition of the Fluvial clay facies concluded the filling of the palaeovalley. Medieval clearings in the catchments, less than 1200 years ago, disrupted the originally stable hydrological regime of the river. The Surface loam facies was deposited during inundations, independent of the palaeovalley system.
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Silva, Adriana cassiano, and Osvaldo Girão da Silva. "ANALISES DOS PADRÕES E ESTILOS DE CANAIS A PARTIR DA PAISAGEM GEOMORFOLÓGICA FLUVIAL NA BACIA DO RIO UNA/PE." Revista Cerrados 14, no. 02 (March 18, 2020): 71–92. http://dx.doi.org/10.22238/rc24482692v14n22016p71a92.
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Os estilos fluviais refletem a fisiografia estrutural da rede de drenagem controladas pelos estratos rochosos, retratando na paisagem sua dinâmica, assim como os padrões de canais, que podem ser alterados por processos geomorfológicos, climáticos e antrópicos. O quadro dos estilos fluvial fornece um modelo geomorfológico dos processos espaciais e temporais biofísicos para gestão e planejamento das bacias hidrográficas. O presente trabalho teve como objetivo analisar as influências do comportamento no canal da bacia do rio Una localizado no Nordeste do Estado de Pernambuco, a partir da investigação das feições da drenagem como reflexo da transferência de matéria e energia entre distintos compartimentos e setores do ambiente fluvial. A metodologia proporcionou uma visão geral de toda área analisada, a partir da avaliação do índice de sinuosidade, mapeamento dos estilos e das feições fluviais, perfis longitudinais e trabalhos de observação em campo. Assim, constatou-se que a influência estrutural na rede de drenagem da referida bacia comandou a retilineidade do canal Una, com quebra no gradiente topográfico, inflexão do canal e vales encaixados. Nesse ambiente, verificou-se que a produção e deposição dos sedimentos estão vinculados as influências do clima tropical.
Palavras-Chave: Feição Fluvial; Estrutura; Instabilidade; Deposição de Sedimentos.
ANALYSIS OF PATTERNS AND CHANNEL STYLE FROM THE LANDSCAPE GEOMORPHOLOGICAL FLUVIAL IN RIVER BASIN UNA/ PE
Abstract
The river styles reflect the structural physiography drainage network controlled by the rock strata, depicting the landscape dynamics, as well as channel patterns, which can be changed by geomorphological, climatic and anthropogenic processes. The fluvial styles of the table provides a geomorphological model of spatial processes and biophysical time for planning and management of river basins. This study aimed to analyze the influence of behavior on the channel of the river basin Una located in the northeastern state of Pernambuco, from the investigation of drainage features reflecting the transfer of matter and energy between different compartments and sections of the river environment. The methodology provided an overview of the whole analyzed area, from the evaluation of the sinuosity index, mapping styles and river features, longitudinal profiles and field observation work. Thus, it was found that the structural influence on the basin drainage network commanded the straightness of Una channel, breaking the topographic gradient, channel inflection and enclosed valleys. In this environment, it found that the production and deposition of sediments are bound influences the tropical climate.
Keywords: Fluvial feature, structure, Instability, Deposition of Sediments.
ANÁLISIS DE PATRONES Y CANALES DE ESTILOS DE PAISAJE DEL RÍO GEOMORFOLÓGICO EN UNA DE CUENCA / PE
Resumen
Los estilos de los ríos reflejan la red estructural de drenaje fisiografía controlado por los estratos de roca, que representa la dinámica del paisaje, así como los patrones de canal, que puede ser cambiado por procesos geomorfológicos, climáticos y antropogénicos. Los estilos fluviales de la tabla proporciona un modelo geomorfológico de los procesos espaciales y el tiempo biofísico para la planificación y gestión de las cuencas hidrográficas. Este estudio tuvo como objetivo analizar la influencia del comportamiento en el canal de la cuenca del río Una ubicada en el nororiental estado de Pernambuco, a cercar de la investigación de las características de drenaje que refleja la transferencia de materia y energía entre los distintos compartimentos y secciones del entorno del río. La metodología proporciona una visión general de toda la zona analizada, de la evaluación del índice de sinuosidad, la cartografía de estilos y características de ríos, perfiles longitudinales y trabajos de observación de campo. Por lo tanto, se encontró que la influencia estructural en la red de drenaje cuenca mandó la rectitud de canal Una, rompiendo el gradiente topográfico, la inflexión del canal y valles cerrados. En este entorno, se encontró que la producción y deposición de sedimentos están obligados influencias del clima tropical.
Palabras clave: río de funciones; la estrutura; la inestabilidad; la deposición de sedimentos.
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Balatka, Břetislav, and Jaroslava Loučková. "Quaternary Terraces of the Berounka River." Geografie 96, no. 3 (1991): 145–62. http://dx.doi.org/10.37040/geografie1991096030145.
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The paper brings geomorphological characteristic of Neogene sediments and Pleistocene terraces of the Berounka (the left tributary to the Vltava). The localities of Neogene fluvial and fluvial-lacustrine sediments of Lower Miocene Age are clean-cut and neotectonically dislocated. The Pleistocene terraces (13 levels in 7 groups), diverging downstream, have been incorporated into the stratigraphical Pleistocene system.
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Droppo, Ian G. "Biofilm structure and bed stability of five contrasting freshwater sediments." Marine and Freshwater Research 60, no. 7 (2009): 690. http://dx.doi.org/10.1071/mf08019.
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Using an annular flume, erosion characteristics of five diverse sediment types (stormwater pond, contaminated lacustrine, fluvial, aquaculture waste and industrial grade kaolin sediment), each with different physical and biological characteristics, were examined for relative erosion resistance and factors contributing to bed sediment stability. Suspended flocs represent primary building blocks of bed sediment with mass settling being independent of suspended solid concentration. Biofilm growth period, depositing floc structure and composition, nutrient supply and sediment properties all played a complex role in dictating the stability of the sediments. The river, lake and stormwater pond sediments were the most resistant to erosion relative to the high nutrient and organic content aquaculture sediment and kaolin. Biofilms developed to varying degrees on all sediments with the greatest growth occurring with the aquaculture sediment and the least with kaolin. While electrochemical properties will provide some attraction and stabilising forces, with no measurable consolidation evident for the examined sediments, it is suggested that active biofilm development was the dominant factor controlling bed stability and erosion potential. Differences in biological mediation of strength between sediments were partially attributed to the structural differences within the biofilms and integration of the extracellular polymeric fibril matrix within the sediment pores.
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Lake, Randal G., and Scott G. Hinch. "Acute effects of suspended sediment angularity on juvenile coho salmon (Oncorhynchus kisutch)." Canadian Journal of Fisheries and Aquatic Sciences 56, no. 5 (May 1, 1999): 862–67. http://dx.doi.org/10.1139/f99-024.
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To determine the roles of suspended sediment angularity and concentration as contributors to stress and mortality in salmonids, we exposed juvenile coho salmon (Oncorhynchus kisutch) to anthropogenically derived "extremely angular" and "round" silicate sediments over a range of concentrations in 96-h experiments. Stress responses (e.g., decreased leukocrit) were elicited by exposure to both sediment shapes when concentrations were >40 g·L-1, corresponding to the minimum concentration at which physical gill damage was observed. Extremely angular sediments also caused stress responses (e.g., elevated hematocrit, decreased leukocrit) at concentrations <41 g·L-1. However, we found no difference between sediment shapes in causing mortality at any sediment concentration. Further, mortalities were not observed until concentrations were about 100 g·L-1, a value that is about an order of magnitude greater than high natural concentrations in salmonid rivers. Natural fluvial suspended sediments cause fish stress and mortality at much lower concentrations than we found with our anthropogenically derived suspended sediments.
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Ryder, June M., and Michael Church. "The Lillooet terraces of Fraser River: a palaeoenvironmental enquiry." Canadian Journal of Earth Sciences 23, no. 6 (June 1, 1986): 869–84. http://dx.doi.org/10.1139/e86-089.
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The history of Holocene fluvial terraces was investigated by stratigraphic, morphological, and palaeohydrologic methods. The terraces were formed in glaciofluvial and glaciolacustrine sediments by the Fraser River: degradation alternated with episodes of stability and aggradation. The uppermost terraces, four nonpaired surfaces, were occupied by a braided river. Vertical stability was controlled either by the water and sediment discharge of the river or by backwater effects from downstream landslides. The lower terraces, two paired surfaces, and associated fluvial sediments provide evidence for at least two cycles of aggradation and downcutting. These can be attributed to the effects of landslides that occurred a short distance downstream. Climatic variations may also have influenced terrace formation, but direct evidence is lacking. Palaeohydraulic investigations based on gravel texture, terrace gradients, and geometry of palaeochannels provide results that although approximate, conform with conclusions based upon terrace morphology and stratigraphy.
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Zang, Zhengchen, Z. George Xue, Kehui Xu, Samuel J. Bentley, Qin Chen, Eurico J. D’Sa, and Qian Ge. "A Two Decadal (1993–2012) Numerical Assessment of Sediment Dynamics in the Northern Gulf of Mexico." Water 11, no. 5 (May 4, 2019): 938. http://dx.doi.org/10.3390/w11050938.
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We adapted the coupled ocean-sediment transport model to the northern Gulf of Mexico to examine sediment dynamics on seasonal-to-decadal time scales as well as its response to decreased fluvial inputs from the Mississippi-Atchafalaya River. Sediment transport on the shelf exhibited contrasting conditions in a year, with strong westward transport in spring, fall, and winter, and relatively weak eastward transport in summer. Sedimentation rate varied from almost zero on the open shelf to more than 10 cm/year near river mouths. A phase shift in river discharge was detected in 1999 and was associated with the El Niño-Southern Oscillation (ENSO) event, after which, water and sediment fluxes decreased by ~20% and ~40%, respectively. Two sensitivity tests were carried out to examine the response of sediment dynamics to high and low river discharge, respectively. With a decreased fluvial supply, sediment flux and sedimentation rate were largely reduced in areas proximal to the deltas, which might accelerate the land loss in down-coast bays and estuaries. The results of two sensitivity tests indicated the decreased river discharge would largely affect sediment balance in waters around the delta. The impact from decreased fluvial input was minimum on the sandy shoals ~100 km west of the Mississippi Delta, where deposition of fluvial sediments was highly affected by winds.
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Micić, Vesna, Jürgen Köster, Michael A. Kruge, Bert Engelen, and Thilo Hofmann. "Bacterial wax esters in recent fluvial sediments." Organic Geochemistry 89-90 (December 2015): 44–55. http://dx.doi.org/10.1016/j.orggeochem.2015.10.003.
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Liu, Zhifei, and Karl Stattegger. "South China Sea fluvial sediments: An introduction." Journal of Asian Earth Sciences 79 (January 2014): 507–8. http://dx.doi.org/10.1016/j.jseaes.2013.11.003.
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Harvey, Gemma L., Tom P. Moorhouse, Nicholas J. Clifford, Alexander J. Henshaw, Matthew F. Johnson, David W. Macdonald, Ian Reid, and Stephen P. Rice. "Evaluating the role of invasive aquatic species as drivers of fine sediment-related river management problems: The case of the signal crayfish (Pacifastacus leniusculus)." Progress in Physical Geography: Earth and Environment 35, no. 4 (May 10, 2011): 517–33. http://dx.doi.org/10.1177/0309133311409092.
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Sediment quantity and quality are key considerations in the sustainable management of fluvial systems. Increasing attention is being paid to the role of aquatic biota as geomorphic agents, capable of altering the composition, mobilization and transport of fluvial sediments at various spatiotemporal scales. In this paper invasive species are presented as a special case since: (1) populations may not be constrained by factors characteristic of their native habitats; and (2) they represent a disturbance to which the system may not be resilient. Discussion is centred on the signal crayfish which has rapidly colonized catchments in Europe and Japan, but the hypotheses and models presented provide a framework applicable to other invasive species. This paper explores the mechanisms by which signal crayfish may influence sediment dynamics from the patch scale to the catchment scale. There is potential for signal crayfish to impact significantly on river sediments and morphology as a function of their interactions with river bed and bank material, and with other aquatic organisms, combined with their large body size and aggressive nature, their presence in very high densities, and the lack of effective mitigation strategies. Potential catchment-scale management issues arising from these factors include habitat degradation, mobilization of sediment-associated nutrients and contaminants, and sediment-related flood risks. Further interdisciplinary research is required at the interface between freshwater ecology, fluvial geomorphology and hydraulics, in order to quantify the significance and extent of these impacts. The paper points to the key research agendas that may now emerge.
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Bliedtner, Marcel, Hans von Suchodoletz, Imke Schäfer, Caroline Welte, Gary Salazar, Sönke Szidat, Mischa Haas, Nathalie Dubois, and Roland Zech. "Age and origin of leaf wax <i>n</i>-alkanes in fluvial sediment–paleosol sequences and implications for paleoenvironmental reconstructions." Hydrology and Earth System Sciences 24, no. 4 (April 28, 2020): 2105–20. http://dx.doi.org/10.5194/hess-24-2105-2020.
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Abstract. Leaf wax n-alkanes are increasingly used for quantitative paleoenvironmental reconstructions. However, this is complicated in sediment archives with associated hydrological catchments since the stored n-alkanes can have different ages and origins. 14C dating of the n-alkanes yields independent age information for these proxies, allowing their correct paleoenvironmental interpretation. This also holds true for fluvial sediment–paleosol sequences (FSPSs) that integrate two different n-alkane signals: (i) a catchment signal in fluvial sediments and (ii) an on-site signal from local biomass that increasingly dominates (paleo)soils with time. Therefore, the age and origin of n-alkanes in FSPSs are complex: in fluvial sediment layers they can be pre-aged and reworked when originating from eroded catchment soils or from organic-rich sediment rocks in the catchment. In (paleo)soils, besides an inherited contribution from the catchment, they were formed on-site by local biomass during pedogenesis. Depending on the different relative contributions from these sources, the n-alkane signal from an FSPS shows variable age offsets between its formation and final deposition. During this study, we applied compound-class 14C dating to n-alkanes from an FSPS along the upper Alazani in eastern Georgia. Our results show that preheating the n-alkanes with 120 ∘C for 8 h before 14C dating effectively removed the shorter chains (<C25) that partly originate from n-alkanes from Jurassic black clay shales in the upper catchment. The remaining petrogenic contributions on the longer chains (≥C25) were corrected for by using a constant correction factor that was based on the n-alkane concentrations in a black clay shale sample from the upper catchment. Due to different degrees of pre-aging and reworking, the corrected leaf wax n-alkane ages still indicate relatively large age offsets between n-alkane formation and deposition: while intensively developed (paleo)soils showed no age offsets due to a dominance of leaf wax n-alkanes produced on-site, less intensively developed paleosols showed much larger age offsets due to larger proportions of inherited leaf wax n-alkanes from the fluvial parent material. Accordingly, age offsets in nonpedogenic fluvial sediments were largest and strongly increased after ∼4 ka cal BP. The leaf wax n-alkane homolog distribution from intensively developed (paleo)soils indicates a local dominance of grasses and herbs throughout the Holocene, which was most likely caused by anthropogenic activity. The leaf wax n-alkanes from fluvial sediments show a dominance of deciduous trees and shrubs as well as grasses and herbs in different parts of the catchment between ∼8 and ∼5.6 ka cal BP. Since no older deciduous tree- or shrub-derived n-alkanes were dated, this seems to confirm a delayed regional postglacial reforestation of parts of the catchment compared with western and central Europe.
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Arditto, P. A. "A SEQUENCE STRATIGRAPHIC STUDY OF THE CALLOVIAN FLUVIO-DELTAIC TO MARINE SUCCESSION WITHIN THE ZOCA REGION." APPEA Journal 36, no. 1 (1996): 269. http://dx.doi.org/10.1071/aj95015.
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This paper presents the results and conclusions of an integrated sequence stratigraphic study of the Callovian marine succession across area 'A' of the Zone of Cooperation (ZOCA). This study utilised wireline log and conventional core data from within ZOCA 91–1 and ZOCA 91–12, and incorporated trade data from adjacent permits, to generate a rational depositional model for the succession. Three distinct third-order sequences have been recognised from the detailed correlation of regional flooding surfaces recognised on wireline log motifs calibrated against conventional core and biostratigraphy. The base of the oldest third-order sequence includes section previously referred to as Plover Formation, and roughly corresponds to the W.digitata/W.indotata zone boundary. The Callovian Unconformity within the ZOCA region is thus relegated to a third-order sequence boundary or disconformity. The term Elang Formation is proposed for this Callovian succession which comprises three third-order sequences mappable across ZOCA. The well-type section for the Elang Formation is Elang-1, and an additional well reference section would be Elang-2, as both these wells contain significant and complementary cored section.Detailed sedimentological studies on conventional core reveal that the Elang Formation comprises a succession of coastal plain to nearshore marine sediments, ranging from low sinuosity fluvial channel, fluvial-dominated deltaic, proximal low sinuosity estuarine channel and distal outer bay sediments. Only minor wave-dominated, open marine shoref ace intervals were interpreted, most of the cored intervals indicating a fluvially-domi-nated shoreline with minimal wave reworking. Isopach and per cent sand maps generated for each third-order sequence comprising the Elang Formation illustrate the successive sediment distribution patterns across ZOCA during the progressive marine transgression from the top of the fluvio-deltaic Plover Formation to the base of the offshore marine Lower Flamingo Group. The sand-trend maps for the three sequences which comprise the Elang Formation indicate a fluvial/estuarine-dominated delta system, sourced from the region of the Laminaria Field, AC/P8, building east and southeast out across the ZOCA region. A modern analogue of this delta system in both size and sedimentation style may be the Brahmaputra/Ganges Delta of East Bengal.
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Govenor, Heather, W. Cully Hession, Tyler A. Keys, C. Nathan Jones, Ryan D. Stewart, and Leigh-Anne H. Krometis. "Evaluating Rare Earth Elements as Tracers of Fluvial Processes: Fine Sediment Transport and Deposition in a Small Stream." Transactions of the ASABE 64, no. 3 (2021): 905–18. http://dx.doi.org/10.13031/trans.14358.
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HighlightsNatural sediments labeled with rare earth elements can effectively be used as tracers for quantifying fine sediment transport and deposition.Two artificial floods in a small stream (100 ha watershed, 1.5 year return flow of 515 L s-1) transported fine sediment 0 m to >850 m at a maximum flow rate of 55 L s-1.Sediment deposition per unit area was greater in the channel than in the near-channel floodplain.Use of two distinct tracers demonstrated resuspension extent during sequential high-flow events.Presence of large wood in the channel was associated with reduced streamflow rate, decreased suspended sediment transport velocity, increased channel sediment deposition, and reduced near-floodplain sediment deposition.Abstract. Effective sediment management requires an understanding of the lag time between best management practice implementation and observable changes in the target water body. To improve our understanding of sediment lag times, we tested a method to label locally sourced sediments with rare earth elements to quantify fine sediment flow-through and storage in fluvial systems. We injected sediments labeled with lanthanum and ytterbium into a small stream during two artificial flood events. During the floods, we collected and quantified suspended sediments and sediment deposition in the stream channel and floodplain at four cross-sections within our study reach. Two down-gradient (90 m and 850 m) time-integrated suspended sediment samplers evaluated total travel distance. Sediment tracer observations of particle transport distances ranged from 0 m to at least 850 m at a maximum flow rate of 55 L s-1 (stream 1.5 year flow was 515 L s-1). Sediment deposition per unit area was greater in the channel than in the floodplain. The majority of sediment tracer mass injected into the stream entered storage within the first 69 m of the reach. Some particles that deposited following the first flood were resuspended and either transported downstream or redeposited within the study reach. Our results support the further use of rare earth elements as sediment tracers to inform water quality and sediment transport models, and to provide estimates of lag times between management actions and downstream improvements. Keywords: Fine sediment, Flood, Fluvial geomorphology, Lag time, Large wood, Rare earth elements, Sediment deposition, Sediment transport, Tracer.
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Gude, Martin, Christer Jonasson, Susanne Dietrich, and Dieter Scherer. "Assessment of Variability in Fluvial Sediment Transfers in Kärkevagge (N-Sweden) during the last 50 Years." Hydrology Research 31, no. 4-5 (August 1, 2000): 373–84. http://dx.doi.org/10.2166/nh.2000.0022.
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The Kärkevagge (Abisko area, Northern Sweden) represents a focus research basin concerning geomorphic processes and sediment budgets for the last 50 years. Different geomorphic process studies provide comparative data sets concerning climate variability implications on sediment transfers. While monitoring of sediment transfers is discontinuous with respect to study periods and methods, a detailed chronology of high-magnitude events with significant sediment displacement is available. In continuation of these studies, investigations in 1995 and 1998 as part of the MOSAIC project (Modelling Of Snowmelt And Its Consequences) are concentrating on snowmelt-induced slushflow initiation and transports of sediments in several small headwater catchments during the snowmelt period. Main purpose of the investigations is to characterize different catchment sections in terms of their hydrologic and sedimentologic contribution to the total fluvial and sediment budget of the basin, and to evaluate their specific sensitivity related to changes in atmospheric boundary conditions. By means of these data sets, the temporal variability of fluvial sediment transfers can be assessed over different time scales. The paper focuses on a description of different sections in the fluvial sediment transfer system in Kärkevagge. By comparing results from recent field investigations with data from former studies, the significance of rainfall- and snowmelt-triggered events for sediment transfers is evaluated.
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Andrews-Speed, C. P. "The role of silica and iron oxide mobility in the formation of gold-bearing fluvial sediments in the Proterozoic Mporokoso Basin, northern Zambia." Geological Magazine 123, no. 2 (March 1986): 143–52. http://dx.doi.org/10.1017/s0016756800029794.
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AbstractGold-bearing sandstone and conglomerate near the base of the Proterozoic Mporokoso Group were deposited in a braided river system. The detrital sand grade material is mainly of quartz, sericite and haematite, and the pebbles are of vein-quartz, chert, silicic volcanics, quartzose metasediment and jaspilite. The basement rocks presently exposed in the basement are silicic igneous rocks and quartzose metasediments.The petrography of the fluvial sediments suggests that silica and, to a lesser extent, iron oxide were mobile both in the source-area and in the braided river system. Evidence for silica-mobility includes jaspilite pebbles with spherulites and glaebules of chalcedony, abundant vein-quartz pebbles, intra-basinal sandstone pebbles, and the silicification of volcanic pebbles. The detrital haematite in the fluvial sandstone forms pseudomorphs after magmatic magnetite. Authigenic iron oxide occurs in several forms which suggest that iron oxide was mobile in the source-area and in the fluvial sediments. Uranium is locally abundant in basement and sedimentary rocks, cassiterite is a common heavy mineral in the fluvial sediments, and fluorite has been found in the basement.These features may be explained by intense weathering which mobilized both silica and iron. The silica was concentrated near the surface to form silcretes in the basement and later in the overlying fluvial sediments. Hydrothermal convection cells driven by the granites may have carried silica, iron, tin, fluorine and uranium towards the surface before and during the erosion of the igneous basement.