scholarly journals Influence of water and sediment supply on the stratigraphic record of alluvial fans and deltas: Process controls on stratigraphic completeness

2013 ◽  
Vol 118 (2) ◽  
pp. 625-637 ◽  
Author(s):  
Kyle M. Straub ◽  
Christopher R. Esposito
Keyword(s):  
Sediment Supply ◽  
Alluvial Fans ◽  
Water And Sediment ◽  
Stratigraphic Record ◽  
Influence Of Water ◽  
Process Controls

Influence of water and sediment quality on benthic biota in an acidified river

2005 ◽  
Vol 39 (12) ◽  
pp. 2517-2526 ◽  
Author(s):  
A SASAKI ◽  
A ITO ◽  
J AIZAWA ◽  
T UMITA
Keyword(s):  
Sediment Quality ◽  
Water And Sediment ◽  
Influence Of Water ◽  
Water And Sediment Quality

Deglacial changes in the strength of deep southern component water and sediment supply at the Argentine continental margin

2017 ◽  
Vol 32 (8) ◽  
pp. 796-812 ◽  
Author(s):  
Grit Warratz ◽  
Rüdiger Henrich ◽  
Ines Voigt ◽  
Cristiano M. Chiessi ◽  
Gerhard Kuhn ◽  
...  
Keyword(s):  
Continental Margin ◽  
Sediment Supply ◽  
Water And Sediment

scholarly journals Interactions between channels and tributary alluvial fans: channel adjustments and sediment-signal propagation

2019 ◽  
Author(s):  
Sara Savi ◽  
Stefanie Tofelde ◽  
Andrew D. Wickert ◽  
Aaron Bufe ◽  
Taylor F. Schildgen ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Signal Propagation ◽  
Main Channel ◽  
Alluvial Fan ◽  
Sediment Supply ◽  
Alluvial Fans ◽  
Fluvial System ◽  
Channel Network ◽  
Fluvial Deposits ◽  
The Impact

Abstract. Climate and tectonics impact water and sediment fluxes to fluvial systems. These boundary conditions set river form and can be recorded by fluvial deposits. Reconstructions of boundary conditions from these deposits, however, is complicated by complex channel-network interactions and associated sediment storage and release through the fluvial system. To address this challenge, we used a physical experiment to study the interplay between a main channel and a tributary under different forcing conditions. In particular, we investigated the impact of a single tributary junction, where sediment supply from the tributary can produce an alluvial fan, on channel geometries and associated sediment-transfer dynamics. We found that the presence of an alluvial fan may promote or prevent sediment to be moved within the fluvial system, creating different coupling conditions. A prograding alluvial fan, for example, has the potential to disrupt the sedimentary signal propagating downstream through the confluence zone. By analyzing different environmental scenarios, our results indicate the contribution of the two sub-systems to fluvial deposits, both upstream and downstream of the tributary junction, which may be diagnostic of a perturbation affecting the tributary or the main channel only. We summarize all findings in a new conceptual framework that illustrates the possible interactions between tributary alluvial fans and a main channel under different environmental conditions. This framework provides a better understanding of the composition and architecture of fluvial sedimentary deposits found at confluence zones, which is essential for a correct reconstruction of the climatic or tectonic history of a basin.

scholarly journals 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 ◽  
2015 ◽  
Vol 21 (2) ◽  
pp. 89-103 ◽  
Author(s):  
Barbara Woronko ◽  
Paweł Zieliński ◽  
Robert Jan Sokołowski
Keyword(s):  
Late Glacial ◽  
Sediment Supply ◽  
Alluvial Fans ◽  
Fluvial Sediments ◽  
Aeolian Processes ◽  
River Terraces ◽  
Climate Evolution ◽  
Quartz Grains ◽  
The Last Glacial

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.

scholarly journals Modeling the provenance of fine sediments in Parón Glacier Lake (Cordillera Blanca, Perú) by using a new procedure of tracer selection

2020 ◽  
Author(s):  
Ana Navas ◽  
Ivan Lizaga ◽  
Leticia Gaspar ◽  
Tim Stott ◽  
Bulat Mavlyudov ◽  
...  
Keyword(s):  
Suspended Sediments ◽  
Fine Sediment ◽  
Sediment Supply ◽  
Alluvial Fans ◽  
Lake Area ◽  
Cordillera Blanca ◽  
Sediment Samples ◽  
Fluvial Terraces ◽  
Tracer Selection ◽  
Glacial Landforms

<p>Climate warming in high altitude regions is causing rapid retreat of mountain glaciers that might likely accelerate in the near future. As much as 99 % of all tropical glaciers are in the Andes, of which approximately 70% concentrate in the Cordillera Blanca range (Perú) where Parón Lake is located at the foot of Artesonraju Glacier. In the last century the glacier surface area in the Cordillera Blanca has decreased by around one third. Melting glaciers is leading to the formation of new proglacial lakes that are increasing in number and volume playing a key role in regulating water storage and supply to glacier-fed rivers. Glacier recession results in changes in paraglacial environments where processes acting on new exposed surfaces of highly reactive rocks are highly dynamic. These processes can generate important amounts of sediments which can threaten water quality and biodiversity. Environmental concerns strengthen the need for assessing the provenance of fine sediment. To this end, in the frame of the IAEA INT5153 project a two week field survey of the Parón Lake area was carried out in October 2016 to recognize the main glacial landforms which had direct connectivity to the drainage system into the lake. The main glacial landforms, which included moraines, colluvium, glacio-fluvial terraces and alluvial fans that had developed after different stages of glacier retreat from the Last Glacial Maximum to the Little Ice Age, were mapped. For identifying the main provenance of sediments, a total of 40 composite soil and sediment samples (from 0-3cm depth) were collected as sources from representative sites on the main glacial landforms. In addition a total of 9 sediment mixtures including composite channel bed sediments and suspended sediments were collected. Channel bed mixtures were sampled along the river system between the tongue of Artesonraju Glacier and the end of Parón Lake while suspended sediment samples were also collected from the lake margin half way along its length. For applying fingerprinting methods we analysed 6 radioisotopes (2 FRNs and 4 ERNs) and a total of 28 stable elements. The preliminary unmixing results modeled with FingerPro after applying a novel procedure for tracer selection (Lizaga et al., 2020) identified different provenances in each of the sampled points depending on the proximity and connectivity of the glacial landforms. Moraines and alluvial terraces were main contributors in two of the channel mixtures while a relatively greater apportion from colluvium and alluvial fans was found in the lake sediment mixture located at the end of the Parón Lake. Unmixing results for the suspended sediments confirmed the higher contributions from glacio-fluvial terraces and colluvium in the middle part of the lake suggesting that the direct connectivity of glacial landforms was a key control of fine sediment supply to the lake. Further research is needed to assess changes of sediment sources during wet seasons or rainfall peaks in high water and flood regime to gain more comprehensive information on the temporal and climate variability of fine sediment supply.</p>

Late Quaternary landscape evolution and bioclimatic change in the central Great Plains, USA

2020 ◽  
Vol 132 (11-12) ◽  
pp. 2553-2571
Author(s):  
Anthony L. Layzell ◽  
Rolfe D. Mandel
Keyword(s):  
Great Plains ◽  
Landscape Evolution ◽  
Late Quaternary ◽  
Stable Carbon Isotope ◽  
Soil Formation ◽  
River Valley ◽  
Sediment Supply ◽  
Alluvial Fans ◽  
Buried Soils ◽  
South Central

Abstract A systematic study of floodplains, terraces, and alluvial fans in the Republican River valley of south-central Nebraska provided a well-dated, detailed reconstruction of late Quaternary landscape evolution and resolved outstanding issues related to previously proposed Holocene terrace sequences. Stable carbon isotope (δ13C) values determined on soil organic matter from buried soils in alluvial landforms were used to reconstruct the structure of vegetation communities and provided a means to investigate the relationships between bioclimatic change and fluvial activity for the period of record. Our study serves as a model for geomorphological and geoarcheological investigations in stream valleys throughout the central Great Plains and wherever loess-derived late Quaternary alluvial fans occur, in particular. Holocene alluvial landforms in the river valley include a broad floodplain complex (T-0a, T-0b, and T-0c), a single alluvial terrace (T-1), and alluvial fans that mostly grade to the T-1 (AF-1) and T-0c (AF-0c) surfaces. Remnants of a late Pleistocene terrace (T-2), mantled by Holocene (Bignell) loess, are also preserved, and some Holocene alluvial fans (AF-2) grade to T-2 surfaces. Radiocarbon ages suggest that the T-1 fill and AF-1 fans aggraded between ca. 9000–1000 yr B.P. Hence, nearly all of the Holocene alluvium in the river valley is stored in these landforms. Sedimentation, however, was interrupted by several periods of landscape stability and soil formation. Radiocarbon ages from the upper A horizons of buried soils in the T-1 and AF-1 fills, indicating approximate burial ages, cluster at ca. 6500, 4500, 3500, and 1000 yr B.P. Also, based on the radiocarbon ages, the T-0c fill and AF-0c fans were aggrading between ca. 2000–900 yr B.P. Given that the T-0c fill and upper parts of the T-1 fill were both aggrading after ca. 2000 yr B.P., we suggest that the T-1 surface was abandoned between ca. 4500–3500 yr B.P., but subsequent aggradation of both the T-1 and T-0c fills occurred due to large-magnitude flood events during the late Holocene. The δ13C data indicate a shift from ∼40% C4 biomass at ca. 6000 to ∼85% at ca. 4500 yr B.P. We propose a scenario where (1) a reduction in C3 vegetation after 6000 yr B.P. destabilized the uplands, resulting in an increase in sediment supply and aggradation of the T-1 fill and AF-1 fans, and (2) the establishment of C4 vegetation by ca. 4500 yr B.P. stabilized the uplands, resulting in a reduction in sediment supply and subsequent incision and abandonment of the T-1 and most AF-1 surfaces. The proposed timing and nature of landscape and bioclimatic change are consistent with regional records from the central Great Plains.

Quaternary paleoenvironmental change preserved in alluvial fans systems in semiarid to arid mountain areas: Examples from western Mongolia, western USA, and the Chilean Andes

2020 ◽  
Author(s):  
Frank Lehmkuhl ◽  
Veit Nottebaum ◽  
Janek Walk ◽  
Georg Stauch
Keyword(s):  
Late Quaternary ◽  
Alluvial Fan ◽  
Sediment Supply ◽  
Latitudinal Gradients ◽  
Alluvial Fans ◽  
Mountain Areas ◽  
Mountain Ranges ◽  
Western Mongolia ◽  
Semi Arid ◽  
Chilean Andes

<p>Alluvial fans represent complex landforms with the potential to record past environmental conditions. However, their decryption is difficult as their formation depends on a broad set of influences (catchment properties, climate, accommodation space, base level change). A comparison of alluvial fans in three (semi)arid regions aims to illuminate dominant controls on alluvial fan evolution.</p><p>Large scale alluvial fans in the semiarid to arid mountain areas of western Mongolia, southwestern USA, and the northern part of the Chilean Andes are controlled by different sediment supply. Geomorphological processes in these mountain ranges vary along altitudinal and latitudinal gradients and, additionally, due to climatic change during the late Quaternary. Alluvial fans in Mongolia (Gobi Altai and Mongolian Altai) are mainly formed during the Pleistocene. Higher terraces and alluvial fan generations can be dated to the penultimate glacial cycle. Sheet flow dominated as alluvial fan constructing process during the last Glacial. Since the late Glacial, debris flow accumulation and Holocene incision occurred (Lehmkuhl et al. 2018). Quaternary alluvial fans in mountain areas of the southwestern United States develop in three major settings related to the availability and nature of sediment transport. These include alluvial fans that develop in: i) glaciofluvial settings, ii) areas of tectonic uplift, and iii) regions dominated by periglacial processes. There is evidence for Pleistocene periglacial activity throughout the mountain ranges of the American Southwest in different elevations (Löhrer, 2008). Frost weathering in periods of higher moisture produces debris in the catchment areas and, thus, primarily governs the sediment supply of alluvial fans during the Pleistocene. In the semiarid Andes of northern Chile, alluvial fans form in similar glaciofluvial as well as fluvial settings in elevations above ~4000 m asl.</p><p>A comparison between these three (semi)arid systems shows that the main fluvial activity occurred during cold and semihumid phases of the Pleistocene resulting in an altitudinal lowering of periglacial processes, thus leading to a higher sediment supply. In addition, in all these regions higher lake levels occurred during the transition from glacial to interglacial periods, e.g. from the Pleistocene to the Holocene. Moister conditions during the transitions control the interplay between lake level variations and the fluvial activity.</p><p>Lehmkuhl, F., Nottebaum, V., Hülle, D. (2018): Aspects of late Quaternary geomorphological development in the Khangai Mountains and the Gobi Altai Mountains (Mongolia). Geomorphology 312:24-39. https://doi.org/10.1016/j.geomorph.2018.03.029</p><p>Löhrer, R. (2008): Reliefanalyse an Schwemmfächern und Fußflächen Südwesten der USA. Dissertation an der Fakultät für Georessourcen und Materialtechnik der RWTH Aachen, September 2008. Online Veröffentlichung der RWTH Aachen: http://darwin.bth.rwth-aachen.de/opus3/volltexte/2008/2504/</p>

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