Influence of organics and clastic lake fills on distributary channel processes in the distal Rhine-Meuse delta (The Netherlands)
article
Organic-clastic lake fills, which include lacustrine deltas, are prominent architectural elements in the distal zone of delta plains. We hypothesize that lakes and fossil lake fills affect the development of a fluvial distributary channel. To test this hypothesis, a Holocene palaeogeographic reconstruction is presented of the Angstel-Vecht area, The Netherlands based on a geomorphogenetic map, lithogenetic cross sections, microfossil analyses, and various dating methods (i.e. 14C-dating, OSL dating, pollen analyses and archaeological evidence). We found that peat accumulation on the Pleistocene substratum started ~ 8000 cal yr BP in response to base-level driven groundwater-level rise. Peat-bounded lakes existed in which gyttja was formed. Fluvial sedimentation in the study area commenced when a new Rhine distributary - the Angstel-Vecht - formed ~ 2970 cal yr BP. As a result, the lakes were filled with fluvially supplied clastic material. Fluvial activity diminished after ~ 2300 cal yr BP although the system continued to function as a high-discharge spillway for Rhine distributaries. This study illustrates the influence of lakes and lake fills on fluvial architecture and sedimentology. Downstream of a lake, levee deposits are thin compared to upstream reaches and the channel-belt sediment is clayey. Furthermore, channels maintain a meandering pattern when organic-clastic lake fills form the substrate because of the relative low bank stability. This is in contrast to straight channels in the distal delta plains that are influenced by erosion-resistant peat substrate. © 2009 Elsevier B.V. All rights reserved.
Topics
Channel planformDelta depositsDelta plainHoloceneLake depositsNatural levee thicknesschannel changechannel morphologydating methoddeltadrainage basinfillHolocenehypothesis testinglacustrine depositleveemeanderorganic matterpaleochannelpaleogeographypaleohydrologypalynologypeatpelagic deposittidal flatBeneluxEurasiaEuropeNetherlandsRhine-Meuse DeltaWestern Europe
TNO Identifier
954027
ISSN
00310182
Source
Palaeogeography, Palaeoclimatology, Palaeoecology, 284(3-4), pp. 355-374.
Pages
355-374
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