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Variability of channel-belt dimensions and the consequences for alluvial architecture; observations from the Holocene Rhine-Meuse Delta (the Netherlands) and Lower Mississippi Valley (U.S.A.)

Marc J. P. Gouw and Henk J. A. Berendsen
Variability of channel-belt dimensions and the consequences for alluvial architecture; observations from the Holocene Rhine-Meuse Delta (the Netherlands) and Lower Mississippi Valley (U.S.A.)
Journal of Sedimentary Research (February 2007) 77 (2): 124-138

Abstract

Over the past decades, many studies have focused on the dimensions of channel-belt sand bodies (referred to as "channel belts") in fluvial deposits because of their relevance for hydrocarbon exploration and production. Some field studies have revealed a significant downstream decrease of channel-belt width and width/thickness ratio along the length of the channel belt. To verify whether this is a common feature in fluviodeltaic settings, eight Holocene channel belts in the Rhine-Meuse delta (The Netherlands) were selected and one in the Lower Mississippi Valley (U.S.A.). We determined channel-belt geometry (width or width/thickness ratio) using geological-geomorphological maps and detailed cross sections based on borings. It was found that the width of channel belts encased in cohesive deposits decreases by a factor of 4 to 6.5 in a downstream direction along the length of the channel belts. The width/thickness ratio decreases by a factor of 2.5 to 5. On the other hand, the width of a channel belt incised in a noncohesive substrate remains constant along its entire course. These observations are related to longitudinal changes in bank credibility and stream power. It is suggested that bank credibility is the dominating factor determining the geometric properties of channel belts, and the variability therein, at least in the Rhine-Meuse delta. The currently available alluvial-architecture models most likely overestimate sand quantities and connectedness in alluvial successions, because channel-belt dimensions are held constant in all models. We therefore propose that the factors "bank credibility" and "stream power," which influence width and width/thickness ratio of channel belts, should be incorporated in future alluvial-architecture models in order to make more realistic estimates of sand quantities in river deltas.


ISSN: 1527-1404
EISSN: 1938-3681
Serial Title: Journal of Sedimentary Research
Serial Volume: 77
Serial Issue: 2
Title: Variability of channel-belt dimensions and the consequences for alluvial architecture; observations from the Holocene Rhine-Meuse Delta (the Netherlands) and Lower Mississippi Valley (U.S.A.)
Affiliation: Utrecht University, Department of Physical Geography, Utrecht, Netherlands
Pages: 124-138
Published: 200702
Text Language: English
Publisher: Society for Sedimentary Geology, Tulsa, OK, United States
References: 50
Accession Number: 2007-029036
Categories: Quaternary geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sects., 3 tables, geol. sketch map
N51°40'00" - N52°00'00", E04°00'00" - E05°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 200716
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