Floodplain Aggradation as a Dominant Control on Autocyclic Switching of Low-gradient Dryland Rivers in Endorheic Basins

Koen van Toorenenburg, Rick Donselaar, GJ Weltje

Research output: Contribution to conferenceAbstractScientific

Abstract

Floodplain shales are abundant in the distal part of dryland fluvial fans fringing endorheic basins, such as the Río Colorado fluvial system in Bolivia. In a low-gradient coastal plain, lowstand progradation of a fluvial system creates accommodation space. Long periods of low-flow stage only support a single channel, decreasing in capacity downstream. Flooding during short episodes of peak runoff results in massive overbank deposition and aggradation of the floodplain around the active channel. Assuming a constant flow capacity, this is mirrored by an elevation of the channel floor, combining to form an elongated lobe of up to several kilometres in width. Distributary channels within crevasse splays develop reflux phenomena, effectively decreasing the flow capacity of their parent channel. This, combined with the decreased gradient of the active channel profile, causes an upstream increase in avulsion proneness and is a dominant control on the autocyclic switching of channel belts in a process of large-scale compensational stacking. The resulting stratigraphy is heterogeneous and may have tough gas reservoir potential.
Original languageEnglish
Number of pages5
DOIs
Publication statusPublished - 2016
Event5th EAGE Shale Workshop: Quantifying Risk and Potential - Romano Palace Hotel, Catania, Italy
Duration: 2 May 20164 May 2016
Conference number: 5

Workshop

Workshop5th EAGE Shale Workshop
CountryItaly
CityCatania
Period2/05/164/05/16

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