Autogenic attainment of large-scale alluvial grade with steady sea-level fall: An analog tank-flume experiment

Abstract

Research Article| March 01, 2006 Autogenic attainment of large-scale alluvial grade with steady sea-level fall: An analog tank-flume experiment Tetsuji Muto; Tetsuji Muto 1Faculty of Environmental Studies, Nagasaki University, Nagasaki 852-8521, Japan Search for other works by this author on: GSW Google Scholar John B. Swenson John B. Swenson 2Department of Geological Sciences and Large Lakes Observatory, University of Minnesota, Duluth, Minnesota 55812, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Tetsuji Muto 1Faculty of Environmental Studies, Nagasaki University, Nagasaki 852-8521, Japan John B. Swenson 2Department of Geological Sciences and Large Lakes Observatory, University of Minnesota, Duluth, Minnesota 55812, USA Publisher: Geological Society of America Received: 03 Jun 2005 Revision Received: 03 Nov 2005 Accepted: 09 Nov 2005 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2006) 34 (3): 161–164. https://doi.org/10.1130/G21923.1 Article history Received: 03 Jun 2005 Revision Received: 03 Nov 2005 Accepted: 09 Nov 2005 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Tetsuji Muto, John B. Swenson; Autogenic attainment of large-scale alluvial grade with steady sea-level fall: An analog tank-flume experiment. Geology 2006;; 34 (3): 161–164. doi: https://doi.org/10.1130/G21923.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract A graded river conveys its sediment load without net deposition or erosion. The graded state is thought to represent the long-term response of alluvial rivers to steady external forcing. We show here that alluvial rivers building deltas can be in grade as an autogenic response to steady sea-level fall. Consider an antecedent graded river profile, the upstream end of which consists of an alluvial-bedrock transition, and the downstream end of which is a fixed overfall where constant sea level is maintained. The antecedent graded profile is then drowned by a jump in sea level, after which sea level drops. The result is a new river profile ending in a prograding delta that deposits on top of the antecedent profile. If the rate of sea-level fall is constant and the length of the antecedent reach is sufficient, the new profile eventually becomes parallel or quasi-parallel to the antecedent profile, maintaining grade as it progrades. In the experiments reported here, series of graded river profiles with prograding deltas are created by stacking fluviodeltaic systems; each graded profile and its associated delta is stacked on its immediate predecessor. For each fluviodeltaic system, a graded alluvial profile is attained with any constant rate of sea-level fall, provided that the antecedent profile is of sufficient length. Experiments suggest that this autogenic approach to grade is more rapid for higher rates of sea-level fall, lower rates of sediment supply, and higher water discharges. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.