Anastomosing river sedimentation in the Channel Country of central Australia

Gibling, Martin R. and Nanson, Gerald C. and Maroulis, Jerry C. (1998) Anastomosing river sedimentation in the Channel Country of central Australia. Sedimentology, 45 (3). pp. 595-619. ISSN 0037-0746

Abstract

Anastomosing river plains of the Channel Country, central Australia, have aggraded slowly over the past 100 ka. Channel sediments accumulate mainly as accretionary benches of mud and sand, sandy channel-base sheets and vegetation-shadow deposits. The channels are laterally stable and the sediments have aggraded locally against erosional banks of tough floodplain muds. Channel sediments are profoundly affected by desiccation during dry periods and by bioturbation caused by within-channel trees and burrowing invertebrates, especially crayfish. Excavations show that mud-dominated channel bodies of low width:thickness ratio are generated by a combination of vertical and lateral accretion. Levees and braided surfaces, composed mainly of mud aggregates, border the channels and are activated during valley-wide floods which lay down distal mud sheets. Floodplain muds are converted to vertisols with gilgai, deep desiccation cracks, and impregnations of carbonate and gypsum. A fixed-channel facies model is applicable to the Channel Country river deposits. Anastomosis apparently results from the need for the system to move large volumes of water and moderate sediment loads across low-gradient interior basins. Channels distant from upland source areas receive an abundant supply of pedogenic, sand-sized mud aggregates generated on adjacent floodplains and reworked into braid bars during valley-wide floods. Some quartz sand is provided from excavation of subsurface Pleistocene sands in deep channels and waterholes and from aeolian dunes on the floodplains. Adjacent gibber plains supply some gravel to the system.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Permanent restricted access to published version due to publisher copyright policy.
Depositing User: Assoc Prof Jerry Maroulis
Faculty / Department / School: Current - USQ Other
Date Deposited: 30 Nov 2007 11:47
Last Modified: 03 Jul 2013 00:18
Uncontrolled Keywords: rivers; channel sediments; river plains
Fields of Research (FOR2008): 04 Earth Sciences > 0406 Physical Geography and Environmental Geoscience > 040607 Surface Processes
04 Earth Sciences > 0403 Geology > 040310 Sedimentology
05 Environmental Sciences > 0502 Environmental Science and Management > 050206 Environmental Monitoring
Socio-Economic Objective (SEO2008): D Environment > 96 Environment > 9611 Physical and Chemical Conditions of Water > 961103 Physical and Chemical Conditions of Water in Fresh, Ground and Surface Water Environments (excl. Urban and Industrial Use)
Identification Number or DOI: doi: 10.1046/j.1365-3091.1998.00163.x
URI: http://eprints.usq.edu.au/id/eprint/13725

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