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Groundwater-discharge playas of the Mallee region, Murray Basin, Southeast Australia

Gerry Jacobson, James Ferguson and W. Ray Evans
Groundwater-discharge playas of the Mallee region, Murray Basin, Southeast Australia (in Paleoclimate and basin evolution of playa systems, Michael R. Rosen (editor))
Special Paper - Geological Society of America (1994) 289: 81-96


Groundwater discharge complexes, locally known as boinkas, are a distinctive feature of the Mallee region, the western sector of the Murray Basin (300,000 km (super 2) ) in southeast Australia. The discharge complexes are nested, with modern playas (salinas) set in late Pleistocene playa sediments and associated aeolian deposits. Playa evolution started with the onset of aridity in the mid-Pleistocene. In the Murray Basin, groundwater discharges, and has discharged in the past, to topo-graphically low parts of the landscape,, including the Murray River itself. The fundamental control on the distribution of the discharge complexes is the presence of subsurface permeability barriers, which are tectonically or stratigraphically controlled, and which disrupt lateral groundwater flow. With the general absence of surface drainage in the Mallee region, the location of the topographic lows is probably influenced by differential compaction of sediments. Within the modern salinas, brine is generated by evaporative concentration and resolution of salts. The structure of some of the investigated brine pools suggests that density instability leads to brine fingering, sinking, and mixing with regional groundwaters. This process is facilitated by more permeable sediments. "Fossil" brines generated by the late Pleistocene playas can be identified and have contributed to the salinity of the regional unconfined aquifer. Brine pools have migrated in time and space in response to climatic change. This has practical implications for the long-term containment of saline wastewaters, which is a serious problem in the Murray Basin.

ISSN: 0072-1077
EISSN: 2331-219X
Serial Title: Special Paper - Geological Society of America
Serial Volume: 289
Title: Groundwater-discharge playas of the Mallee region, Murray Basin, Southeast Australia
Title: Paleoclimate and basin evolution of playa systems
Author(s): Jacobson, GerryFerguson, JamesEvans, W. Ray
Author(s): Rosen, Michael R.editor
Affiliation: Australian Geological Survey Organisation, Canberra, Australia
Affiliation: University of Minnesota, Limnological Research Center, Minneapolis, MN, United States
Pages: 81-96
Published: 1994
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 28
Accession Number: 1994-026175
Categories: Hydrogeology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 plates, 1 table, geol. sketch maps
S38°00'00" - S32°00'00", E140°00'00" - E146°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 199412
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