Authors / CoAuthors
Clarke, J.D.A. | Macphail, M. | Gibson, D.L. | Brodie, R.S. | Somerville, P.
Abstract
The upper Renmark Group is a widespread non-marine succession of Miocene age in the Murray Basin. Unlithified and nowhere exposed, it is a poorly understood unit that provides a lower confining horizon to important aquifers in the overlying Calivil succession, and includes deeper aquifers exploited for water for mineral sands mining. The use of sonic drilling has allowed extensive coring of the previously poorly sampled unit, documentation of its facies and collection of a diverse assemblage of spores and pollen. The upper Renmark Group was deposited on a low relief sedimentary plain dominated by anastomosing fixed channel streams, flowing southward into a complex low energy coastal plain with numerous lagoons and bays. Hydrological connection between the more (Renmark) and less saline (Calivil) aquifers is low, except where Renmark channel sands immediately underlie the Calivil. In these areas can be a distinct salinity gradient from the Calivil down into the Renmark, indicating mixing. High water tables during deposition facilitated preservation of an unusually detailed record of inland Australian vegetation from this period. Late Early to Middle Miocene climates were wet and warm with low seasonality. These conditions supported complex rainforest communities dominated by (1) Nothofagus (Brassospora) spp. and gymnosperms on floodplains inland of the palaeoshoreline, or (2) Myrtaceae (Syzygium-type) and unidentified mangrove angiosperms in areas subjected to a marine influence. Many of the latter pollen types are very small (<10 micron diameter), resulting in the 10 micron-filtered extracts being dominated by larger types such as Casuarinaceae and Nothofagus (Brassospora) spp.
Product Type
nonGeographicDataset
eCat Id
73651
Contact for the resource
Custodian
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Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
Keywords
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- GA PublicationAbstract
- ( Theme )
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- groundwater
- ( Theme )
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- hydrogeology
- ( Theme )
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- geomorphology
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
Publication Date
2012-01-01T00:00:00
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geoscientificInformation
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[-33.162746, -31.811454, 141.95136, 143.313725]
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