3D Mapping of Quaternary Fluvial Landscapes to Constrain Models of Surface-Groundwater Interaction in the Lower Darling Valley, N.S.W., Australia.  

Authors / CoAuthors

Magee, J. | Tan, K.P. | Gibson, D. | Halas, L. | Lawrie, K. | Clarke, J. | Pain, C.

Abstract

Poster prepared for International Association of Hydrogeologists Congress 2013 In this study, a multi-disciplinary systems mapping approach has completely revised our understanding of the age, stratigraphy, mode of deposition and landscape evolution of Lower Darling Valley (LDV) sediments within the north-western Murray Basin. The Cenozoic sequence in this area contains Paleogene and Neogene shallow marine, fluvial and shoreline sediments overlain by Quaternary lacustrine, aeolian and fluvial units. The surficial Quaternary fluvial units of the valley form a complex group of morphostratigraphic units which vary in their distribution, character and geomorphic expression through the study area. Resolving the distribution of these units has been particularly important for understanding surface-groundwater interactions. In the LDV Quaternary fluvial sequence, multiple scroll-plain tracts are incised into higher, older more featureless floodplains. Prior to this study, these were respectively correlated to the Coonambidgal and Shepparton Formations of the Riverine Plain in the eastern Murray Basin and associated with the subsequently discarded Prior Stream/Ancestral River chronosequence of different climatically controlled depositional styles. In contrast to that proposition, we ascribe all LDV Quaternary fluvial deposition to lateral-migration depositional phases of one style, though with more variable stream discharges and channel and meander-scroll dimensions. Successively higher overbank-mud deposition through time obscures scroll traces and provides the main ongoing morphologic difference. A new morphostratigraphic unit, the Menindee Formation, refers to the mostly older and higher floodplain sediments, where scroll traces are obscured by overbank mud which continues to be deposited by the highest modern floods. Younger inset scroll-plain tracts, with visible scroll-plain traces, are still referred to the Coonambidgal Formation. Another new stratigraphic unit, the Willotia beds, refers to even older fluvial sediments, now above modern floodplain levels and mostly covered by aeolian sediments. This work provides important insights into the nature of Australian Quaternary fluvial deposition, with important implications for hydrogeological processes, groundwater resources and the assessment of managed aquifer recharge options.

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nonGeographicDataset

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77128

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• GA PublicationPoster/Image

( Theme )

• hydrogeology

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• groundwater

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• mapping

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• Hydrogeology

• Published_Internal

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2013-01-01T00:00:00

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Poster prepared for International Association of Hydrogeologists Congress 2013

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