Using airborne electromagnetics and digital elevations models, validated by drilling data, to map neotectonic features and seismic hazard potential in buried floodplain landscapes of the Darling floodplain, western NSW, Australia  

Authors / CoAuthors

Gibson, D.L. | Apps, H.E. | Lawrie, K.C.

Abstract

Identification of neotectonic features in Australia's interior is challenging with a lack of outcrop, and a subtlety in surface expression that is only recently being detected using high resolution surface elevation mapping methods. Many more geologically-recent tectonic features are completely buried with no present-day surface expression. In this study, airborne electromagnetics (AEM) and high resolution LiDAR datasets were acquired as part of 3D mapping of the hydrogeology in the Darling Floodplain. Neotectonic faulting and uplift has previously been described in the Broken Hill area, and along the north-western margin of the Murray Basin, along the Darling Lineament. The AEM data (acquired over an area of 7,500 sq km), validated by 100 new boreholes, reveal that an important Pleistocene aquitard (Blanchetown Clay) confining the main aquifer of interest (Calivil Formation), has an undulating surface, which is locally sharply offset. Gridding of the interpreted top surface suggests that it has been affected by local warping and faulting, as well as regional tilting due to basin subsidence or margin uplift. Some of the up-warped areas are associated with local landscape highs, suggesting relatively recent movement. Overall, the top surface of the Blanchetown Clay varies in elevation by 60m, with important implications for groundwater flow and recharge dynamics. This study also illustrates that the zone of tectonic activity can be extended southeast from the Broken Hill area to the Darling Floodplain, and that the area of seismic hazard associated with the Darling Lineament may be broader than previously anticipated.

Product Type

nonGeographicDataset

eCat Id

73641

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Keywords

• GA PublicationAbstract

( Theme )

• hydrogeology

( Theme )

• AEM

Australian and New Zealand Standard Research Classification (ANZSRC)

• Earth Sciences

• Published_Internal

Publication Date

2012-01-01T00:00:00

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Australian Government Security ClassificationSystem    

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Creative Commons Attribution 4.0 International Licence    

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geoscientificInformation

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[-33.159278, -31.814781, 141.958071, 143.284724]

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