Authors / CoAuthors
Feitz, A.J.
Abstract
The Walloon Coal Measures (WCM) in the Clarence-Moreton and the Surat basins in Qld and northern NSW contain up to approximately 600 m of mudstone, siltstone, sandstone and coal. Wide-spread exploration for coal seam gas (CSG) within both basins has led to concerns that the depressurisation associated with the resource development may impact on water resources in adjacent aquifers. In order to predict potential impacts, a detailed understanding of sedimentary basins hydrodynamics that integrates geology, hydrochemistry and environmental tracers is important. In this study, we show how different hydrochemical parameters and isotopic tracers (i.e. major ion chemistry, dissolved gas concentrations, 13C-DIC, 18O, 87Sr/86Sr, 3H, 14C, 2H and 13C of CH4) can help to improve the knowledge on groundwater recharge and flow patterns within the coal-bearing strata and their connectivity with over- or underlying formations. Dissolved methane concentrations in groundwaters of the WCM in the Clarence-Moreton Basin range from below the reporting limit (10 µg/L) to approximately 50 mg/L, and samples collected from nested bore sites show that there is also a high degree of vertical variability. Other parameters such as groundwater age measurements collected along distinct flow paths are also highly variable. In contrast, 87Sr/86Sr isotope ratios of WCM groundwaters are very uniform and distinct from groundwaters contained in other sedimentary bedrock units, suggesting that 87Sr/86Sr ratios may be a suitable tracer to study hydraulic connectivity of the Walloon Coal Measures with over- or underlying aquifers, although more studies on the systematic are required. Overall, the complexity of recharge processes, aquifer connectivity and within-formation variability confirms that a single tracer that cannot provide all information necessary to understand aquifer connectivity in these sedimentary basins, but that a multi-tracer approach is required.
Product Type
nonGeographicDataset
eCat Id
83707
Contact for the resource
Custodian
Owner
Custodian
Locked Bag 10 None
Clayton South
VIC
3169
Australia
Point of contact
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
Keywords
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- External PublicationAbstract
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- QLD
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Geochemistry
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- Published_Internal
Publication Date
2015-01-01T00:00:00
Creation Date
Security Constraints
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Special, MOU, etc.
Access - license
Use - license
Status
Purpose
Maintenance Information
asNeeded
Topic Category
environment
Series Information
Lineage
Unknown
Parent Information
Extents
[-27.0, -26.5, 150.5, 151.0]
Reference System
Spatial Resolution
Service Information
Associations
Downloads and Links
Source Information
Australian Groundwater Conference 2015