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Hydrogeochemistry of the upper Hunter River Valley, New South Wales

The chemistry of groundwater in the regional recharge zones of Triassic and Carboniferous rocks in the upper Hunter River valley of New South Wales is strongly influenced by silicate and carbonate dissolution/precipitation reactions, ion exchange and the dispersion of aerosols in infiltrated rainfall. The Wollombi Coal Measures and Jerrys Plains Subgroup of the Wittingham Coal Measures west of the Muswellbrook Anticline constitute the regional groundwater transmission zones, and the processes having the greatest influence on the chemistry of their water are dissolution/precipitation reactions and oxidation of coals. The semi-confined aquifers of the Greta Coal Measures, Maitland Group, Dalwood Group, and Wittingham Coal Measures in the eastern and southern parts of the valley discharge into unconfined sand and gravel aquifers of the Hunter River floodplain. These Permian rocks are the source of the most saline water in the valley, and the chemistry of their groundwater is largely determined by oxidation of sulphides and molecular diffusion of connate marine salts, a legacy of periodic immersion by Permian ocean water. Disequilibrium indices for calcite, dolomite and dawsonite indicate that these carbonates are being precipitated today in the groundwater of the Central Lowlands provinces; they are being dissolved in the southern and western groundwater recharge zones and are in equilibrium with water of the northern recharge zone. The iron carbonates, siderite and ankerite, are a product of a palaeohydrochemical regime characterised by saline alkaline water rich in dissolved iron disseminated from gels originally accumulated in the Permian peat swamps, but these minerals are not being precipitated in modern upper Hunter River valley groundwater. The sulphate minerals, gypsum, thenardite and bloedite, occur extensively in salt efflorescences in the Permian rocks of the Central Lowlands, but their disequilibrium indices show that none of the minerals can be precipitated in the contemporary upper Hunter River valley groundwater by processes other than evaporative concentration. Models based on incongruent dissolution of feldspars allocate much of the upper Hunter River valley groundwater to the kaolinite stability field, which is consistent with the abundance of kaolinite as an authigenic mineral in the fractured rock aquifers. Silica and cations leached from the fractured rocks are accumulating in the groundwater sinks around the margins of the Hunter River floodplain, as indicated by the large proportion of groundwater in these areas which are in equilibrium with Ca-montmorillonite. Concentrations of C a 2 + , S i 0 2 and H C 0 3 ions in upper Hunter River valley groundwater approach log-normal distributions and these species are most highly identified with continental hydrochemical processes. In contrast, the four 'elements' constituting the bulk of solutes in ocean water, CI", N a + , SOj" and Mg2 + , are distributed in two modes: the low-concentration primary mode, representing the dissemination of these species from the continental solutes store, and the secondary high-concentration mode, reflecting diffusion and oxidation of marine inputs. On a province-wide scale, composition diagrams of solute behaviour identify the Wittingham Coal Measures to the east and south of Muswellbrook Anticline, the Greta Coal Measures, and the Maitland and Dalwood Groups as systems that can be approximated by simple linear mixing models between meteoric and oceanic water. Composition diagrams for the floodplain hydrochemical provinces show that the alluvial aquifers can be represented as mixing systems between Hunter River surface water and groundwater of the fractured-rock aquifers. Principal component analyses describe the chemical evolution of upper Hunter groundwater from the Permian marine transgression through to the present continental leaching regime for similar positions along flow lines in discharge zones, groundwater of the Greta C

Simple

Identification info

Date (Publication)
1989-01-01T00:00:00
Citation identifier
Geoscience Australia Persistent Identifier/https://pid.geoscience.gov.au/dataset/ga/25

Cited responsible party
Role Organisation / Individual Name Details
Publisher

Bureau of Mineral Resources, Geology and Geophysics

Canberra
Author

Kellett, J.R.

1
Author

Williams, B.G.

2
Author

Ward, J.K.

3
Name

Bulletin

Issue identification

221

ISBN

0644088621

Point of contact
Role Organisation / Individual Name Details
Custodian

Corp

Owner

Commonwealth of Australia (Geoscience Australia)

Custodian

Commonwealth of Australia (Geoscience Australia)

Voice

Spatial resolution

Equivalent scale

Denominator
100000
Topic category
  • Geoscientific information

Extent

N
S
E
W


Maintenance and update frequency
Unknown

Resource format

Title

Product data repository: Various Formats

Website

Data Store directory containing the digital product files

Data Store directory containing one or more files, possibly in a variety of formats, accessible to Geoscience Australia staff only for internal purposes

Keywords
  • GA Publication

  • Bulletin

Theme
  • hydrogeology

Theme
  • geochemistry

Keywords
  • AU-NSW

Australian and New Zealand Standard Research Classification (ANZSRC)
  • Earth Sciences

Keywords
  • Published_External

Resource constraints

Title

Creative Commons Attribution 4.0 International Licence

Alternate title

CC-BY

Edition

4.0

Website

http://creativecommons.org/licenses/

Access constraints
License
Use constraints
License

Resource constraints

Title

Australian Government Security ClassificationSystem

Edition date
2018-11-01T00:00:00
Website

https://www.protectivesecurity.gov.au/Pages/default.aspx

Classification
Unclassified
Language
English
Character encoding
UTF8

Distribution Information

Distributor contact
Role Organisation / Individual Name Details
Distributor

Commonwealth of Australia (Geoscience Australia)

Voice
OnLine resource

Download the Bulletin (pdf)

Download the Bulletin (pdf)

Distribution format
  • pdf

Resource lineage

Statement

Unknown

Hierarchy level
Non geographic dataset
Other

GA Publication

Description

Source data not available.

Metadata constraints

Title

Australian Government Security ClassificationSystem

Edition date
2018-11-01T00:00:00
Website

https://www.protectivesecurity.gov.au/Pages/default.aspx

Classification
Unclassified

Metadata

Metadata identifier
urn:uuid/a05f7892-b2fa-7506-e044-00144fdd4fa6

Title

GeoNetwork UUID

Language
English
Character encoding
UTF8
Contact
Role Organisation / Individual Name Details
Point of contact

Commonwealth of Australia (Geoscience Australia)

Voice

Type of resource

Resource scope
Document
Name

Legacy AGSO BMR Bulletins

Alternative metadata reference

Title

Geoscience Australia - short identifier for metadata record with

uuid

Citation identifier
eCatId/25

Metadata linkage

https://ecat.ga.gov.au/geonetwork/srv/eng/catalog.search#/metadata/a05f7892-b2fa-7506-e044-00144fdd4fa6

Date info (Revision)
2018-04-20T06:04:52
Date info (Creation)
1996-10-29T00:00:00

Metadata standard

Title

AU/NZS ISO 19115-1:2014

Metadata standard

Title

ISO 19115-1:2014

Metadata standard

Title

ISO 19115-3

Title

Geoscience Australia Community Metadata Profile of ISO 19115-1:2014

Edition

Version 2.0, September 2018

Citation identifier
https://pid.geoscience.gov.au/dataset/ga/122551

 
 

Spatial extent

N
S
E
W


Keywords

geochemistry hydrogeology

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