FIELD GUIDE FOR MINERAL EXPLORATION USING HYDROGEOCHEMICAL ...

FIELD GUIDE FOR MINERALEXPLORATION USING

HYDROGEOCHEMICAL ANALYSIS

David Gray, Ryan Noble and Alan Gill

CRCLEME

L Eandscape nvironments

and ineral xplorat ionM E

Cooperative Research Centre for

MDU Flagship Exploration and Technology Guide

iHydrogeochemical analysis: Field Guide

© This report is the copyright of the Commonwealth Scientific and Industrial Research Organisation (CSIRO).

Apart from any fair dealing for the purpose of private study, research, criticism or review, as permitted

under Copyright Act, no part may be reproduced or reused by any process whatsoever, without prior

written approval from CSIRO.

Reference:

Noble, R.R.P., Gray, D.J. & Gill, A.J. 2011. Field guide for mineral exploration using hydrogeochemical analysis.

1. Mineral exploration 2. Geochemistry 3. Groundwater

Epublish Report Number: EP113936

ISBN: 9780643107182

Publisher: CSIRO Earth Science and Resource Engineering, PO Box 1130, Bentley, WA 6102

Editor: Alan Gill

Copy editors: David Gray, Ryan Noble and Indra Tomic

Series editor: Ryan Noble

Transmogrify and design: Travis Naughton and Angelo Vartesi, CSIRO Creative Services Western Australia.

Correspondence:David Gray

CSIRO Earth Science and Resource Engineering

Australian Resources Research Centre

26 Dick Perry Avenue

Kensington WA 6151

[email protected]

Disclaimer: The user accepts all risks and responsibility for losses, damages, costs and other consequences

resulting directly or indirectly from using any information or material contained in this report. To the

maximum permitted by law, CSIRO excludes all liability to any person arising directly or indirectly from

using any information or material contained in this report.

ii Hydrogeochemical analysis: Field Guide

iiiHydrogeochemical analysis: Field Guide

CONTENTS

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.1 Field guide purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 Location and physical setting . . . . . . . . . . . . . . . . . . . . . . . 21.3 Exploration targets . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2. Overview: Mineral exploration using hydrogeochemical analysis . . . 3

2.1 Background. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.2 Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.3 Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3. Groundwater sources . . . . . . . . . . . . . . . . . . . . . . . . 5

3.1 Windmills and wells . . . . . . . . . . . . . . . . . . . . . . . . . . . 63.2 Bores/drill holes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4. Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

4.1 Water collection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74.2 Sample storage and filtration. . . . . . . . . . . . . . . . . . . . . . . 74.3 Field measurement equipment. . . . . . . . . . . . . . . . . . . . . 104.4 Field measurement chemicals . . . . . . . . . . . . . . . . . . . . . 104.5 Carbon sachets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

5. Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

5.1 Planning the study . . . . . . . . . . . . . . . . . . . . . . . . . . . 135.2 Site investigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135.3 Prepare equipment and filtration unit . . . . . . . . . . . . . . . . . 135.4 Prepare and label bottles. . . . . . . . . . . . . . . . . . . . . . . . 145.5 Sample groundwater . . . . . . . . . . . . . . . . . . . . . . . . . . 145.6 Chemical analysis in the field. . . . . . . . . . . . . . . . . . . . . . 145.7 Filtered sample collection . . . . . . . . . . . . . . . . . . . . . . . 155.8 Unfiltered sample collection . . . . . . . . . . . . . . . . . . . . . . 15

6. Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

6.1 Anion analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176.2 Alkalinity analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

iv Hydrogeochemical analysis: Field Guide

6.3 Cation analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186.4 Gold/Platinum group elements analysis . . . . . . . . . . . . . . . . 196.5 Mapping and interpreting results . . . . . . . . . . . . . . . . . . . . 19

7. Case Study 1: Harmony gold deposit . . . . . . . . . . . . . . . . . 21

7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217.2 Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217.3 Regolith characteristics . . . . . . . . . . . . . . . . . . . . . . . . . 217.4 Groundwater depth and chemistry . . . . . . . . . . . . . . . . . . 227.5 Sample results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

8. Case study 2: Groundwater Uranium from farm wells and bores . . 25


9. Case Study 3: Groundwater for nickel sulfide exploration . . . . . . 31


10. Quick reference guides . . . . . . . . . . . . . . . . . . . . . . . 37

10.1 Standard Abbreviations For Sampling. . . . . . . . . . . . . . . . . 3710.2 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3710.3 General sampling and testing methods flowchart . . . . . . . . . . 38

vHydrogeochemical analysis: Field Guide

11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . 39

12. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

13. Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

13.1 Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4513.2 Elements/Compounds . . . . . . . . . . . . . . . . . . . . . . . . 4613.3 Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

vi Hydrogeochemical analysis: Field Guide

1Hydrogeochemical analysis: Field Guide

1. INTRODUCTION

1.1 Field guide purpose

This Field Guide is designed to assist exploration geologists in using hydrogeochemistry for mineral exploration. Primarily presenting the work of Dr David Gray, Dr Ryan Noble and others from CSIRO’s Minerals Down Under National Research Flagship, this Guide outlines the materials, methods and analytical techniques to enable any exploration geologist to use this method. Case studies are presented to give an example of how this exploration method can be applied.

> Figure 1: Groundwater salinity in Australia (from Jacobson and Lau, 1987)

2 Hydrogeochemical analysis: Field Guide

1.2 Location and physical setting

Groundwater exists across most of Australia, making this method applicable in almost every region. Due to changes in groundwater salinity, this method can become less effective due to analytical limitations. Most of the southern fifth of Australia, for example, has groundwater reserves that are highly saline, reducing the sensitivity of this method for elements present in low concentrations. Figure 1 gives an approximate overview of groundwater salinity in Australia.

1.3 Exploration targets

Different minerals react with groundwater in different ways, resulting in different elements becoming present within groundwater samples. Table 1 provides an indication of what ore groups can be indicated by their associated elements in hydrogeochemical analysis, however groundwater conditions may not contain all these elements in a soluble and detectable phase.

> Table 1: Ore groups with associated elements to assist in mineral targeting (adapted from Butt et al. 2005 p2)

Ore group Associated elements

Magmatic Ni, Cu, Co, PGE, Te, As

Metasomatic Cr, PGE, Ni, Cu, Co, Au, Fe, Ti, V

Hydrothermal epigenetic Sn, W, As, Cu, Zn, W, Mo, Pb, Bi, Te,

Nb, Li, Be, Cs, Rb, U, Au, Re, Ag, Hg,

Se, Pt, Pd

Exhalative diagenetic Cu, Zn, Pb, As, Sb, Bi, Sn, Mo, Se, Ag,

Au, Ba, Hg, Te, Co, Cd, Mn, In, Ni

Marine sedimentary Fe, Mg, Al, Ca, Mn, P, Ti, Mn, Zn, Li, Ba

Residual & supergene Al, Fe, Ti, Nb, Ga, Mn, Zn, Zr, Ni, Co,

Cr, Au, Ag, As, W, Sb, Bi, Sr, Ca, K, U,

Ta, V, Se, Mo, Cu, Pb

Placers Au, Ag, W, Ti, Zr, Ba, Fe, Zr, Th, Cr, Sn,Nb, Ta


2. OVERVIEW: MINERAL EXPLORATION USING HYDROGEOCHEMICAL ANALYSIS

2.1 Background

The use of hydrogeochemistry for mineral exploration is increasing worldwide. Within Australia, extensive research was conducted by the Cooperative Research Centre for Landscape Environments and Mineral Exploration (CRC LEME) (Noble & Gray 2010; Gray 2001; de Caritat & Kirste 2005). Internationally, examples of this technique can be found in India (de Caritat et al. 2009), Canada (Maclean et al. 2000; Cameron, 1978), U.S.A. (Langmuir & Chantham 1980), Chile (Leybourne & Cameron 2006) and Russia (Goleva 1979).

This exploration method exploits the interaction between groundwater systems and geology. Research has shown that in known areas of mineralisation, chemical traces can be found within groundwater samples. By examining groundwater samples across an area of interest, concentrations in pathfinder minerals should indicate where mineralisation most likely occurs. From the inferences gathered by this exploration technique, traditional exploration methods should be used to confirm the location and economic viability of discovered deposits.

2.2 Limitations

In some parts of Australia, groundwater can be saline. This can present an issue as salts require the samples to be appropriately diluted before analysis, which lowers the concentration of elements that are being detected. Generally, in the case of cation analysis, dilution is needed if the total dissolved solids (salt content) exceeds 0.2 per cent. Dilution may result in trace (pathfinder) element concentrations dropping below analytical detection limits.

2.3 Benefits

By using groundwater analysis, mineral exploration can be completed faster and cheaper than by traditional techniques alone. Sample density is lower and if agricultural infrastructure (e.g. windmills, bores) is available, few, if any, bore holes will need to be drilled.


3. GROUNDWATER SOURCES

Sources of groundwater must be considered when planning a hydrogeochemical exploration program. Each type is subject to its own set of limitations, therefore comparisons during analysis must be made between similar sample sites. Table 2 shows the advantages and disadvantages of various groundwater sources while a summary is provided overleaf.

Groundwatersource

Advantages Disadvantages

Windmill Easy access;

no drilling costs

Potential for contamination if not

regularly flowing; restricted

available sample sites; only

shallow groundwater

Open well Easy access;

no drilling costs

Potential for contamination if not

regularly flowing; restricted

available sample sites; shallow

groundwater only

Water bore Easy access;

contamination

unlikely

Uncommon;

mainly shallow groundwater

RC or RAB

drill hole

Commonly

available in the

exploration area

of interest

Potential for contamination;

often not cased and may close or

collapse shortly after drilling

Diamond core

drill holes

Commonly

available in the

exploration area of

interest; well cased

and preserved

Commonly deep groundwater;

generally cased to a significant

depth preventing sampling from

shallow groundwater systems

Monitoring

bore

Easy access;

contamination

unlikely

Uncommon; shallow

groundwater only

> Table 2: Groundwater sources with advantages and disadvantages of each (modified from Noble & Gray 2010)


3.1 Windmills and wells

Established windmills and wells provide easy access to groundwater without the cost of drilling bores. However, in most regions (exceptions being areas such as Great Artesian Basin bores) these access points only allow testing of shallow groundwater systems and may be contaminated if they are not regularly flowing (Noble & Gray 2010).

3.2 Bores/drill holes

Where windmills and wells do not exist, it is necessary to utilise an existing bore hole or drill a new one. When choosing which bores to use, consideration must be made as to the depth of the system it is drawing water from. Samples should be compared with those drawn from a similar depth; otherwise it is possible that different groundwater systems could be sampled which may not share similar chemical properties.


4. MATERIALS

In order to successfully complete an exploration program, appropriate equipment is required. This section details what is needed to collect and store samples, as well as equipment to conduct analysis in the field and chemicals to prepare samples for laboratory analysis.

4.1 Water collection

Groundwater samples can be retrieved either by using the output from a windmill or bailing water from a bore hole. A summary of advantages and disadvantages is shown in Table 3.

If direct sampling from a windmill is used, all that is required to collect the sample is a plastic bucket.

When a bore is used, disposable plastic bailers are effective. If cleaned properly and still in good condition, they can be reused. Heavier steel bailers should be used when an angled drill hole is the access point to groundwater. If a depth marker is not on the bailer retrieval cord, depth marking should be made with a depth probe to ascertain the depth of the water table. Examples of bailers are shown in Figure 2.

4.2 Sample storage and filtration

New and clean HDPE plastic bottles are ideal for sample storage as they are chemically stable and unlikely to contaminate samples (Reimann et al. 1999). However, contamination risk should be monitored by way of testing control bottles (Reimann et al. 2007). CSIRO use two bottle sizes: 125 mL for

Collectionmethod

Advantages Disadvantages

Direct sampling

from windmill

Quick; only a bucket

is needed

Potential contamination,

restricted sites

Bailing from bore

hole

Quick; portable Potential contamination

> Table 3: Collection method with advantages and disadvantages (modified from Noble & Gray 2010)


anion, cation and alkalinity test samples and 1000 mL for Au/PGE test samples. Examples of suitable storage bottles are shown in Figure 3.

To avoid contamination by sediment and organic material, groundwater should be filtered immediately after retrieval before being stored or tested. Filtration units such as Nalgene® with a maximum filter paper pore size of 0.45 µm are ideal. These units require a pump to ensure filtration time is short. Alternatively, syringe filters can be used when small samples (< 50 mL) are required, though care should be taken to choose syringes with all-plastic parts rather than rubber to reduce the risk of contamination. Examples of filtration equipment is shown in Figure 4.

Samples should be stored in a cool place out of direct sunlight.

> Figure 2: Disposable and stainless steel/polycarbonate bailers on retrieval cords


> Figure 3: Storage bottles

> Figure 4: Filtration equipment


4.3 Field measurement equipment

Although the samples collected are to be tested at a later stage, pH, electrical conductivity (EC), redox potential (Eh) and temperature should be measured in the field. This is done to achieve the most accurate values possible, as pH, Eh and temperature are likely to change soon after the sample is collected and exposed to air. To do this, the following equipment is needed:

• Thermometer (often part of the pH or conductivity electrode)

• pH meter and electrode

• Conductivity meter and electrode

• Oxidation/Reduction Potential (ORP) meter and electrode

When choosing equipment it is important to consider the sensitivity required and units measured. For example, highly saline groundwater in parts of southern Australia means that EC meters should measure up to 200 mS/cm while other regions may only require an EC meter with a maximum measurement of 2000 µS/cm.

4.4 Field measurement chemicals

Chemicals are required to calibrate field measurement equipment and

prepare samples to take back to the laboratory.

Calibration solutions for the pH and EC meters are required and should be

used daily. The Eh meter should be calibrated fortnightly or after a field trip.

Depending on the type of electrodes used in each meter, a saturated solution

of KCl may be useful in storage. Deionised (DI) water is also required to rinse

electrodes. and other equipment

While most samples that will undergo later analysis can be prepared in the

laboratory, it is ideal, and straightforward, to prepare the Au/PGE sample on

site. For this, approximately 10 g of solid NaCl (1 Tbs) and carbon sachets are

required.


4.5 Carbon sachets

Activated carbon sachets are used to absorb and concentrate Au, Ag and PGE to allow low-level detection in the order of ng/L.

Carbon sachets are made by heat sealing a nylon mesh casing filled with 1 g of activated carbon. The casing dimensions should be approximately 2 cm x 4.5 cm. The carbon sachet is shown in Figure 5.

> Figure 5: Carbon sachet

1 cm


5. METHODS

5.1 Planning the study

While hydrogeochemical analysis has the potential to target some commodities with sample spacing up to 5 km, greater sample density is preferable. When planning an exploration study it is important to identify where samples will be obtained, what sources will be used and how much drilling is needed, if necessary. By plotting locations of known wells, bores and windmills, gaps in sample coverage will emerge. Consultation with various maps (e.g. cadastral, geological and hydrological maps) will help identify what sites would be suitable for bore drilling. From this a list of sample sites and sampling schedule can be created.

Ideally two people should carry out the field work, with one person collecting the samples while the other performs the “clean” work of filtering, sample preparation and measurements.

5.2 Site investigation

Before samples are collected, observations of the sample site should be taken. These should include:

• location (latitude and longitude or AMG coordinates etc)

• vegetation cover

• type of sample source (e.g. bore, windmill etc.)

• condition of source (e.g. Is it regularly used? Is it cased? If so, what condition is the casing in and what is it made of?)

• potential sources of contamination.

It is important to note these and any other observations so that samples can be compared with those obtained from similar sources (Quick Reference Guide 10.1).

5.3 Prepare equipment and filtration unit

Bailers or other water collection equipment should be rinsed with DI water prior to the collection of each sample, as should the filtration equipment. For


each sample, use a new filter paper or syringe filter and ensure it is free from contamination.

5.4 Prepare and label bottles

Label the following sized bottles with a site identification number and type of future analysis on the cap, shoulder and body of the bottle.

Bottles required are:

• bottle #1: anion analysis (125 mL)

• bottle #2: alkalinity analysis (125 mL)

• bottle #3: cation analysis (125 mL)

• bottle #4: Au/PGE analysis (1 L)

5.5 Sample groundwater

If collecting samples from a bore hole, lower the bailer until the sampler feels (or hears) the water table. Make a note of the depth. Continue to lower the bailer until the desired sampling depth is reached. To reduce the chance of oxidation, a sampling depth of at least 5 m is ideal (Gray & Noble 2006a; Giblin 2001) (Quick Reference Guide 10.2).

The first sample retrieved is used to rinse the bailer and the measurement electrodes. Discard and repeat the bailing procedure until approximately 2 L of water is collected.

5.6 Chemical analysis in the field

Place the initial bailer rinse-water into a container with the electrodes on and start the devices, but do not record the results. Empty the bailer. The second sample of water is used in the container to measure water parameters. Record Eh, pH, EC and temperature over 5-15 minutes until the readings stabilise. In some cases Eh may still vary up to 50 mV. Ideally, Eh measurements should be made in a flow-through cell to avoid the introduction of air into the sample that can cause erroneous measurements. For exploration purposes this is not often practical so it is important to measure the water quickly after it is retrieved and not to let the water stand for more than 15 minutes. Reduced groundwater (<200 mV) readings may


decrease and then begin to rise. If this occurs, record the lowest reading as this is the most relevant for later processing. For EC and pH, the most stable measurements are used. It is good practise, however, to record all measurements over time.

5.7 Filtered sample collection

Initially filter a sample of approximately 100 mL. After all the water has passed through the filter membrane, do a single rinse into bottle #1 (anion analysis) by pouring approximately 5 mL into the bottle, capping and shaking, then discarding the water. Pour the rest of the filtrate into the bottle.

Filter another 150 mL of water. Rinse twice, in the same manner as above. Discard. Fill bottle #3 with the remaining filtrate. This can be acidified in the field or laboratory with nitric acid to a concentration of 0.2% v/v or 250 µL of concentrated acid in 125 mL of sample.

5.8 Unfiltered sample collection

Fill bottle #2 (alkalinity analysis) with sample water so that it is completely full, taking care to ensure there are no air bubbles or space at the top. This is done to prevent reaction with the air.

Fill bottle #4 (Au/PGE analysis) to within 2 cm of the top of the bottle. Add the carbon sachet to the bottle, along with 10 g (1 Tbs) of NaCl. For simplicity and reduced contamination in the field the carbon and salt can be pre-added to the bottles.


6. ANALYSIS

6.1 Anion analysis

Bottle #1 is used for major anion, dissolved organic carbon (DOC) and PO4 analysis.

Ion Chromatography (IC) is used to detect major anions such as Br, Cl, F, NO3 and SO4. Commercial laboratories routinely conduct this analysis. Environmental analytical laboratories will be more familiar with these methods than mining-type laboratories.

DOC should be analysed using a dedicated DOC analyser while PO4

concentration can be established using titration.

6.2 Alkalinity analysis

Bottle #2 is used to establish concentration of HCO3. A set volume (e.g. 25 mL) of the sample should be titrated against a known concentration of acid (e.g. 0.01 M HCl) to an end point pH of 4.3. This can be conducted in the field using a burette, stirrer and pH meter, though it is rather time consuming. Commercial laboratories are capable of conducting this test. It is preferable to have the sample tested as soon as possible.

This method has a detection limit of approximately 2 mg/L.

Element/Compound

Method Detection limit Units

Br IC 0.1 mg/L

Cl IC 10 mg/L

DOC DOC analyser 0.2 mg/L

F IC 0.01 mg/L

NO3 IC 1 mg/L

PO4 Titration 0.009 mg/L

SO4 IC 3.5 mg/L

> Table 4: Typical detection limits for anions


6.3 Cation analysis

Bottle #3 is used for major, minor and trace metal analysis using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and ICP-Optical Emission Spectrometry (ICP-OES).

Element/Compound

Method Detection limit Units

Al ICP-OES

ICP-OES

ICP-OES

ICP-OES

ICP-OES

ICP-OES

ICP-OES

ICP-OES

ICP-OES

ICP-OES

ICP-OES

0.002 mg/L

As ICP-MS

ICP-MS

ICP-MS

ICP-MS

ICP-MS

ICP-MS

ICP-MS

ICP-MS

ICP-MS

ICP-MS

ICP-MS

ICP-MS

ICP-MS

ICP-MS

ICP-MS

ICP-MS

ICP-MS

0.01 µg/L

B 0.1 mg/L

Ba 0.01 µg/L

Ca 0.1 mg/L

Cd 0.01 µg/L

Ce 0.01 µg/L

Co 0.01 µg/L

Cr 0.01 µg/L

Cu 0.01 µg/L

Fe 0.004 mg/L

Ga 0.01 µg/L

K 0.08 mg/L

La 0.01 µg/L

Li 0.01 mg/L

Mg 0.04 mg/L

Mn 0.05 mg/L

Mo 0.01 µg/L

Na 0.006 mg/L

Nd 0.01 µg/L

Ni 0.01 µg/L

Pb 0.01 µg/L

Rb 0.01 µg/L

Sb 0.01 µg/L

Si 0.5 mg/L

Sn 0.01 µg/L

Sr 0.008 mg/L

U 0.01 µg/L

> Table 5: Typical detection limits for cations


To prevent Fe precipitates this sample is acidified using high purity nitric acid to a concentration of 0.2% v/v. If orange precipitates are still present a day after acidification, continue to add acid incrementally over the next few days until the precipitate is dissolved. Commercial laboratories can conduct this preparation step.

ICP-MS and ICP-OES can be conducted by most commercial laboratories.

6.4 Gold/Platinum group elements analysis

Bottle #4 is used to detect Au, Pt, Pd and Ag. The carbon sachet inserted into the 1000 mL bottle should be left for at least 4 days and the bottles should ideally be placed on a shaker or roller. The carbon sachet is removed and dried, and the volume of water collected is determined at this stage. Prior to measurement using ICP-MS the sachet is prepared by ashing the nylon mesh and C, followed by dissolution in aqua regia.

This process can be conducted by specialised commercial laboratories.

6.5 Mapping and interpreting results

To identify areas of higher concentration of the target mineral, it is useful to overlay concentrations of relevant elements from each sample site on a map. An example of this is shown in Figure 6.

Element mapping alone won’t always suggest areas of mineralisation. It is often necessary to look at an aggregate of elements or whether the groundwater is near saturation point for a particular mineral. This is known as the saturation index (SI).

Element/Compound

Method Detectionlimit

Units

Ag ICP-MS Carbon

ICP-MS Carbon

ICP-MS Carbon

ICP-MS Carbon

ICP-MS Carbon

20 ng/L

ng/L

ng/L

ng/L

ng/L

Au 2

Bi 5

Pd 3

Pt 2

> Table 6: Detection limits for Au/PGE in activated carbon


6.6 Saturation Index

Saturation indices for each water sample for different minerals can be calculated using various computer programs, such as PHREEQE (Parkhurst et al. 1980), many of which are available online. If the SI for a mineral equals zero, the water is in equilibrium with that mineral. If SI is less than zero, groundwater is under-saturated, suggesting that if minerals are present they are likely to dissolve. If SI is greater than zero, the groundwater is over-saturated with respect to that mineral, suggesting that mineral precipitation may occur.

Figure 6: Example of mapping concentrations from sample sites. This image shows Ag concentrations in the northeast Yilgarn Craton (Gray et al. 2009).

!C

!C

!C

!C

!C

!C

!C!C

!C

!C

!C

!C

!C

!C!C

!C

!C

!C

122°E121°E120°E119°E118°E

26°S

27°S

28°S

29°S

Ag (ng/L)

2700 - 8200

700 - 2290

450 - 680

250 - 428

150 - 223

100 - 120

50 - 73

< 50

!C Au Mines

100 km


7. CASE STUDY 1: HARMONY GOLD DEPOSIT

Source: Noble et al. 2010

7.1 Introduction

This case study examined which elements are useful pathfinders to locate gold, utilising known deposits on the northern Yilgarn Craton in Western Australia.

7.2 Location

The Harmony Au deposit is located within a depositional plain approximately 90 km north of Meekatharra in the mid west region of Western Australia. The region is arid, with low, irregular rainfall averaging 240 mm per annum (Bureau of Meteorology, 2008). The sparse vegetation consists largely of mulga (Acacia aneura), and drought-resistant shrubs and grasses. The deposit was discovered in 1991 by RAB drilling to saprolite and fresh rock.

7.3 Regolith characteristics

The site is located in the Palaeoproterozoic Bryah Basin. The mineralisation is on the contact between the Ravelstone and Narracoota Formation. The Ravelstone Formation is a thick turbidite sequence of fine-grained, mafic, feldspathic and lithic wackes. The Narracoota Formation consists of folded mafic and ultramafic volcanics. The sequences are metamorphosed to lower to middle greenschist facies (Pirajno & Occhipinti 1995; Pirajno et al. 1995). Primary mineralisation is associated with hematitic quartz veins and carbonate-filled breccia, with Au and Ag occurring as inclusions in pyrite with associated pyrrhotite, pentlandite, chalcopyrite and scheelite. Trace element signatures in the mineralised rocks include As, Te, Zn and Pb, with Au and W the most useful pathfinders (Harper et al. 1998).

The deposit has been weathered to ferruginous saprolite and covered by colluvium-alluvium. Colluvium-alluvium in the area is 7-12 m thick, but directly over the deposit (a palaeo-high) it is 1-3 m thick. The upper few metres of the colluvium-alluvium are silicified to a red-brown hardpan. Below this, the material is similar, but finer grained and uncemented. Adjacent to the deposit, but beneath the colluvium-alluvium, the deposit is flanked by a lateritic duricrust of approximately 8 m thickness. A palaeochannel drains from 1 km


south of the deposit in a northwest direction (Figure 7). The palaeochannel is filled with 10-24 m of mottled, thick, puggy, clay-rich sediments (Robertson 2001).

7.4 Groundwater depth and chemistry

The shallow aquifer < 2 km from the deposit has a neutral pH, is fresh and generally similar to those from the northern Yilgarn Craton. The groundwater flows southeast, towards the channel.

7.5 Sample results

Approximately 40 samples were collected from drill holes over a 6 km2 area. Dissolved Au concentrations are low (2-11 ng/L) and ~100 times less than in mineralised areas around Kalgoorlie. Despite these low concentrations,

250 m

25°39'10" S

118°37'50" E 118°37'50" E

25°39'10" S

250 m

Groundwater flow directionPalaeochannel

Mo in water ( g/L)µ

< 0.20.3 - 2

2 - 4

4 - 9

Au in water (µg/L)

0.002 - 0.003

0.003 - 0.004

0.005 - 0.006

0.007 - 0.011

1600 - 3200 400 - 1600 100 - 400 < 100Au in Regolith ( g/kg)µ > 3200

> Figure 7: Dissolved Au and Mo concentrations in groundwater superimposed over maximum Au concentrations in regolith. Mining pit outlined towards the centre; paleochannel and groundwater flow direction also shown.


dissolved Au is a good target element for mineralisation in the region, as local background is lower still.

Some groundwater has concentrations of Au below detection over mineralisation that may indicate inconsistencies in Au mobility in this environment. Additionally, Sc, Mo, W and possibly Rb have elevated groundwater concentrations in areas of Au mineralisation and are more consistent pathfinders than Au itself in groundwater at this local scale. This elemental suite is similar, though more limited, to those observed elsewhere in the northern Yilgarn for detecting Au mineralisation. Dissolved As correlated with the areas of major hydrothermal alteration.

7.6 Conclusion

Through sampling groundwater from 40 bore holes near the Harmony Au deposit, Au, Mo, W and Rb concentrations in groundwater corresponded to known concentrations of Au in the regolith.


8. CASE STUDY 2: GROUNDWATER URANIUM FROM FARM WELLS AND BORES

Source: Noble et al. 2011

8.1 Introduction

Hydrogeochemistry has been demonstrated to be a useful tool in mineral exploration, though its efficacy over a multi-catchment area is much less known. This case study examines the application of this exploration method at a regional scale, while also examining the role of the saturation index (SI) in targeting known U deposits.

8.2 Location

The northern Yilgarn region is semi-arid to arid with hot, dry summers and cool winters, with low, irregular rainfall between 200-300 mm per annum (Bureau of Meteorology, 2010). The sparse vegetation consists largely of mulga (Acacia aneura), and drought-resistant shrubs and grasses. Halophytic shrubs

Drainage divide

123°E122°E121°E120°E119°E118°E

26°S

27°S

28°S

29°S100 km

Meekatharra

Cue

Sandstone

Wiluna

Leinster

Laverton

Mt Magnet

Leonora

Towns

Study area

Drainage divide

Catchmentboundaries

RegionalGroundwaterSamples

Playas

> Figure 8: Northern Yilgarn Craton study area showing towns, water catchments, playas and sample locations


are located on the fringe of the playas. The study area, including towns, water catchments, playas and sample locations is shown in Figure 8. The northern Yilgarn is separated from the south by the Menzies Line, a distinct ecological divide between 29º to 30º S latitude (Anand and Butt, 2010) where soil type, groundwater and vegetation change over a relatively short distance (~50 km; Butt et al., 1977). Generalised and distinctive differences in conditions between the north and south Yilgarn are well known and are influential in U deposit formation, but the evolution of these conditions has only recently been investigated (Gray and Noble, 2006b; Peiffer et al., 2009).


The northern Yilgarn Craton consists of Archaean granite and granitic gneiss with extensive north-north west oriented, elongate greenstone belts (Myers, 1997; Williams, 1975). The granitic rocks comprise deformed and metamorphosed granodiorite-monzogranite. The greenstones generally comprise mafic and ultramafic volcanic rocks underlain by quartzite, banded iron formation and minor felsic volcanics. A summary of the tectonic evolution of the Yilgarn Craton is given by Cassidy et al. (2006).

The topography is broadly flat with Cainozoic alluvial transported cover of varied thickness (a few metres to tens of metres). Elevation across the sampling area ranges from 360 to 600 m above sea level, gradually decreasing north to south and is split by a north-south trending drainage divide (Figure 8). The relatively flat surface hides complex underlying regolith that has been exposed to significant events of weathering, erosion, deposition and a variety of climatic conditions. A comprehensive review of the regolith and geomorphology of the region is given by Anand and Paine (2002). Major complexity in composition and ages of the weathered surface occurs in the northern Yilgarn. The dominant residual regolith on uplands is characterised by saprock, grading upwards to saprolite that is commonly bleached. Overlying this are clay- and quartz-rich, mottled- and ferruginous zones (lateritic residuum) near the surface. The channels are weathered surfaces that have been filled with clays, sand and silt with lenses of carbonates, lignites and ferruginous gravel (Anand and Paine, 2002). Carbonates are formed primarily in the upper part of the channel. Generalised cross sections of these two


dominant landform features are shown in Figure 9. Other common landforms of the northern Yilgarn Craton are sand plains, plateaus, breakaways, colluvial and alluvial plains, minor bedrock exposure, playas and sand dunes. Soils are dominantly acidic, sandy with red-brown hardpans and lack significant calcrete horizons except in channels.


Regionally, the groundwater is relatively fresh and of neutral pH (Gray, 2001). Salinity tends to increase towards the drainages and valley floors where, in many cases, there are playas (with a salt crust). The water table is commonly 5 to 40 m below the surface, with the shallowest depth to groundwater occurring in the valley floors.

Oxidized groundwater (Eh >260 mV) is common in the northern Yilgarn shallow aquifers, however reduced groundwater (Eh <260 mV) has been observed and related to nearby sources, such as reduced palaeodrainage sediments, rock sulphides, or even reduced water sources from deeper fault systems (Gray 2001; Gray and Noble, 2006a).

The northern Yilgarn region is poorly studied and understood hydro-geologically and information is limited to the palaeodrainage sequences to the southwest of our study area and some bedrock aquifers near mine water supplies (Johnson et al., 1999). The palaeodrainage near-surface aquifer has a low permeability with hydraulic conductivity of <2.5 m day-1 in the dominant alluvial clay layers. This conductivity is influenced by the presence of highly permeable sand and gravel lenses (particularly at the base of the drainage) that increase conductivity, as well as siliceous or ferruginous cementation reducing permeability. Calcretes in the upper units of the palaeodrainage aquifer that host the U mineralisation have variable permeability. Hydraulic gradients are 0.2-2 m km-1 and a preliminary estimate of groundwater residence time in these channel systems is 100,000 years (Johnson et al., 1999). Discharge is principally by evaporation from the playas (Commander et al., 1992), with recharge from the palaeochannel tributaries and surface creating a continuous groundwater flow. Residence time may be even greater in some of the regional playas such as Lake Austin that may act as a sump with no obvious exit palaeodrainage. The palaeodrainage system in the eastern section of the


study is linked with groundwater ultimately flowing from Lake Carey and Lake Raeside palaeodrainage to the Eucla Basin, 350 km SE (Johnson et al., 1999). Away from the drainage axes, the surface aquifer flow rates are varied and not well studied, but likely to be slower as the porous channel sands and gravels that are present in the major drainage systems (Figure 9b) are absent (Figure 9a). The calcrete palaeochannels are major aquifers and used as the source for watering stock, human consumption (including town water supplies) and irrigation.

8.5 Sample results

As U mineralisation occurs as carnotite, several pathfinders were considered. These include U, various compounds required for U to remain mobile in groundwater or associated with mineralisation, as well as the carnotite saturation index.

Uranium concentrations in the northern Yilgarn range from 1 to 700 µg/L with a mean concentration of 14 µg/L. Dissolved U alone is a useful targeting element, producing coherent anomalies near known deposits using the ~5 km sample spacing. In particular, the greatest U concentrations are close to the Yeelirrie deposit (6.5 and 13.7 km down drainage from Yeelirrie), identifying the area as the strongest target, consistent with Yeelirrie being the largest known deposit. Other known deposits also have elevated U concentrations compared to the background. The background data was calculated on all samples greater than 20 km from a known deposit. Results show significant differences for U in the groundwater near the deposit compared with background. The mean U concentration for groundwater within a 20 km radius of a deposit is 23 µg/L, compared to 9 µg/L for background ground water concentrations. The 95th percentile for near deposit and background groundwater U is 92 compared to 35 µg/L, respectively. The majority of the higher U concentrations are in the topographically lower parts of the landscape (drainage channels) and are evident with the catchment details on the map and the Multi Resolution Valley(MrVBF), a proxy for regolith depth and palaeodrainage (Figure 10).


Mottled zone

Clay zone

Saprolite

Saprock

Bedrock

Lateritic duricrust

Soil

Lateritic gravel

Lag

100 m

Calcrete

Quaternary / Tertiarysands + clays

Tertiary palaeochannelclay

Tertiary palaeochannelsand/gravel

Saprolite

Bedrock

Water table

B

A

> Figure 9: A) Standard soil profile for the study region

> Figure 9: B) Soil profile and water table level in a paleochannel


U concentrations alone are not enough to target all areas of mineralisation: for example, the second largest known deposit, Lake Maitland, was not identified by U concentrations. Rather, a measurement of the carnotite saturation index (SI) was a better indication of known mineral deposits (Figure 10). Other elements associated with U mineralisation and transportation (e.g. V, K, P, HCO3, PO4) did not directly indicate where known deposits were located.

8.6 Conclusion

Uranium deposits can be targeted using groundwater analysis on a regional, multi-catchment scale. Uranium concentrations and the carnotite SI are ideal methods for detecting secondary U deposits.

> Figure 10: Carnotite saturation index for groundwater from the northern Yilgarn. Background is the MrVBF index shaded with the lightest areas indicative of thick cover and wide, flat valley bottoms (palaeodrainage). Catchment boundaries, major economic U deposits, known U deposits and U prospects are shown

Drainage divide

123°E122°E121°E120°E119°E118°E

26°S

27°S

28°S

29°S100 km

Carnotite SI KUO VO2 4

SaturatedPossibly saturatedClose to saturated

Lake MaitlandYeelirrie

Watercatchments

Economic uraniumdeposits

Sub-economic uraniumdeposits and prospect

MrVBF cover proxy index

Thick cover

Thin coverJust undersaturatedUndersaturated

Meekatharra

Cue

Sandstone

Wiluna

Leinster

Laverton

Mt Magnet

Leonora


9. CASE STUDY 3: GROUNDWATER FOR NICKEL SULFIDE EXPLORATION

Source: Gray and Noble, 2006a; Gray et al., 2009

9.1 Introduction

As target elements for nickel sulfide and volcanogenic massive sulfide (VMS) ore deposits are readily absorbed by clays and Fe oxides, their relative concentrations in groundwater cannot be relied on for mineral exploration. This study examines the use of PGE and multi-element indices as pathfinders in locating known nickel sulfide deposits.

9.2 Location

The Norseman-Wiluna greenstone belt extends through the NE Yilgarn Craton (Figure 11) and hosts numerous major Ni deposits. The area is semi-arid to arid and has a Mediterranean climate with hot, dry summers and cool, wet winters. Mean annual rainfall is between 200-300 mm, similar to the Harmony study site (Bureau of Meteorology 2010). Mulga dominates the vegetation with minor drought resistant shrubs and grasses. The primary land use is cattle grazing and mining.


Greenstones, including ultramafic and mafic volcanics, are enclosed within granitoids. This greenstone belt is abundantly mineralised, hosting numerous Ni sulfide deposits, including Cosmos, Honeymoon Well (Wedgetail, Corella, Harrier, Hanibals), Harmony, Mt Keith, Perseverance, Prospero, Rocky’s Reward, Sinclair, Waterloo, Weebo and Yakabindie (Six Mile Well/Goliath). Most mineralisation is in stratiform volcanic-hosted deposits, related to komatiite flows (Morris & Sanders 2001). The mineralisation is varied massive, disseminated, matrix and remobilized stringer and breccia hosted sulphide mineralisation of pentlandite and pyrrhotite. The sulfides also contain significant concentrations of PGE. A comprehensive review of the geology and Ni mineralisation styles and settings is given by Barnes (2006).

The topography is broadly flat with ancient alluvial transported cover of varied thickness (a few metres to tens of metres). Soils are dominantly acidic,


sandy with red-brown hardpans and lack significant calcrete horizons except in channels. A comprehensive review of the regolith and geomorphology of the region is given by Anand & Paine (2002).


The watertable along the greenstone belt is 10 to 40 m below the surface. The groundwater study included approximately 300 samples from in and around eight deposits along 160 km of the Norseman-Wiluna greenstone belt between Leonora and Wiluna. Gray & Noble (2006a) investigated the evolution of groundwater and the hydrogeochemical signature related to sulfide weathering.

9.5 Sample results

The concentration of Pt and Pd in the groundwater was determined as part of this study using pre-concentration onto activated carbon sachets (Noble & Gray 2010; Giblin 2001; Gray 2001). This method showed Pt and Pd (and W) are a useful vector to Ni mineralisation. The concentrations of PGE in the NE Yilgarn groundwater is very low (commonly <1 ng/L), making the use of these elements as pathfinders difficult. Samples of >1 ng/L (detection) are considered anomalous. Results show that higher concentrations of Pt, as well as any detectable Pd, are found mostly within 2 km of mineralisation (Figure 11). At Honeymoon Well, the four mineralised zones are all delineated with detectable Pt (>1 ng/L, Figure 11).

The deposits all have elevated, but sporadic, Pt concentrations in the groundwater around the deposits. The lack of a PGE groundwater signature does not indicate an absence of Ni sulfide mineralisation (i.e. could be a false negative), but a positive PGE result is a strong indicator of mineralisation. The groundwater around the Jaguar VMS Zn deposit (Figure 11) is also enriched in PGE, indicating that PGE in groundwater may be indicators of several different types of sulfide mineralisation. The Ni sulfide mineralization in the Norseman-Wiluna greenstone belt contains significant PGE concentrations, but the weathering rates and mobility of PGE means concentrations are expected to be limited. Regardless, the use of PGE is more effective than the direct measurement of the target element (Ni for NiS deposits and Zn and Cu for


#

250000 mE 300000 mE

6950000 mN

7000000 mN

6900000 mN

Honeymoon Well(4 deposits)

Yakabindie

Harmony

Waterloo

Jaguar

Pt (ng/L)

10 - 91

4 - 8

2 - 4

1 - 2

0 - 1

6850000 mN

Geology

230000 mE 240000 mE 250000 mE

7000000 mN

7010000 mN

7020000 mN

7030000 mN

Mineralization

Ultramafic rocks

Mafic rocks

Mafic intrusive volcanics

Felsic rocks

Granite rocks

0 20 km

RNf012-11

0 5 km

> Figure 11 Platinum concentration in groundwater of the Norseman-Wiluna greenstone belt in the NE Yilgarn, with a more detailed depiction of the Honeymoon Well area. Grid coordinates are UTM Zone 51, GDA 94.


DGf001-11

Geology

Ultramafic rocks

Mafic rocks

Mafic intrusive volcanics

Felsic rocks

Granite rocks

265000 mE

6925000 mN

6930000 mN

6935000 mN

270000 mE

250000 mE 300000 mE6850000 mN

6900000 mN

6950000 mN

7000000 mN

0 20 km

0 2 km

NiS Index> 0.85

0.75 - 0.85

0.60 - 0.75

0.40 - 0.60

< 0.40

> Figure 12: NiS Index (Ni+Co+Pt+W) in groundwater of the Norseman-Wiluna greenstone belt in the NE Yilgarn, with a more detailed depiction of the Harmony NiS deposit and adjacent exploration to the north

the VMS deposits) alone. Even more consistent anomalies can be observed by combining elemental data. Thus, the NiS index (combining rescaled data of Ni, Co, Pt and W results) very strongly delineates the Ni sulfide ore-bodies along the belt (Figure 12).


Chromium in groundwater may be used to indicate underlying ultramafic lithologies in this region (Gray & Noble 2006). Chalcophile elements (i.e. As, Mo, Ag, Sb, W, Ti and Bi) are commonly enriched and more mobile in neutral groundwater in direct contact with weathering sulfides, suggesting regional groundwater sampling may be effective at locating these types of deposits.

9.6 Conclusion

PGE, in conjunction with target elements, have been shown to be useful pathfinders in nickel sulfide and VMS deposit exploration.


10. QUICK REFERENCE GUIDES

10.1 Standard Abbreviations For Sampling

10.2 Materials• Bailer on retrieval cord

• Bucket

• 25 mL HDPE bottles (3 per site)

• 1 L HDPE bottles (1 per site)

• Permanent marker

• DI water

• Thermometer

• pH meter and electrodes

• pH calibration solutions

• EC meter and electrodes

• EC calibration solutions

• Eh meter and electrodes

• Eh calibration solutions

• Extra KCl electrode storage solution (if used)

• Carbon sachets (1 per site)

• NaCl (10 g per site)

• Filtration unit

• Spare filters

• GPS unit

• Stationary for recording observations and results

1, 2, 3, 4 - use always. 5, 6 as required

SB: Still Bore

SW: Still Well

FB: Flowing Bore

FW: Flowing Well

MP: Metal stem

PP: Poly stem

CP: Clear (assumed if not coded)

O: Open

C: Closed

V: vertical (assumed if not coded)

A: angled ... Or

deg: estimated angle

U: Outflow return to well from tank(outflow under inflow)

A: Outflow return to well from tank(outflow above inflow)

S: Sampled from outflow

B: Bailed from flowing windmill(access, no wind etc)

1

2

3

4

5

6


10.3 General sampling and testing methods flowchart

Acidify

Take notes of site

Determine depth

Bail initial sample Rinse electrodesDiscard

Calibrate electrodes

Discard

Bail ~ 2 L of water

Set up filter

Measure pH Eh EC

Filter ~ 50 mL

Fill alkalinity bottle #2

To laboratory –titrate for HCO3

Pour to anions bottle #1

Discard extra filtrate

Filter ~150 mL

Use 5 mL to rinsecations bottle

To laboratory for ICanions analysis

Pour to cations bottle #3

To laboratoryfor ICPMS/OEScations analysis

Fill 1000 mL bottle #4

Add C and NaCl

Shake 7 days

Remove and dry C

Measure volume

To laboratory forweighing, ashing,

aqua regiadigestionand analysis by

ICPMS/OES


11. ACKNOWLEDGEMENTS

This Hydrogeochemistry Field Guide presents research conducted by CSIRO scientists, Dr David Gray and Dr Ryan Noble, as well as many of their CSIRO colleagues at the Australian Resources Research Centre (ARRC) in Perth, Western Australia. The field guide is a culmination of research conducted through CSIRO’s Minerals Down Under Flagship, CRC LEME and DET CRC.Many thanks go to them for their support, proofing and guidance in assembling this Guide. Special thanks to Alan Gill, a science communication student from The University of Western Australia’s Science Communication program, for compiling and pulling together all the vital material required to produce this publication.


12. REFERENCES

Anand, R.R. & Paine, M. 2002. Regolith geology of the Yilgarn Craton, Western Australia: implications for exploration. Australian Journal of Earth Sciences, 49, 3-262

Anand, R.R. & Butt, C.R.M. 2010. A guide to mineral exploration through the regolith in the Yilgarn Craton, Western Australia. Australian Journal of Earth Sciences, 57, 1015-1114

Barnes, S.J. (Ed) 2006. Nickel deposits of the Yilgarn Craton L geology, geochemistry and geophysics applied to exploration. Special Publication Number 13, Society of Economic Geologists, Littleton, Co.

Bureau of Meteorology, 2008. Climate data from regional (Peak Hill) weather stations and Australian rainfall map online. http://www.bom.gov.au/ accessed September 10, 2008. Bureau of Meteorology, Canberra, ACT

Bureau of Meteorology, 2010. Climate data from regional (Leinster Aero) weather stations and Australian rainfall map online. http://www.bom.gov.au/ accessed July 7, 2010. Bureau of Meteorology, Canberra, ACT

Butt, C.R.M., Horwitz, R.C., & Mann, A.W. 1977. Uranium occurrences in calcrete and associated sediments in Western Australia. CSIRO Research Laboratories Division of Mineralogy Report. FP 16. 67p

Butt CRM, Cornelius M, Scott KM, Robertson IDM, 2005, Regolith expression of Australian ore systems, Cooperative Research Centre for Landscape Environments and Mineral Exploration, Perth, WA, 423 pages.

Cameron, E.M., 1978. Hydrogeochemical methods for base metal exploration in the northern Canadian Shield. Journal of Geochemical Exploration, 10, 219-243

Cassidy, K.F., Champion, D.C., Krapez, B., Barley, M.E., Brown, S.J.A., Blewett, R.S., Groenwald, P.B. & Tyler, I.M. 2006. A revised geological framework of the Yilgarn Craton, Western Australia. Western Australia Geological Survey Record 2006/8

Commander, D.P., Kern, A.M.M. & Smith, R.A. 1992. Hydrology of the Tertiary palaeochannels in the Kalgoorlie Region (Roe Palaeodrainage): Western Australia Geological Survey, Record 1991/10, 56p


de Caritat, P. & Kirste, D. 2005. Hydrogeochemistry applied to mineral exploration under cover in the Curnamona Province. MESA Journal, 37, 13-17

de Caritat, P., McPhail, D.C., Kyser, K. & Oates, C.J. 2009. Using groundwater chemical and isotopic composition in the search for base metal deposits: hydrogeochemical investigations in the Hinta and Kayar Pb-Zn districts, Idia. Geochemistry: Exploration, Environment, Analysis, 9, 215-226

Giblin, A. 2001. Groundwaters: Geochemical pathfinders to concealed ore deposits. CSIRO Exploration and Mining, North Ryde.

Goleva, G. A. 1979. Methodologic bases for hydrogeochemical exploration of ore deposits and problems of their future improvement, International Geology Review, 21, 9, 1079-1092p

Gray, D.J. 2001. Hydrogeochemistry in the Yilgarn Craton. Geochemistry: Exploration, Environment, Analysis, 1, 253-264

Gray, D., Noble, R. & Reid, N. 2009. Hydrogeochemical mapping of the northeast Yilgarn, Minerals and Energy Research Institute of Western Australia Report no. 280

Gray, D.J. & Noble, R.R.P. 2006a Nickel hydrogeochemistry of the northeastern Yilgarn Craton, Western Australia. CRC LEME Open File Report 243R / CSIRO Exploration and Mining Report P2006/524, 133p

Gray, D.J. & Noble, R.R.P. 2006b. Recent advances in hydrogeochemistry. In: Fitzpatrick, R. (Ed). Regolith Symposium. CRC LEME, Perth. pp. 109-112

Harper, M.A., Hills, M.G., Renton, J.I. & Thornett, S.E. 1998. Gold deposits of the Peak Hill area. In: Berkman, D.A. & Mackenzie (Eds.), Geology of the Australian and Papua New Guinean Mineral Deposits. The Australasian Institute of Mining and Metallurgy, Melbourne, 81-88

Jacobson, G. & Lau., J.E. (compilers) 1987. Hydrogeology of Australia (1:5 000 000 scale map). Bureau of Mineral Resources, Canberra.

Johnson, S.L., Commander, D.P. & O’Boy, C.A. 1999. Groundwater resources of the Northern Goldfields, Western Australia. Water and Rivers Commission, Hydrogeological Record Series , Report HG 2, 57p


Langmuir, D. & Chatham, J.R., 1980. Groundwater prospecting for sandstone-type uranium deposits: a preliminary comparison of the merits of mineral-solution equilibria, and single –element tracer methods. Journal of Geochemical Exploration, 13, 201-219.

Leybourne, M.I. & Cameron, E.M., 2006. Composition of groundwaters associated with porphyry-Cu deposits, Atacama Desert, Chile: Elemental and isotopic contraints on water sources and water-rock interactions. Geochemica et Cosmochemica Acta, 70, 1616-1635

Maclean, B. J., Al, T. A. & Blowes, D. W. 2000. The use of hydrogeochemistry for mineral exploration in areas of thick glacial overburden; Tillex copper zinc deposit, Matheson, Ontario. Abstracts with programs – Geological Society of America, 32, 7, p8

Morris, P.A. & Sanders, A.J. 2001. The effect of sample medium on the regolith chemistry over greenstone belts in the northern Eastern Goldfields of Western Australia. Geochemistry: Exploration, Environment, Analysis, 1, 201-210

Myers, J.S. 1997. Preface: Archaean geology of the Eastern Goldfields of Western Australia – regional overview. Precambrian Research, 83, 1-10

Noble, R.P. & Gray, D.J.2010. Hydrogeochemistry for mineral exploration in Western Australia (I): Methods and equipment, Explore Newsletter, 146, 2-11

Noble, R.P., Gray, D.J., Robertson, I.D.M. & Reid, N. 2010. Hydrogeochemistry for mineral exploration in Western Australia (II): Case Studies, Explore Newsletter, 146, 12-17

Noble, R., Gray, D. & Reid, N. 2011. Regional exploration for channel and playa uranium deposits in Western Australia using groundwater. Applied Geochemistry (in press)

Parkhurst, D. L., Thorstenson, D. C. & Plummer, L. N. 1980. PHREEQE, a computer program for geochemical calculations. U.S. Geological Survey Water Resources Investigations Report WRI 80-96

Peiffer, S., Oldham, C., Salmon, U., Lillicrap, A. & Kusel, K. 2009. Does iron cycling trigger generation of acidity in groundwaters of Western Australia? Environmental Science and Technology, 43, 6548-6552


Piranjo, F. & Occhipinti, S. 1995. Byrah, W.A. (Preliminary edition). Western Australian Geological Survey, Perth. 1: 100 000 Geological Series

Pirajno, F., Adamides, N.G., Occhipinti, S., Swager, C.P. & Bagas, L. 1995. Geology and tectonic evolution of the early Proterozoic Glengarry Basin, Western Australia. Western Australian Geological Survey Annual Review 1994-1995

Reiman, C., Siewers, U., Skarphagen, H. & Banks, D. 1999. Does bottle type and acid-washing influence trace element analyses by ICP-MS on water samples? At test Covering 62 elements and four bottle types: high density polyethene (HDPE), polypropene (PP), fluorinated ethene propene copolymer (FEP) and perfluoroalkoxy polymer (PFA). The Science of the Total Environment, 239, 111-130

Reiman, C., Grimstvedt, A., Frengstad, B. & Finne, E. 2007. White HDPE bottles as source of serious contamination of water samples with Ba and Zn. Science of the Total Environment, 374, 292-296

Robertson, I.D.M. 2001. Geochemical exploration around the Harmony gold deposit, Peak Hill, Western Australia. Geochemistry: Exploration, Environment, Analysis, 4, 113-127

Williams, I.R. 1975. Eastern Goldfields province. In: Geology of Western Australia. Western Australia Geological Survey Mem 2, 33-55


13. GLOSSARY

13.1 Abbreviations

CRC LEME Cooperative Research Centre for Landscape Environments and Mineral Exploration

DET CRC Deep Exploration Technologies Cooperative Research Centre

DI deionised

DOC dissolved organic carbon

EC electrical conductivity

Eh oxidation/reduction potential

HDPE high density polyethylene

IC ion chromatography

ICP-MS inductively coupled plasma mass spectrometry

ICP-OES inductively coupled plasma optical emission spectrometry

MrVBF multi-resolution index of valley bottom flatness

PGE platinum group elements

RAB rotary air blast

RC reverse circulation

SI saturation index

VMS volcanogenic massive sulfide


13.3 Units

Distance/Size

km kilometresm metrescm centimetresmm millimetresµm micrometres

Volume

L litresmL millilitres

Mass

g gramsmg milligramsµg microgramsng nanograms

Measurements

mS milliSiemensµS microSiemensmV millivolts

Concentration

v/v volume per volume M molar concentration (1M = 1 mol L-1)

mg/L milligrams per litreµg/L micrograms per litreng/L nanograms per litre

Ag silverAs arsenicAl aluminiumAu goldB boronBa bariumBe berylliumBi bismuthBr bromineC carbonCa calciumCd cadmiumCe ceriumCl chlorineCs caesiumCo cobaltCr chromiumCu copperF fluorineFe ironGa gallium

HCl hydrochloric acidHCO3 bicarbonateHg mercuryIn indiumK potassiumKCl potassium chlorideLa lanthanumLi lithiumMg magnesiumMn manganeseMo molybdenumNa sodiumNaCl sodium chlorideNb niobiumNd neodymiumNi nickelNO3 nitrateP phosphorousPb leadPd palladiumPO4 phosphate

Pt platinumRb rubidiumRe rheniumSb antimonySc scandiumSe seleniumSi siliconSn tinSO4 sulphateSr strontiumTa tantalumTe telluriumTh thoriumTi titaniumU uraniumV vanadiumW tungstenZn zincZr zircon

13.2 Elements/Compounds

MINERALS DOWN UNDER (MDU) FLAGSHIP EXPLORATION AND TECHNOLOGY GUIDES

This series is designed to help mineral explorers understand and work more efficiently and successfully in the Australian environment where access and consistent sample media can be difficult to obtain and regolith cover commonly masks ore deposits.

This guide is the first in a series of MDU Exploration and Technology Guides which complement the previously published CRC LEME Explorers’ Guide series.

The field guide demonstrates applied hydrogeochemistry and highlights the robust, relatively inexpensive and straight forward methods of groundwater sampling to explore for mineral deposits across Australia.

Using the guide – The field guide has a number of sections covering:

• The purpose, background, limitations and benefits of hydrogeochemistry (Sections 1 and 2)

• The sources of groundwater, specific materials, methods and analytical steps (Sections 3 to 6)

• Case studies with applied examples of hydrogeochemical exploration for Au, U and Ni deposits (Sections 7 to 9)

There are quick reference guides with a glossary at the back.

MDU Discovery Theme objective: to drive exploration success and reduce the significant risks and costs associated with mineral exploration, the Flagship provides an integrated research and development program that focuses on the unique challenges of the Australian landscape and its geological endowment and architecture.

Series Editor : Ryan Noble

FIELD GUIDE FOR MINERAL EXPLORATION USING HYDROGEOCHEMICAL ...

Documents

Transcript of FIELD GUIDE FOR MINERAL EXPLORATION USING HYDROGEOCHEMICAL ...