Gold-in-calcrete: A continental to profile scale study of regolith carbonates and their association with gold mineralisation

Robert Charles Dart, B.AppSc (Hons)

Geology and Geophysics School of Earth and Environmental Sciences The University of

Thesis submitted as fulfilment of the requirements for the degree of Doctor of Philosophy in the Faculty of Science,

March 2009 Contents

LIST OF FIGURES...... IV LIST OF TABLES...... VIII ABSTRACT...... IX ORIGINALITY STATEMENT...... X ACKNOWLEDGEMENTS ...... XI DEFINITION OF ABBREVIATIONS AND ACRONYMS ...... XIII PUBLICATIONS AND CONFERENCE ABSTRACTS DERIVED FROM THIS THESIS RESEARCH ...... XIV INTRODUCTION ...... 1 1.1. PROJECT OVERVIEW...... 1 1.2. REGOLITH TERMINOLOGY USED IN THIS THESIS ...... 2 1.3. RESEARCH OUTLINE AND THESIS STRUCTURE...... 4 1.3.1. Module 1: Source of calcium in regolith carbonates...... 5 1.3.2. Module 2: Calcrete-gold in the landscape: Regolith-landform controls at Tunkillia, South ...... 5 1.3.3. Module 3: Gold in the regolith profile: Pedogenic controls at White Dam, ...... 6 1.4. SUMMARY OF PROJECT AIMS ...... 6 REGOLITH CARBONATES AND THEIR USE IN MINERAL EXPLORATION...... 9 2.1. INTRODUCTION...... 9 2.2. REGOLITH CARBONATE AS A SAMPLING MEDIUM...... 11 2.3. THE REGOLITH ENVIRONMENT IN RELATION TO REGOLITH CARBONATE AND GOLD...... 14 2.4. CALCIUM: CHEMICAL, BIOLOGICAL, AND PHYSICAL CONTROLS IN THE REGOLITH ...... 17 2.5. GOLD: CHEMICAL, BIOLOGICAL, AND PHYSICAL CONTROLS IN THE REGOLITH ...... 20 2.6. REGOLITH CARBONATES AND GOLD: WHAT DO WE KNOW?...... 27 2.7. CONCLUSION ...... 28 METHODOLOGY ...... 29 3.1. INTRODUCTION...... 29 3.2. SAMPLE COLLECTION AND HANDLING ...... 29 3.2.1. Profile sampling...... 30 3.2.2. Regolith carbonate sampling ...... 31 3.3. MODULE 1: SOURCE OF CALCIUM IN REGOLITH CARBONATES ...... 32 3.4. MODULE 2: CALCRETE-GOLD IN THE LANDSCAPE ...... 33 3.5. MODULE 3: GOLD IN THE REGOLITH PROFILE ...... 34 3.5.1. Mass balance analysis ...... 35 3.5.2. Particle-size separation ...... 37 3.5.3. Bulk density...... 42 3.5.4. Measuring the carbonate concentration (calcimetry)...... 43 3.5.5. Density separation ...... 45 3.5.6. Electrical conductivity and pH...... 46 3.5.7. Electron Microscopy...... 46 3.6. SPECIALIST SAMPLE PREPARATION AND ANALYSIS...... 49 3.6.1. Impregnation of in-situ samples...... 50 3.6.2. Petrological thin section preparation ...... 50 3.6.3. Inductively coupled plasma – mass spectrometry (ICP MS)/ optical emission spectrometry (ICP OES) and fire assay / atomic absorption (FAA)...... 50 3.6.4. Instrumental neutron activation analysis (INAA) ...... 50 3.6.5. X-ray diffraction (XRD) and X-ray fluorescence (XRF) ...... 51 SOURCE OF CALCIUM IN REGOLITH CARBONATES ...... 53

i 4.1. CALCIUM IN REGOLITH CARBONATES OF CENTRAL AND SOUTHERN AUSTRALIA: ITS SOURCE AND IMPLICATIONS FOR THE GLOBAL CARBON CYCLE...... 53 4.1.1. Abstract ...... 53 4.1.2. Introduction...... 53 4.1.3. Geology of sample areas ...... 55 4.1.4. Methodology...... 55 4.1.5. Results ...... 58 4.1.6. Discussion ...... 61 4.1.7. Conclusion...... 65 4.2. THE SOURCE OF CALCIUM THROUGH THE REGOLITH PROFILE...... 66 4.2.1. Profile descriptions ...... 66 4.2.2. Strontium isotope variation through the profiles...... 66 4.2.3. Discussion ...... 70 4.3. SYNTHESIS: MOBILITY OF CALCIUM IN SOUTHERN AUSTRALIA ...... 72 CALCRETE-GOLD IN THE LANDSCAPE: REGOLITH-LANDFORM CONTROLS AT TUNKILLIA, SOUTH AUSTRALIA ...... 77 5.1. INTRODUCTION ...... 77 5.2. GEOLOGY OF THE TUNKILLIA AU DEPOSIT AND SURROUNDING REGION ...... 80 5.3. REGOLITH-LANDFORMS AND VEGETATION OF THE TUNKILLIA AREA ...... 81 5.4. PALAEO-LANDSCAPE: HISTORY OF THE TUNKILLIA LANDSCAPE ...... 89 5.5. REGOLITH CARBONATE FEATURES IN THE TUNKILLIA LANDSCAPE ...... 92 5.6. ELEMENT DISPERSION PATTERNS IN THE TUNKILLIA AREA: RESULTS AND DISCUSSION ...... 94 5.6.1. Major elements...... 94 5.6.2. Trace elements...... 95 5.6.3. Rare Earth elements ...... 106 5.6.4. Discussion ...... 108 5.7. SYNTHESIS: LANDSCAPE CONTROLS ON GEOCHEMISTRY ...... 112 5.7.1. Contemporary landscape...... 113 5.7.2. Palaeo-landscape ...... 113 5.7.3. Proximity to mineralisation...... 114 5.8. CONCLUSION...... 119 GOLD IN THE REGOLITH PROFILE: PEDOGENIC CONTROLS AT WHITE DAM, SOUTH AUSTRALIA ...... 121 6.1. INTRODUCTION ...... 121 6.2. GEOLOGY OF THE WHITE DAM AU-CU DEPOSIT AND THE SURROUNDING REGION ...... 122 6.3. REGOLITH-LANDFORMS AND VEGETATION OF THE WHITE DAM AREA...... 126 6.4. WHITE DAM PROFILE 1: DESCRIPTION, PETROLOGY AND ANALYTICAL RESULTS...... 126 6.4.1. Profile 1 description and petrology...... 126 6.4.2. Profile 1 particle-size analysis ...... 134 6.4.3. Profile 1: Bulk density, calcimetry, pH and EC ...... 140 6.4.4. Elemental assay results and trends for Profile 1...... 140 6.5. WHITE DAM PROFILE 2, DESCRIPTION, PETROLOGY AND ANALYTICAL RESULTS ...... 155 6.5.1. Profile 2 description and petrology...... 155 6.5.2. Profile 2 particle-size analysis ...... 160 6.5.3. Profile 2: Bulk density, calcimetry, pH and EC ...... 162 6.5.4. Elemental assay results and trends for Profile 2...... 163 6.6. MASS BALANCE ANALYSIS ...... 177 6.6.1. Tests for uniformity in Profile 2 and selection of parent material...... 178 6.6.2. Mass balance calculations for Profile 2...... 182 6.6.3. Major element mass changes for Profile 2...... 184 6.6.4. Trace and rare earth element mass changes for Profile 2...... 187 6.7. GOLD MORPHOLOGY IN THE WHITE DAM PROFILES ...... 188 6.8. SYNTHESIS: FORMATION OF THE WHITE DAM PROFILES AND IMPLICATIONS FOR GOLD MOBILITY ... 192 6.9. CONCLUSION...... 196 SYNTHESIS ...... 199 7.1. INTRODUCTION ...... 199 7.2. PEDOLOGICAL, GEOCHEMICAL, AND GEOMORPHOLOGICAL EVOLUTION OF AU-IN-CALCRETE ...... 200

ii 7.3. CONCLUSION ...... 206 REFERENCES ...... 209

APPENDIX 1 REGOLITH-LANDFORM UNIT MAPPING CODES...... 231 APPENDIX 2 TUNKILLIA ASSAY RESULTS...... 233 APPENDIX 3 WHITE DAM SAMPLE DECSRIPTION AND PETROLOGICAL NOTES ...... 237 APPENDIX 4 WHITE DAM XRD REPORTS ...... 263 APPENDIX 5 BULK DENSITY AND CALCIMETRY RESULTS FROM WHITE DAM SAMPLES ...... 279 APPENDIX 6 WHITE DAM ASSAY RESULTS ...... 285 APPENDIX 7 WHITE DAM MASS BALANCE RESULTS ...... 295

iii List of figures

FIGURE 1.1: REGOLITH TERMINOLOGY USED IN THIS THESIS (ADAPTED FROM TAYLOR & BUTT, 1998; EGGLETON, 2001; SCHAETZL & ANDERSON, 2005)...... 2 FIGURE 1.2: RELATIONSHIP BETWEEN THESIS CHAPTERS AND RESEARCH MODULES, HIGHLIGHTING THE CHANGE IN SCALE FROM CONTINENTAL TO PROFILE...... 4 FIGURE 2.1: EXAMPLE OF A REGOLITH PROFILE WITH MANY OF THE MAIN REGOLITH CARBONATE MORPHOLOGIES (ROADSIDE CUTTING NEAR SEDAN, SOUTH AUSTRALIA, GDA ZONE 54: 34886ME 6173045MN)...... 10 FIGURE 2.2: PLOTS OF CA, MG AND AU CONCENTRATION V DEPTH (LINTERN, 1989)...... 12 FIGURE 2.3: INTERPRETED DISTRIBUTION OF REGOLITH CARBONATES IN AUSTRALIA, FROM CHEN ET AL. (2002). 13 FIGURE 2.4: COMPONENTS OF THE SOIL ORGANIC MATTER FROM BALDOCK & SKJEMSTAD (1999)...... 16 FIGURE 2.5: RHIZOMORPHS IN CALCAREOUS SAND AT PENNINGTON BAY, KANGAROO ISLAND, SOUTH AUSTRALIA. SIZES RANGE FROM ~5 CM DIAMETER FOR LARGE TREE ROOT (LOWER LEFT) TO FINE < MM SIZE ROOTS...... 19 FIGURE 2.6: GOLD INTERCONVERSION CYCLE, ADAPTED FROM BOYLE (1979)...... 21 FIGURE 3.1: A PREPARED PROFILE READY FOR SAMPLING AND UNDISTURBED SAMPLE COLLECTION, WHITE DAM PROFILE 1, CURNAMONA PROVINCE, SA (PROFILE DEPTH ~ 2.3 M, INSET SCALE BAR 10 CM)...... 32 87 86 FIGURE 3.2: TYPICAL SR/ SR RATIO RANGES FOR THE MAJOR SR RESERVOIRS. ADAPTED FROM STILLE AND SHIELDS (1997)...... 33 FIGURE 3.3: COMPARISON OF PARTICLE SIZE CLASSIFICATION SYSTEMS, ADAPTED FROM SOIL SURVEY DIVISION STAFF (1993) AND THE SIZE FRACTIONS USED IN THIS STUDY...... 38 FIGURE 3.4: PARTICLE-SIZE SEPARATION FLOWCHART FOR METHODS USED IN THIS PROJECT...... 40 FIGURE 3.5: CALCIMETRY SYSTEM USED TO DETERMINE THE CARBONATE PERCENTAGE OF SOIL SAMPLES...... 44 FIGURE 3.6: MINERAL IDENTIFICATION PROCESS USED ON DATA GENERATED BY THE EDXI SOFTWARE IN THIS STUDY...... 48 FIGURE 4.1: INTERPRETED DISTRIBUTION OF REGOLITH CARBONATES IN AUSTRALIA, ADAPTED FROM CHEN ET AL. (2002). NUMBERS REPRESENT SAMPLE LOCATIONS: (1) TANAMI, (2) TUNKILLIA, (3) TIBOOBURRA, (4) OLARY, (5) COBAR, (6) CLARENDON, (7) YILGARN TRANSECT AND (8) NT TRANSECT...... 54 FIGURE 4.2: SR ISOTOPE RATIOS PLOTTED BY LOCATION FOR THE LEACHABLE CA (AND SR) (PLOT A) AND RESIDUE 87 86 FRACTIONS (PLOT B). THE SHADED AREA ON PLOT B REPRESENTS THE EXTENT OF THE SR/ SR RATIOS ON PLOT A. THE BOX PLOT IS CALCULATED FROM ALL VALUES ON THE PLOT AND SHOWS THE 25TH AND 75TH PERCENTILES (SHADED BOX), 10TH AND 90TH PERCENTILES (WHISKERS) AND OUTLIERS (SINGLE POINTS). THE LINE WITHIN THE BOX IS THE MEDIAN VALUE...... 58 87 86 FIGURE 4.3: THE SR/ SR RATIOS OF THE LABILE AND RESIDUE FRACTIONS WITH 1:1 CORRELATION LINE...... 61 FIGURE 4.4: SR ISOTOPE RATIOS FROM THE WA TRANSECT PLOTTED BY DISTANCE FROM THE SOUTHERN COASTAL TOWN OF ESPERANCE TOWARDS THE NORTH...... 61 FIGURE 4.5: PLOT SHOWING THE PERCENTAGE OF SR DERIVED FROM BEDROCK. BEDROCK VALUES USED TO CALCULATE PERCENTAGE WERE: TUNKILLIA 0.8330, TIBOOBURRA AND COBAR 0.7817, OLARY 1.0204, CLARENDON 0.9002, TANAMI AND NT TRANSECT 0.8000 AND YILGARN TRANSECT 0.7807...... 62 FIGURE 4.6: AUSTRALIAN DUST PATHS (ADAPTED FROM BOWLER, 1976; HESSE & MCTAINSH, 2003). SAMPLE LOCATIONS; (1) TANAMI, (2) TUNKILLIA, (3) TIBOOBURRA, (4) OLARY, (5) COBAR, (6) CLARENDON, (7) YILGARN TRANSECT AND (8) NT TRANSECT...... 63 87 86 FIGURE 4.7: SR/ SR RATIOS PLOTTED BY APPROXIMATE DISTANCE FROM THE SOUTHERN CONTINENTAL SHELF MARGIN (KM)...... 65 FIGURE 4.8: PHOTOGRAPH OF THE CLARENDON PROFILE SHOWING SOIL HORIZONS AND SAMPLE LOCATIONS...... 67 FIGURE 4.9: SR ISOTOPE RATIOS PLOTTED BY DEPTH FOR THE LEACHABLE CA (AND SR) (PLOT A) AND RESIDUE 87 86 FRACTIONS (PLOT B). THE SHADED AREA ON PLOT B REPRESENTS THE EXTENT OF THE SR/ SR RATIOS ON PLOT A...... 68 87 86 FIGURE 4.10: THE SR/ SR RATIOS OF LABILE FRACTION BY RESIDUE FRACTION...... 70 FIGURE 4.11: PERCENTAGE OF SR (AND CA) DERIVED FROM REGIONAL BEDROCK AND BASAL RESIDUE BY DEPTH. BEDROCK VALUES WERE 1.0204 FOR WHITE DAM AND 0.9002 FOR CLARENDON (TABLE 4.3). BASAL RESIDUE VALUES WERE 0.7640 AND 0.8553 FOR WHITE DAM PROFILES 1 AND 2 RESPECTIVELY, AND 0.9589 FOR CLARENDON...... 71 FIGURE 4.12: MOBILITY AND INTERACTIONS OF CA IN THE REGOLITH ENVIRONMENT...... 74 FIGURE 5.1: EXTENT OF THE GAWLER CRATON, SOUTH AUSTRALIA, AND LOCATION OF THE TUNKILLIA STUDY AREA...... 78 FIGURE 5.2: EXTENT OF > 10 PPB AU-IN-CALCRETE ANOMALY WITH SAMPLE POSITIONS AND TUNKILLIA MINERALISATION. BACKGROUND IMAGES FROM GOOGLE EARTH 2007...... 79

iv FIGURE 5.3: TOPOGRAPHIC MAP OF THE TUNKILLIA AREA SHOWING THE EXTENT OF THE STUDY AREA, POSITION OF THE >10 PPB AU-IN-CALCRETE ANOMALY, AND AREA OF KNOWN MINERALISATION (SRTM DATA SOURCED FROM JARVIS ET AL., 2006)...... 83 FIGURE 5.4: REGOLITH-LANDFORM MAP OF THE STUDY AREA...... 85 FIGURE 5.5: SOUTHERN TRANSECT LANDFORMS AND REGOLITH: A. EXTENSIVE VEGETATION OVER THE DUNE FIELD; B. CASUARINA PAUPER PARTIALLY BURIED BY MIGRATING DUNE; C. OPEN WOODLAND OF THE DUNE SWALES AND D. SOIL WITH CRYPTOGAM SURFACE CRUST, FROM WESTERN END OF THE TRANSECT; E. UNDERSTORY CHARACTERISED BY MAIREANA SEDIFOLIA AND F. SOIL WITH CALCRETE LAG FROM EASTERN END OF TRANSECT (SCALE BAR 10 CM)...... 87 FIGURE 5.6: CENTRAL TRANSECT LANDFORMS AND REGOLITH: EROSIONAL PLAIN WITH DOMINANT MAIREANA SEDIFOLIA (A) AND SOIL (B) SHOWING MIXED CALCRETE AND SILCRETE LAG; AND DRAINAGE DEPRESSION WITH OPEN WOODLAND (C) AND ASSOCIATED SOIL (D) CONSITING OF FINER SANDS AND SILTS (SCALE BAR 10 CM)...... 88 FIGURE 5.7: NORTHERN TRANSECT LANDFORM AND REGOLITH: SHEET FLOOD FAN DOMINATED BY MAIREANA SEDIFOLIA (A) AND POORLY SORTED SANDY SOIL (B); EXAMPLE OF A SHALLOW DRAINAGE DEPRESSION THAT FEEDS THE EPHEMERAL LAKES (SCALE BAR 10 CM)...... 89 FIGURE 5.8: PERIODS OF PROFILE WEATHERING, DURICRUST FORMATION, AND AEOLIAN ACTIVITY IN SOUTHERN AUSTRALIA, CONTINUAL WEATHERING IS REPRESENTED BY DASHED LINES (ALLEY, 1977; BECKMANN, 1983; BENBOW, 1983; BIRD & CHIVAS, 1988; 1989; 1993; BOURMAN, 1993B; BENBOW ET AL., 1995; PILLANS, 2005; HOU ET AL., 2008)...... 91 FIGURE 5.9: SELECTED MAJOR ELEMENT CORRELATIONS: CAO – SIO2; FE2O3 – K2O; AL2O3 – FE2O3; AND, AL2O3 – K2O...... 96 FIGURE 5.10: DISPERSION OF AL2O3 ALONG THE THREE TRANSECTS SHOWING AN INCREASING CONCENTRATION DOWNSTREAM...... 97 FIGURE 5.11: DISPERSION OF AU ALONG THE THREE TRANSECTS SHOWING HIGH CONCENTRATION OVER “AREA 191” AND ALIGNMENT WITH THE PREVIOUSLY DETERMINED AU-IN-CALCRETE ANOMALY (> 10 PPB)...... 102 FIGURE 5.12: CORRELATION PLOTS OF SELECTED ELEMENTS ASSOCIATED WITH MINERALISATION FE2O3, ZN, AND PB, AND PLOT OF AU VS CAO SHOWING NO CORRELATION...... 103 FIGURE 5.13: DISPERSION OF ZN ALONG THE THREE TRANSECTS SHOWING INCREASING CONCENTRATIONS DOWNSTREAM...... 104 FIGURE 5.14: DISPERSION OF FE2O3 ALONG THE THREE TRANSECTS SHOWING INCREASING CONCENTRATIONS DOWNSTREAM...... 105 FIGURE 5.15: DISPERSION OF CU SHOWING HIGH CONCENTRATION OVER BOTH AREAS OF MINERALISATION...... 106 FIGURE 5.16: CHONDRITE AND PAAS NORMALISED REE PLOTS OF TRANSECT DATA SHOWING ENRICHMENT ALONG THE CENTRAL AND NORTHERN TRANSECTS (TAYLOR & MCLENNAN, 1985; MCLENNAN, 1989). ...111 FIGURE 5.17: POTENTIAL MODELS OF AU DISPERSION FROM MINERALISATION TO THE SURFACE AND ITS INCORPORATION INTO REGOLITH CARBONATES...... 115 FIGURE 5.18: SYMBOLIC OVERVIEW OF THE DRAINAGE PATHWAYS AT TUNKILLIA...... 117 FIGURE 6.1: EXTENT OF THE CURNAMONA PROVINCE (ROBERTSON ET AL., 1998)...... 123 FIGURE 6.2: MINERAL DEPOSITS OF THE OLARY DOMAIN (CONOR, 2004)...... 124 FIGURE 6.3: REGOLITH LANDFORM MAP OF THE WHITE DAM DEPOSIT SHOWING POSITION OF COSTEANS AND SAMPLE PROFILES, FROM BROWN & HILL (2004)...... 127 FIGURE 6.4: PHOTOGRAPHS OF THE TWO WHITE DAM PROFILES SHOWING SOIL HORIZONS AND SAMPLE LOCATIONS...... 129 FIGURE 6.5: RHIZOMORPH AND POWDERY NODULE MORPHOLOGIES OF REGOLITH CARBONATES PRESENT IN THE BK HORIZON...... 132 FIGURE 6.6: SMALL NODULES AND STAINING BY BIRNESSITE WITHIN THE B2 HORIZON...... 132 FIGURE 6.7: MICROPHOTOGRAPHS FROM PROFILE 1: A. WEATHERED FELDSPAR (A1 HORIZON, FOV = 2 MM), B. CRYSTALLITIC B FABRIC (B2 HORIZON, FOV = 2 MM), C. & D. FRACTURED FELDSPAR GRAINS WITH PLANT ROOT (C HORIZON, FOV = 4 MM), E. CLAY CUTANS ON COARSE GRAINS BUT NOT ON VOIDS (A1 HORIZON, FOV = 2 MM), AND F. CALCITE INFILLED VOIDS (BK HORIZON, FOV = 4 MM)...... 133 FIGURE 6.8: QUARTZ VEIN (CIRCLED) THROUGH GNEISS SHOWING PTYGMATIC TYPE FOLDS CONTINUING THROUGH CLAY-RICH VEIN (DASHED LINE)...... 134 FIGURE 6.9: STACKED XRD PLOTS FROM PROFILE 1 OF CLAY-SIZE FRACTION SHOWING REDUCTION IN KAOLIN CONTENT AND INCREASED ILLITE / SMECTITE INTERSTRATIFICATION TOWARDS THE SURFACE...... 136 FIGURE 6.10: PARTICLE SIZE FRACTION AND HEAVY MINERAL CONTENT OF PROFILE 1...... 137 FIGURE 6.11: FESEM BACKSCATTER IMAGES: ZIRCONS FROM THE B2 (A), BK (B), AND 2B2 (C) HORIZONS; ETCHED ILMENITE GRAIN WITH DISSOLUTION FEATURES (D); AND RUTILES FROM A1 (E), BK (F), 2B3 (G) AND TOP OF THE SAPROLITH (H)...... 139 FIGURE 6.12: MAJOR ELEMENT DEPTH PLOTS OF BULK SOIL ASSAYS FOR PROFILE 1...... 142

v FIGURE 6.13: MAJOR ELEMENT DEPTH PLOTS OF SIZE FRACTION ASSAYS OF NA AND FE FOR PROFILE 1...... 144 FIGURE 6.14: TRACE ELEMENT DEPTH PLOTS OF THE BULK AND FINE EARTH SOIL ASSAYS FOR PROFILE 1. SOME SAMPLES WERE BELOW DETECTION LIMITS FOR AS (2 PPM), BI (0.1 PPM), CR (10 PPM), SB (0.2 PPM), AND V (20 PPM)...... 146 FIGURE 6.15: BULK AND SIZE FRACTION DEPTH PLOTS OF AU VS DEPTH FOR PROFILE 1...... 148 FIGURE 6.16: TRACE ELEMENT DEPTH PLOTS OF SIZE FRACTION ASSAYS FOR PROFILE 1. SOME SAMPLES WERE BELOW DETECTION LIMITS FOR AS (2 PPM), BR (1 PPM), CO (5 PPM), CR (10 PPM), HF (1 PPM), AND SB (0.2 PPM)...... 150 FIGURE 6.17: REE DEPTH PLOTS OF THE BULK AND FINE EARTH SOIL ASSAYS FOR PROFILE 1...... 153 FIGURE 6.18: REE DEPTH PLOTS OF SIZE FRACTION ASSAYS FOR PROFILE 1...... 154 FIGURE 6.19: CHONDRITE AND PAAS NORMALISED REES FOR PROFILE 1 (TAYLOR & MCLENNAN, 1985; MCLENNAN, 1989)...... 155 FIGURE 6.20: MICROPHOTOGRAPHS FROM PROFILE 2: A. AND B. ORGANIC PARTICLE WITH CALCITE COATING (B2 HORIZON, FOV A = 12 MM, B = 4 MM), C. CALCITE LAMINATIONS FORMING CAPPING ON LARGE FELDSPAR GRAIN (BK HORIZON, FOV = 4 MM), D. FELDSPAR AND QUARTZ AGGREGATES, NOTE LACK OF COATINGS (B2 HORIZON, FOV = 4 MM)...... 158 FIGURE 6.21: STACKED XRD PLOTS OF THE CLAY-SIZE FRACTION ILLUSTRATING THE BREAKDOWN OF ILLITE AND ITS INTERSTRATIFICATION WITH SMECTITE TOWARDS THE SURFACE...... 159 FIGURE 6.22: TOP OF SAPROLITH (CK HORIZON) SHOWING THE GRADUAL CONTACT WITH THE OVERLYING BK HORIZON AND THE GRADATION INTO A MORE CONSOLIDATED C HORIZON...... 160 FIGURE 6.23: DEPTH PLOTS OF PARTICLE SIZE FRACTIONS AND HEAVY MINERAL CONTENT OF PROFILE 2...... 162 FIGURE 6.24: BACKSCATTER IMAGES: A & B) ZIRCON GRAINS FROM THE A1 AND B2 HORIZONS RESPECTIVELY; C & D) RUTILE GRAINS FROM THE B1 AND BK HORIZONS RESPECTIVELY; E) DISSOLUTION FEATURE ON SURFACE OF ILMENITE GRAIN, DARKER AREAS CONTAIN MORE TIO2; AND, F) GENERAL VIEW OF PREPARED SAMPLE STUB FOR SAMPLE WD3-07 SHOWING HIGH BIOTITE PERCENTAGE...... 164 FIGURE 6.25: MAJOR ELEMENT DEPTH PLOTS OF BULK SOIL ASSAYS FOR PROFILE 2...... 166 FIGURE 6.26: MAJOR ELEMENT DEPTH PLOTS OF SIZE FRACTION ASSAYS OF FE AND NA FOR PROFILE 2...... 167 FIGURE 6.27: TRACE ELEMENT DEPTH PLOTS OF THE BULK AND FINE EARTH SOIL ASSAYS FOR PROFILE 2. SOME SAMPLES WERE BELOW DETECTION LIMITS FOR AS (2 PPM), BI (0.1 PPM), CO (5 PPM), AND SB (0.2 PPM). . 169 FIGURE 6.28: TRACE ELEMENT DEPTH PLOTS OF SIZE FRACTIONS FROM PROFILE 2. SOME SAMPLES WERE BELOW DETECTION LIMITS FOR AS (2 PPM), BR (1 PPM), CS (3 PPM), RB (30 PPM), SB (0.2 PPM), AND ZN (50 PPM)...... 172 FIGURE 6.29: REE DEPTH PLOTS OF THE BULK AND FINE EARTH SOIL ASSAYS FOR PROFILE 2...... 175 FIGURE 6.30: REE DEPTH PLOTS OF SIZE FRACTION ASSAYS FOR PROFILE 2...... 176 FIGURE 6.31: CHONDRITE AND PAAS NORMALISED REES FOR PROFILE 2 (TAYLOR & MCLENNAN, 1985; MCLENNAN, 1989)...... 177 FIGURE 6.32: ZIRCON, RUTILE AND ILMENITE GRAIN COUNTS OF SAND FRACTIONS AND ASSOCIATED RATIOS BY PROFILE DEPTH...... 179 FIGURE 6.33: PLOT OF TI AND ZR CONCENTRATIONS AS DETERMINED BY XRF FOR THE CLAY, FINE AND MEDIUM SAND FRACTIONS, AND BY ICP-OES FOR THE BULK SAMPLES. NOTE: VALUES FOR ZR IN THE 20-53 µM FRACTION HAVE BEEN DIVIDED BY 10...... 180 FIGURE 6.34: RATIOS OF SAND AND SILT FRACTIONS PLOTTED BY PROFILE DEPTH...... 182

FIGURE 6.35: DEPTH PLOTS OF BULK DENSITY (ΡB), BULK DENSITY RATIO (ΡP / ΡW), ZR CONCENTRATION,

ENRICHMENT FACTOR (CZR,W / CZR,P), AND STRAIN (ΕZR,W) FOR PROFILE 2...... 183 FIGURE 6.36: ESTIMATES OF ORIGINAL PROFILE DEPTH AND MASS CALCULATED FROM VOLUMETRIC CHANGES AND ZR CONCENTRATIONS...... 185

FIGURE 6.37: DEPTH PLOTS OF SELECTED MAJOR ELEMENT CONCENTRATIONS, ENRICHMENT FACTOR (CZR,W / CZR,P),

TRANSPORT FUNCTION (τEL,W,Ε(ZR)), AND MASS FLUX CHANGES FOR PROFILE 2...... 186

FIGURE 6.38: DEPTH PLOTS OF CONCENTRATION, ENRICHMENT FACTOR (CZR,W / CZR,P), TRANSPORT FUNCTION

(τEL,W,Ε(ZR)), AND FLUX CHANGES FOR AU AND AG IN PROFILE 2...... 188

FIGURE 6.39: DEPTH PLOTS OF CONCENTRATION, ENRICHMENT FACTOR (CZR,W / CZR,P), TRANSPORT FUNCTION

(τEL,W,Ε(ZR)), AND FLUX CHANGES FOR CU AND AS IN PROFILE 2...... 189

FIGURE 6.40: DEPTH PLOTS OF CONCENTRATION, ENRICHMENT FACTOR (CZR,W / CZR,P), TRANSPORT FUNCTION

(τEL,W,Ε(ZR)), AND FLUX CHANGES FOR CE (LREE), GD (MREE) AND YB (HREE) IN PROFILE 2...... 190 FIGURE 6.41: FESEM MICROPHOTOGRAPHS OF AU GRAINS FROM PROFILE 1. MORPHOLOGY OF AU PARTICLE IN F, SUGGESTS POSSIBLE MICROBIAL INVOLVEMENT...... 191 FIGURE 7.1: PROPOSED MODEL OF AU-IN-CALCRETE ANOMALY FORMATION...... 203 FIGURE 7.2: SOIL DEPTH PROFILE PLOTS FROM BOUNTY AND ZULEIKA SANDS AU DEPOSITS SHOWING AU ENRICHMENT ALIGNED WITH, OR JUST ABOVE THE HIGH CA CONCENTRATION ZONE, EVEN WHEN CA IS VERY LOW (PLOT G) (FROM LINTERN & BUTT, 1993; 1998B)...... 205

vi FIGURE 7.3: MODEL OF BLIND AND TRANSPORTED AU-IN-CALCRETE ANOMALY FORMATION. LATER BURIAL OF THE REMOVED ANOMALY (STEP 3) WOULD OBSCURE EVIDENCE OF UNDERLYING MINERALISATION...... 207

vii List of Tables

TABLE 2.1: STANDARD ELECTRODE POTENTIAL OF AU AND SELECTED COMPOUNDS AT 25˚C (DEAN 1992; LIDE, 2004)...... 21 TABLE 2.2: SUMMARY OF AU DISSOLUTION AND PRECIPITATION CONDITIONS...... 22 TABLE 3.1: SUMMARY OF THE METHODS USED IN THIS RESEARCH. MODULE 1: SOURCE OF CALCIUM IN REGOLITH CARBONATES, MODULE 2: CALCRETE-GOLD IN THE LANDSCAPE: REGOLITH-LANDFORM CONTROLS AT TUNKILLIA, SA, AND MODULE 3: GOLD IN THE REGOLITH PROFILE: PEDOGENIC CONTROLS AT WHITE DAM, SA. (* TASK PERFORMED BY COMMERCIAL LABORATORY)...... 30 TABLE 3.2: SUMMARY OF METHODS AND USES OF SAMPLE MEDIA COLLECTED FOR THIS RESEARCH...... 31 TABLE 3.3: CALCULATED TIMES FOR PARTICLES OF < 2 µM AND < 20 µM DIAMETERS TO SETTLE SELECTED HEIGHTS AT 20˚C...... 41 TABLE 3.4: SOME COMMON MINERALS AND THEIR SPECIFIC GRAVITY (DATA FROM KLEIN & HURLBUT, 1999). ... 45 TABLE 3.5: ANALYSIS METHOD AND THE ELEMENTS MEASURED BY AMDEL LTD...... 51 TABLE 4.1: DETAILS OF SAMPLING AREA AND SAMPLE DESCRIPTIONS...... 57 TABLE 4.2: SAMPLE LOCATIONS AND RESULTS OF SR ISOTOPE ANALYSIS...... 59 87 86 TABLE 4.3: SUMMARY OF SR/ SR RATIOS FOR BEDROCK TYPICAL TO EACH AREA AND THE VALUES USED IN CALCULATING THE PERCENTAGE OF CA DERIVED FROM BEDROCK...... 60 TABLE 4.4: SR ISOTOPE RATIOS FROM PROFILE ANALYSIS...... 69 TABLE 5.1: EXAMPLES OF MINERALISATION LOCATED WITH THE GAWLER CRATON, SOUTH AUSTRALIA...... 80 TABLE 5.2: MORPHOLOGY, AU AND CAO ASSAYS AND LOCATION OF THE REGOLITH CARBONATE SAMPLES...... 93 TABLE 5.3: CONCENTRATIONS OF THE MAJOR ELEMENTS BY TRANSECT, “AREA 191”, AND TOTALS. DATA INCLUDE RANGE (%), MEAN AND 2SE...... 95 TABLE 5.4: SIGNIFICANT CORRELATIONS (-0.8 > R > 0.8) WITH MAJOR ELEMENTS FOR THE FULL DATASET AND INDIVIDUAL TRANSECTS...... 98 TABLE 5.5: CONCENTRATIONS OF THE TRACE ELEMENTS BY TRANSECT, “AREA 191”, AND TOTALS. DATA INCLUDE ASSAY RANGE (PPM, EXCEPT AU PPB), MEAN AND 2SE...... 99 TABLE 5.6: SIGNIFICANT CORRELATIONS (-0.8 > R > 0.8) WITH TRACE ELEMENTS FOR THE FULL DATASET AND INDIVIDUAL TRANSECTS...... 100 TABLE 5.7: CONCENTRATIONS OF THE REES BY TRANSECT, “AREA 191”, AND TOTALS. DATA INCLUDE ASSAY RANGE (PPM), MEAN AND 2SE...... 107 TABLE 5.8: VALUES FOR CORRELATIONS TO WHICH -0.8 > R > 0.8 FOR THE REES...... 108 TABLE 6.1: STRATIGRAPHY AND LITHOLOGICAL SUMMARY OF THE WILLYAMA SUPERGROUP (OLARY DOMAIN), DIRECT RELATIONSHIP BETWEEN SOME FORMATIONS IS UNCERTAIN (DASHED LINES) (ADAPTED FROM CONOR, 2000; CONOR & FANNING, 2001; CONOR, 2004; PAGE ET AL., 2005; CONOR, 2006A)...... 125 TABLE 6.2: HORIZON PROPERTIES OF WHITE DAM PROFILE 1...... 130 TABLE 6.3: RESULTS FROM PARTICLE SIZE ANALYSIS OF SAMPLES FROM PROFILE 1...... 135 TABLE 6.4: SUMMARY OF HEAVY MINERAL GRAIN COUNT ANALYSIS FOR PROFILE 1...... 138 TABLE 6.5: PH, EC, CACO3, AND BULK DENSITY FOR PROFILE 1...... 140 TABLE 6.6: ELEMENTS THAT WERE AT OR BELOW DETECTION FOR > 20% OF SAMPLES FROM PROFILE 1. NOTE: ELEMENTS IN RED WERE ONLY BELOW DETECTION FOR EITHER THE PEDOLITH OR SAPROLITH...... 141 TABLE 6.7: HORIZON PROPERTIES OF WHITE DAM PROFILE 2...... 156 TABLE 6.8: RESULTS FROM PARTICLE SIZE ANALYSIS OF SAMPLES FROM PROFILE 2...... 161 TABLE 6.9: SUMMARY OF HEAVY MINERAL GRAIN COUNT ANALYSIS FOR PROFILE 2...... 163 TABLE 6.10: PH, EC, CACO3, AND BULK DENSITY FOR PROFILE 2...... 165 TABLE 6.11: ELEMENTS THAT WERE AT OR BELOW DETECTION FOR > 20% OF SAMPLES FROM PROFILE 2. NOTE: ELEMENTS IN RED WERE ONLY BELOW DETECTION FOR EITHER THE PEDOLITH OR SAPROLITH...... 165 TABLE 6.12: COMPARISON OF MEAN ± 2SE (N = 8) FOR ZR/TI, AND ZIRCON, RUTILE, AND ILMENITE RATIOS...... 181 TABLE 6.13: SUMMARY OF MEAN ±2SE (N=8) FOR THE SAND FRACTION RATIOS...... 181 TABLE 6.14: MAJOR ELEMENT MASS FLUX GAINS OR LOSSES BY HORIZON AND IN ORDER OF MAXIMUM GAIN/LOSS...... 187

viii Abstract

Regolith carbonate, especially when indurated (calcrete), has been widely adopted as a sampling medium by many Australian Au exploration companies. Rapid uptake of the medium in geochemical exploration programs, following its reported success in the South Australia Challenger Au deposit discovery, has resulted in poorly constrained sampling methodology with many inconsistencies. Results have therefore been equivocal. This study of regolith carbonates and their association with Au will improve this situation. Three aspects of regolith carbonate development and association with Au are investigated. These are based on variable spatial scales, ranging from the southern Australian continent, to local area, to individual profile.

On a continental scale, regolith carbonates cover extensive areas of southern Australia. The primary component, Ca, is sourced from mineral weathering or atmospheric sources. Through the use of Sr isotopes to provide a surrogate expression for Ca sources, the source was identified as > 90% atmospheric or marine derived. A uniform inland signature is identified, which is due to the continual recycling and mixing of marine derived Ca with minimal bedrock input. An external Ca source means that Ca does not have a direct relationship with Au, which is locally sourced from mineralised areas.

On a local scale, a Au-in-calcrete anomaly extending over 20 km2 and lying over both mineralised (Tunkillia Au prospect) and barren bedrock was investigated. Regolith-landform mapping and geochemistry was used to further identify the zone of elevated Au-in-calcrete. The zone was found to correspond spatially with palaeo- and contemporary drainage systems that currently flow into ephemeral lakes. Geochemistry of the area shows that the majority of elements have been transported and enriched along these systems. This dispersion pattern and its contemporary landscape expression is complicated by dune fields over mineralisation that partially cover the palaeo-drainage. Millions of dollars have been spent drilling this anomaly with no significant mineralisation found beyond the discrete Tunkillia mineralized zones, yet with the aid of regolith-landform mapping an explanation of the anomaly spatial pattern and dispersion pattern has been provided at very low cost.

On the profile scale, two regolith carbonate profiles from the White Dam Au-Cu prospect were analysed in detail. Mass balance calculations revealed chemical gains and losses for the soil horizon and total profile. The investigation quantified the extensive external Ca input and revealed the position and size of the Au particles. Gold in the profile prior to regolith carbonate development is concentrated at the top of what is presently the regolith carbonate horizon as calcite precipitation in void spaces reduces permeability. Ongoing calcite precipitation up the profile locks in the Au, resulting in a Au-in-calcrete anomaly.

Exposure of Au-enriched calcrete horizons to chemical and physical weathering results in decomposition of the material. This material can then be transported in the form of surface lag, which may settle on top of existing and still developing regolith carbonates to form new Au-in-calcrete anomalies that are unrelated to underlying bedrock.

The formation of Au-in-calcrete anomalies in relation to landscape processes is demonstrated. Additional information on landscape setting, gathered while sampling, can therefore improve interpretation of regolith carbonate geochemistry. Exploration companies that take time to understand the landscape setting in this way and react accordingly, can therefore expect improved results.

ix Originality statement

This work contains no material which has been accepted for the award of any other degree or diploma in any university or other tertiary institution and, to the best of my knowledge and belief, contains no material previously published or written by another person, except where due reference has been made in the text.

I give consent to this copy of my thesis, when deposited in the University Library, being made available for loan and photocopying, subject to the provisions of the Copyright Act 1968.

I also give permission for the digital version of my thesis to be made available on the web, via the University’s digital research repository, the Library catalogue, the Australasian Digital Theses Program (ADTP) and also through web search engines, unless permission has been granted by the University to restrict access for a period of time.

Robert Dart

x Acknowledgements

This thesis and the research undertaken to complete it, is the result of a journey I started back in 1999 when I enrolled for a degree in Applied Geology at UniSA. To get from that point to this completed thesis has involved numerous people who offered advice and assistance along the way. I herby acknowledge and thank everyone who helped, advised, criticised, and encouraged me during this journey.

I start by acknowledging the support and teaching provided by the geology staff at UniSA, especially: Bob Wiltshire, Jim Jago, Mark Bishop, Ian Clark, John Cann, and Sol Buckman.

Scholarship and research funding was provided by CRC LEME and The University of Adelaide. Minotaur Exploration Ltd. provided financial support for the Tunkillia sample assays. I hereby thank these organisations and their staff, especially: Dennis Gee, Steve Rogers, and Tony Belperio.

CRC LEME provided many benefits beyond financial, not least of which were the interactions between the various bodies, including PIRSA, Australian National University, and Geoscience Australia. The opportunity to discuss my work through informal meetings and formal presentations was greatly appreciated. Furthermore, I have made some great friends along the way. I therefore thank the staff of these organisations, including: John Keeling, Alan Mauger, Adrian Fabris, Justin Gum, Malcolm Sheard, Mark McGeough, Todd McKenzie, Frank Reith, Lisa Worrall, Colin Pain, Matilda Thomas, Keith Scott, D C “Bear” McPhail, Ian Roach, Ken McQueen, David Gray, and Mehrooz Aspandiar.

I thank Alasdair Cooke of Exco Resources for access to White Dam, and Michael Wilson of Helix and Tony Belperio of Minotaur for access to Tunkillia. I also thank Barry van der Stelt, Richard Flint, and Richard Hill of Minotaur for sharing their knowledge of the Tunkillia area.

Support from laboratory technicians was invaluable to this research. I therefore thank David Bruce and Colin Rivers. I thank John Terlet, Peter Self and Angus Netting along with the other staff at Adelaide Microscopy for assistance in operating the SEM. I also thank the general support staff of the Geology and geophysics department, especially John Stanley, David Ladd, and Chris Hill. Whilst thanking support staff, I also include Jane Wannan from the Library, for tracking down those difficult articles.

I shared many “interesting” hours with fellow students, which included serious discussion and debate, social drinking and eating, and probably most importantly, support and advice. Here is my attempt to list you all, but if I have missed you, I apologise: Karen Hulme, Anna Petts, Ian Lau, Aija Mee, Jessie Davy, Nathan Reid, Luke Tylkowski, Paul Wittwer, Jack Lowrey, Mike Hatch, Michael Nemanis, David Haberlah, Justin Payne, Ben Wade, Rian Dutch, David Mitchell, and Aaron Brown.

I thank the lecturing and research staff of the University of Adelaide, geology and geophysics department for their support and advice along the journey: Graham Heinson, John Foden, Nick Direen, Richard Hillis, Martin Hand, Alan Collins, Vic Gostin, Andreas Schmidt- Mumm, Liz Campbell, Yvonne Bone, Rowl Twidale, Martin Williams, Galen Halverson, David Giles, Ian Plimer, and John Cooper. This list is not complete without including my supervisors Karin Barovich, Steve Hill and David Chittleborough, who deserve a special mention. Thank you Karin for being my primary supervisor, for putting up with my many

xi missed deadlines without a fuss, for providing advice when needed, and for support through the difficult times. I thank David for his pedological input into a geological research topic, which allowed the use of pedological techniques such as particle-size-analysis to be used in a geological context. Finally I thank Steve who came on board part way through, but made up for it with his never ending enthusiasm of the landscape and regolith processes. But most of all I thank you for the friendship, general support and the belief that I would one day actually finish, when at times I could not see this myself. Thank you.

I now thank the most important people in my life, my family. You put up with a lot more than I would have ever expected you to. I start by thanking Michael and Simon, who had just started school when I started my undergrad and have now just graduated from year 12. During this time I have spent many hours away or in isolation. I apologise for this and hope that I was always there when you needed me. I give a very special thank you to my wife, Carol. You have stood next to me and supported my choices, even to the extent of taking up full time work. It has not always been easy and we have had our ups and downs, but we are still together, and better still we are still talking to each other. Thank you Carol for your support, understanding, love, friendship, and, most of all, patience.

I also thank my dad, Mervyn, and “in-laws”, Ann and Keith, who despite their misgivings on why I should give up a good career and how could I support my family, still stood by my decision. Thanks guys for your support not only to me but for the family.

Finally, I dedicate this work to my mum, Barbara. You were always proud of your four sons and their achievements and I know that you would have been so pleased for me to have got this far. My only regret is that you are not here to share this time with me. I therefore dedicate this thesis to you. Thank you for being the best mum a son could ask for.

Thanks guys

Robert

xii Definition of abbreviations and acronyms

AAS Atomic Absorption Spectroscopy AMIRA Australian Mineral Industries Research Association Ltd CEC Cation exchange capacity CRC LEME Cooperative Research Centre for Landscape Environments and Mineral Exploration CSIRO Commonwealth Scientific and Industrial Research Organisation EDX (or EDS) Energy Dispersive X-ray Spectroscopy FA Fulvic acid FEGSEM Field Emission Gun Scanning Electron Microscope HA Humic acid ICP-MS Inductively Coupled Plasma – Mass Spectrometer ICP-OES Inductively Coupled Plasma – Optical Emission Spectrometer INAA Instrumental neutron activation analysis LGM Last glacial maximum PIRSA Primary Industries and Resources, South Australia PPL Plane polarised light REE Rare Earth Elements LREE Light rare earth elements ( La, Ce, Pr, & Nd) MREE Medium rare earth elements (Sm, Eu, Gd, Tb, Dy, & Ho) HREE Heavy rare earth elements (Er, Tm, Yb, & Lu) RLU Regolith Landform Unit RO Reverse osmosis purified water TIMS Thermal Ionisation Mass Spectrometer XPL Crossed polarisers XRD X-Ray Diffraction XRF X-Ray Fluorescence

xiii Publications and conference abstracts derived from this thesis research

Peer reviewed journal articles

Dart R. C., Barovich K. M., Chittleborough D. J. & Hill S. M. 2007. Calcium in regolith carbonates of central and southern Australia: Its source and implications for the global carbon cycle. Palaeogeography, Palaeoclimatology, Palaeoecology, 249, 322-334.

Refereed Conference abstracts

Dart R. C., Hill S. M., Barovich K. M., & Chittleborough D. J. 2007. Improving the reliability of Au-in-calcrete anomalies through the use of regolith-landform mapping and detailed assay analysis. In 5th Sprigg Symposium, November 2007: Regolith, Mineral Deposits and Environment, edited by Cooper, B. J. & Keeling J. L., Geological Society of Australia Abstracts No. 87, pp. 7-10.

Dart R. C., Barovich K. M., Chittleborough D. J. & Hill S. M. 2006. The source of Calcium in regolith carbonates of Australia and the implications to the global carbon cycle. In 9th Australasian Environmental Isotope Conference and 2nd Australasian Hydrogeology Research Conference, Integrating research and innovation, edited by Simmons, C., Love, A., Krull, E. and Pillar, T., pp. 61-62.

Dart R. C., Chittleborough D. J., Barovich K. M. 2006. Gold distribution through the regolith profile: examples from the White Dam prospect, Olary, South Australia. In Regolith 2006 – Consolidation and Dispersions of Ideas, edited by R.W. Fitzpatrick and P. Shand, CRC LEME, Perth, Western Australia, pp. 48-52.

Dart R. C., Barovich K. M. & Chittleborough D. 2006. Gold-calcium association and the development of the regolith carbonate profile. In Australian Earth Sciences Convention 2006, convention handbook, edited by D. Denham, RESolutions Resources & Energy Services, Osborne Park, Western Australia, pp. 77.

Dart R. C., Barovich K. M. & Chittleborough D. 2005. Pedogenic carbonates, strontium isotopes and their relationship with Australian dust processes. In Regolith 2005 - Ten Years of CRC LEME, edited by I. C. Roach. CRC LEME, pp. 64-66.

Dart R. C., Barovich K. M. & Chittleborough D. 2005. Distribution and origin of regolith carbonates in southern Australia. In From tropics to tundra; 22nd international geochemical exploration symposium; program and abstracts, Promaco Conventions, Canning Bridge, Western Australia, pp. 120.

Dart R. C., Wittwer P. D., Barovich K. M., Chittleborough D. & Hill S. M. 2004. Strontium isotopes as an indicator of the source of calcium for regolith carbonates. In Regolith 2004, edited by I. C. Roach. CRC LEME. pp. 67-70.

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