frome uranium province, south australia · frome uranium. province. eromanga. basin (mesozoic) lake...

IAGOD, Adelaide 2010

Roger Skirrow, E. Bastrakov, A. Cross, S. Jaireth, A. Schofield, S. van der Wielen

Frome uranium province, South Australia:

Systems analysis and potential for major basin-hosted uranium deposits

IAGOD, Adelaide 2010

Frome uranium province – southern Lake Eyre Basin and Eromanga Basin(?)

FROME URANIUMPROVINCE

EROMANGABASIN (MESOZOIC)

LAKE EYREBASIN (CENOZOIC)

SEDIMENT-HOSTED URANIUMDEPOSIT

IAGOD, Adelaide 2010

DEPOSITIONAL GRADIENTS(Q5)

PRESERVATION

SOURCES of Metals, fluids,ligands, sulfur(Q3)

ENERGY(Q4)

MINERAL SYSTEM TIME WINDOWMINERAL SYSTEM TIME WINDOW

PERMEABILITY ARCHITECTURE (Q2, Q4)Event 2

PERMEABILITY ARCHITECTURE (Q2, Q4)

Event 1Craton Province District Deposit Micro

SCALE

TIME

(Q1)

MINERAL SYSTEM – geological components(all components are a product of geodynamic and tectonic evolution, ‘Q1’)

(From Skirrow, 2009)[Q1-Q5 are the Five Questions of the pmd*CRC]

IAGOD, Adelaide 2010

Part A

Sources of energy, uranium and fluids

IAGOD, Adelaide 2010

From SKM (2009, PER for Heathgate Resources)

Mt Painter Inlier

Lake Frome

SCHEMATIC SECTION: PREVIOUS MODELS

BeverleyFour Mile

AB

A B

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GEOLOGY TOPOGRAPHY(From Surface Geology of Australia, 2009)

Mt Painter Inlier

(SRTM)

Curnamona Province

Mesozoic

Proterozoic

Paleozoic

Cenozoic

U-channel on DEM backdropU-channel on DEM backdrop

RADIOMETRICS

High-uranium potential sources High-uranium potential sources

IAGOD, Adelaide 2010

Mt Painter Inlier – U source?Since ~4 MaSince ~4 Ma

(oblique view looking northwest; U-channel radiometrics over DTM)

N

Four Mile

Beverley

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Previous models and shortcomings• Widely held views –

– Uranium source for both Beverley and Four Mile was Mt Painter Inlier

– Beverley and Four Mile formed recently within the modern fluid flow regime (i.e., from MPI towards Lake Frome)

• However, Four Mile ‘too close’ to basin margin for a ‘conventional’ sandstone-uranium model of formation (supported by numerical modelling), and deposit ages not known.

Explanation requiressystem perspective

IAGOD, Adelaide 2010

Beverley Sands

Cadna-owie

Formation

Eyre Fm

Willawortina Fm

Namba FmNamba Fm

0

10

20

30

40

50

60

70

80

90

100

110

120

130

Ma

1.

2.

3.

Stratigraphy Descript. Tectonics Deepweathering

PotentialU system

uplift

uplift

uplift

Callabonna Sub-basinof Lake Eyre BasinCallabonna Sub-basinof Lake Eyre Basin

Eromanga BasinEromanga Basin

• 3 periods of regional uplift.• At least 2 deep weathering

events with potential to release & store uranium from Prot basement.

• Permeable seds at 4+ strat levels, ± reductants.

• Potentially 3 episodes of uranium mineralisation since late Mesozoic.

Constraints on uplift from: Foster et al. (1994), Mitchell et al. (2002), Célérier et al. (2005), Quigley et al. (2006).

Constraints on weathering from: Pillans (2006), Smith et al. (2009).

From Skirrow (2009)

Mineral system evolution and alternative model

IAGOD, Adelaide 2010

Part B

Permeability architecture• Sandy units in Mesozoic (e.g., Cadna-owie

Fm) and Cenozoic formations (e.g., Eyre Fm, Beverley Sands)

• Paleovalleys and paleochannels• Fault geometry

IAGOD, Adelaide 2010

EL 5 and 6

LegendSpringsDeposits (OZMIN)Uranium OccurrencesRedox Drill HolesNeogene PaleochannelsPaleogene Paleochannels

OxidisedMixed Redox StateReduced

LegendSpringsDeposits (OZMIN)Uranium OccurrencesRedox Drill HolesNeogene PaleochannelsPaleogene Paleochannels

OxidisedMixed Redox StateReduced

Top of Namba Formation

Paleovalleys/channels marked by reductants? • Drill logs searched• Reduced zones = Fe2+

minerals, reduced-C, reduced-S, “black”, etc

• Oxidised zones = Fe3+

minerals, “red”, etc• Gridded in 3D• North-south paleovalleys in

Namba Fm as well as Eyre?

IAGOD, Adelaide 2010

From Teasdale et al. (2001 – Arrowie SEEBASE)

Depth to pre-Paleozoic basement Basement-involved faultsGAB mound springs (Draper & Jensen, 1976)GAB mound springs (Draper & Jensen, 1976)Four Mile UFour Mile U

Beverley UBeverley U

Honeymoon UHoneymoon U Honeymoon UHoneymoon U

FAULT ARCHITECTURE

N

0.50 lat

Eocene paleochannelsEocene paleochannels

Possiblepaleovalleydirection

IAGOD, Adelaide 2010

PERMEABILITY ARCHITECTUREOF URANIUM SYSTEMS

• Paleovalleys / channels in both Eyre Fm and Namba Fm trend broadly south to north in the region, controlled by reactivated faults.

• Four Mile and Beverley paleovalleysmay have trended N or NNE, not E or SE.

From McConachy et al. (2006)

HeathgateResources (1998)

N

1 km

Beverley depositN

From Heathgate

(1998)

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Part C

Model of 3 uranium episodes, and potential for major deposits

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FROME URANIUM PROVINCE EVOLUTION

Paleogeographic reconstruction from Langford et al. (1995)

IAGOD, Adelaide 2010

FROME URANIUM PROVINCE EVOLUTION

IAGOD, Adelaide 2010

FROME URANIUM PROVINCE EVOLUTION

IAGOD, Adelaide 2010

FROME URANIUM PROVINCE EVOLUTION

IAGOD, Adelaide 2010

FROME URANIUM PROVINCE EVOLUTION

IAGOD, Adelaide 2010

Conclusions

1) Frome uranium province: Cenozoic Lake Eyre Basin ± Mesozoic Eromanga Basin.

2) Three episodes of potential uranium mineralisation since late Mesozoic.

3) South-to-north paleovalley/channel systems, controlled by long-lived faults.

4) Potential for larger deposits in north of Frome uranium province within paleovalleys.

IAGOD, Adelaide 2010

Alternative model:

• At least three periods of uplift from late Mesozoic, recorded by geological observations (Celerier et al., 2005), apatite thermo-chronology (Foster et al., 1994; Mitchell et al., 2002), 10Be studies of erosion rates (Quigley et al., 2006).

• Deep weathering in 3 episodes during/since late Mesozoic (Pillans, 2006; Smith et al., 2009).

• Potential for 3 episodes of uranium mobilisation, with groundwater flow driven by regional basement uplift.

• Uranium, sediment and water transport from south (or southwest) to north (or northeast), to satisfy mass-balance requirements of reductants.

• Or mobile reductant at Four Mile?

IAGOD, Adelaide 2010

• Proterozoic Mount Painter Inlier and Curnamona Province

• Sediments derived from these sources

High-uranium potential sources

Radiometrics U-channelon DEM backdropRadiometrics U-channelon DEM backdrop

From Radiometrics Map of Australia (Geoscience Australia)over SRTM DEM data

IAGOD, Adelaide 2010

GAB mound springs (Draper & Jensen, 1976)

First vertical derivative of TMI(McConachy et al., 2006)

139o 140o

30o

31o

Beverley deposit

From Teasdale et al. (2001)

Depth to pre-Paleozoic basement

IAGOD, Adelaide 2010

From SKM (2009, PER for Heathgate Resources)

(Brugger et al., 2005)

Mt Painter Inlier Lake Frome

SCHEMATIC SECTIONS: PREVIOUS MODELS

Generalised model for roll-front style sandstone uranium deposits

BeverleyFour Mile

Generalised model for roll-front style sandstone uranium deposits

IAGOD, Adelaide 2010

EromangaBasin

NorthernQueensland

Pine CreekOrogen

PatersonProvince

Gawler Craton& Curnamona

Province

Geoscience Australia uranium study areas

Uranium resources of Australia

Lake Frome study area