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


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

FROME URANIUMPROVINCE

EROMANGABASIN (MESOZOIC)

LAKE EYREBASIN (CENOZOIC)

SEDIMENT-HOSTED URANIUMDEPOSIT


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]


Part A

Sources of energy, uranium and fluids


From SKM (2009, PER for Heathgate Resources)

Mt Painter Inlier

Lake Frome

SCHEMATIC SECTION: PREVIOUS MODELS

BeverleyFour Mile

AB

A B


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


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

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

N

Four Mile

Beverley


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


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


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


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?


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


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)


Part C

Model of 3 uranium episodes, and potential for major deposits


FROME URANIUM PROVINCE EVOLUTION

Paleogeographic reconstruction from Langford et al. (1995)


FROME URANIUM PROVINCE EVOLUTION


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.


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?


• 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


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


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


EromangaBasin

NorthernQueensland

Pine CreekOrogen

PatersonProvince

Gawler Craton& Curnamona

Province

Geoscience Australia uranium study areas

Uranium resources of Australia

Lake Frome study area

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

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