the genesis of the wonmunna marra mamba iron ore …smedg.org.au/marshall regolith marra mamba...

Regolith Enrichment of the Wonmunna Marra Mamba Iron Ore Deposits of the Hamersley

Region, Western Australia

Angela MarshallSupervisor Dr Solomon Buckman

University of Wollongong

Iron OreMount Whaleback

Mount Tom Price

Aim

to describe the nature of the iron mineralisation at Wonmunna and

determine the processes responsible for Fe-enrichment

WONMUNNAHamersley Province, Pilbara

Wonmunna

Banded Iron Formation (BIF)

SILICA

Fe

FeSILICA

SILICA

Ore Types

Unenriched BIF

Martite-goethite ore

Microplaty-hematite ore

Enrichment ProcessesHypogene Model1. warm, reduced fluids leach silica2. Oxidisation ( hot meteoric oxidising fluids)3. Microplaty hematite formed in carbonate matrix4. Late stage supergene leaching

Taylor et al., (2001)

Supergene – Metamorphic Model

1. Supergene processes for martite-goethite ore2. Burial metamorphism upgrades this to

microplaty-hematite ore

Morris (1985)

Regolith ProcessesRamanaidou (2009)

Field work and mapping

Petrography

10 x, plane polarized light 10 x, crossed polarized light

Reflected light microscopy

Distribution of minerals downhole, NMM deposit Hole 150

0% 20% 40% 60% 80% 100%

0-2

2-4

4-6

6-8

8-10

10-12

12-14

14-16

16-18

18-20

20-22

22-24

24-26

26-28

28-30

30-32

32-34

34-36

36-38

38-40

40-42

42-44

44-46

46-48

48-50

50-52

52-54

54-56

56-58

58-60

60-62

62-64

64-66

66-68

68-70

70-72

Dep

th (m

)

Composition %

HematiteGoethiteMagnetiteQuartzKaolinite

MineralogyXRD

Conclusion• Relationship with the current surface and

regolith development.

• Microplaty hematite in the Marra Mamba Iron Formation at Wonmunna

• Regolith enrichment model for Wonmunna: oxidation, leaching, goethitisation dehydration of goethite mpl-H

• Implications for exploration models