Remobilization of PGE in podiform chromitite in the Coolac Serpentinite Belt, Southeastern Australia

Franklin, B. J.; Marshall, Brian D.; Graham, Ian T.; McAndrew, John

doi:10.1080/08120099208728030

Cited by 8 publications

(4 citation statements)

References 14 publications

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“…The more common Fe-Mg chlorite is usually formed at low temperatures (ca. <300 • C) [79], but the pinkish chrome chlorite in this study seems to be formed at a relatively higher temperature like~300 • C as chromium in podiform chromitites and associated mafic/ultramafic rocks would be mobilized over a range of 300-500 • C [34]. This is consistent with the estimation of fluid temperatures of at least 300 • C in the Luobusa listwanites [27].…”

Section: Formation Of the Hydrothermal Minerals And Source Of The Fluidssupporting

confidence: 79%

Timing of Secondary Hydrothermal Alteration of the Luobusa Chromitites Constrained by Ar/Ar Dating of Chrome Chlorites

Guo

et al. 2018

Minerals

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Chrome chlorites are usually found as secondary phases formed by hydrothermal alteration of chromite deposits and associated mafic/ultramafic rocks. Here, we report the 40 Ar/ 39 Ar age of chrome chlorites separated from the Luobusa massive chromitites which have undergone secondary alteration by CO 2 -rich hydrothermal fluids. The dating results reveal that the intermediate heating steps (from 4 to 10) of sample L7 generate an age plateau of 29.88 ± 0.42 Ma (MSWD = 0.12, plateau 39 Ar = 74.6%), and the plateau data points define a concordant inverse isochron age of 30.15 ± 1.05 Ma (MSWD = 0.08, initial 40 Ar/ 36 Ar = 295.8 ± 9.7). The Ar release pattern shows no evidence of later degassing or inherited radiogenic component indicated by an atmospheric intercept, thus representing the age of the hydrothermal activity. Based on the agreement of this hydrothermal age with the~30 Ma adakitic plutons exposed in nearby regions (the Zedong area, tens of kilometers west Luobusa) and the extensive late Oligocene plutonism distributed along the southeastern Gangdese magmatic belt, it is suggested that the hydrothermal fluids are likely related to the~30 Ma magmatism. The hydrothermal fluid circulation could be launched either by remote plutons (such as the Sangri granodiorite, the nearest~30 Ma pluton west Luobusa) or by a similar coeval pluton in the local Luobusa area (inferred, not found or reported so far). Our results provide important clues for when the listwanites in Luobusa were formed.

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Section: Formation Of the Hydrothermal Minerals And Source Of The Fluidssupporting

confidence: 79%

Timing of Secondary Hydrothermal Alteration of the Luobusa Chromitites Constrained by Ar/Ar Dating of Chrome Chlorites

Guo

et al. 2018

Minerals

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“…The belts are emplaced into a variety of early and middle Palaeozoic strata and are exposed over a total linear distance of 230 km (Franklin et al 1992). They vary in size from small lenses less than 5m in length, up to a single large body which crops out continuously for some 56km and are composed of variably foliated harzburgite and dunite.…”

Section: Regional Geological Settingmentioning

confidence: 99%

“…wehrlite, lherzolite) as well as talc-carbonate bodies and rodingite dykes. Podiform chromitite bodies have been found in the CSB and WSB with associated minor platinum-group element (PGE) mineralisation (Franklin et al 1992).…”

Section: Regional Geological Settingmentioning

confidence: 99%

“…This suggests that the chromium for their formation is derived from chromite within the podiform chromitite bodies and not from either accessory chromite grains or chromium-bearing silicates from within the partially serpentinised harzburgite hostrock. Thus, during the formation of the chromium-bearing garnets, chromium from within the chromitite must have been at least locally remobilised (Franklin et al, 1992) and then incorporated within the garnet molecule during its growth. Other components required for the formation of the garnets (such as Al, Mg and Fe) may have also been released from chromite grains at this time.…”

Section: General Statementmentioning

confidence: 99%

See 1 more Smart Citation

The occurrence and origin of well-crystallised uvarovite garnet from the podiform chromitite deposits of south-eastern New South Wales

Graham¹,

Colchester²

1995

Journal and Proceedings of the Royal Society of New South Wales

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Chromian garnets occur within three podiform chromitite deposits in south-eastern N.S.W. Fourteen new analyses of these garnets are presented in this paper and these reveal that the garnets are either uvarovite or chromian grossular in composition. These analyses, along with analyses of uvarovite garnets from other world occurrences, suggest that there is no distinct relationship between the composition of uvarovite garnets and the geological setting in which they occur. Although the composition of the chromium-bearing garnets from the two deposits which are examined in some detail in this paper are quite different, their environment of formation was similar. All of the Cr-bearing garnets have formed during calcium metasomatism congruent with localised remobilisation of chromium.

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Chemistry and mineralogy of podiform chromitite deposits, southern NSW, Australia: a guide to their origin and evolution

Graham

Franklin

Marshall

1996

Mineralogy and Petrology

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Remobilization of PGE in podiform chromitite in the Coolac Serpentinite Belt, Southeastern Australia

Cited by 8 publications

References 14 publications

Timing of Secondary Hydrothermal Alteration of the Luobusa Chromitites Constrained by Ar/Ar Dating of Chrome Chlorites

Timing of Secondary Hydrothermal Alteration of the Luobusa Chromitites Constrained by Ar/Ar Dating of Chrome Chlorites

The occurrence and origin of well-crystallised uvarovite garnet from the podiform chromitite deposits of south-eastern New South Wales

Chemistry and mineralogy of podiform chromitite deposits, southern NSW, Australia: a guide to their origin and evolution

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