Meta-evaporite sequence, exhalative chemical sediments and associated rocks in the Proterozoic Willyama Supergroup, South Australia: implications for metallogenesis

Cook, Nick; Ashley, P. M.

doi:10.1016/0301-9268(92)90102-t

Cited by 69 publications

(36 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…δ 34 S values of barite mineralisation within the study area (6.8‰ to 16.3‰ CDT) are inconsistent with those of Late Palaeoproterozoic seawater given in Strauss (1993) with 18‰ to 25‰, supporting a nonmarine character of the lower Willyama basin as suggested in Cook and Ashley (1992) or Lottermoser and Ashley (1996). Mixing of the reduced, exhalative fluid with the oxidised, sulphate bearing Willyama basin water triggered the precipitation of barite and iron-oxides.…”

Section: Interpretation and Discussionmentioning

confidence: 44%

“…Sedimentation in the Willyama half-graben was suggested to be diachronous as rifting of the graben commenced in the western Olary Domain with initial deposition in a lacustrine or shallow marine environment, including possible Sabkhas (Cook and Ashley, 1992), and deepening upwards in the sequence. The Willyama Supergroup in the Olary Domain is subdivided, from bottom to top, into the Curnamona Group, Saltbush Group and Strathearn Group (Conor and Preiss, 2008, see Fig.…”

Section: Regional Geologymentioning

confidence: 98%

See 1 more Smart Citation

The Mt. Mulga barite–magnetite–copper–gold mineralisation, Olary Domain, South Australia

Griessmann

Mumm

Seifert

et al. 2010

Journal of Geochemical Exploration

View full text Add to dashboard Cite

Section: Interpretation and Discussionmentioning

confidence: 44%

Section: Regional Geologymentioning

confidence: 98%

The Mt. Mulga barite–magnetite–copper–gold mineralisation, Olary Domain, South Australia

Griessmann

Mumm

Seifert

et al. 2010

Journal of Geochemical Exploration

View full text Add to dashboard Cite

“…Such a meta-evaporitic fluid origin finds support in the presence of abundant F-bearing talc (cf. Cook and Ashley 1992;Garnier et al 2004) and in the halogen ratios of fluid inclusions in quartz and S 1 -overprinting hematite from hematitic veins (Lüders et al 2005). Also, Ti in hematite, with some hundreds micrograms per gram to a few wt% Ti (Table 4 ESM ;andCabral et al 2003, 2006), implies highly saline fluids because the solubility of rutile dramatically increases in F-rich brines (Rapp et al 2010).…”

Section: Discussionmentioning

confidence: 99%

Talc mineralisation associated with soft hematite ore, Gongo Soco deposit, Minas Gerais, Brazil: petrography, mineral chemistry and boron-isotope composition of tourmaline

et al. 2011

View full text Add to dashboard Cite

Talc mineralisation occurs as hematite-talc schist between soft hematite ore and dolomitic itabirite at Gongo Soco, Quadrilátero Ferrífero of Minas Gerais, Brazil. The hematite-talc schist and soft hematite have a prominent tectonic foliation of tabular hematite. Tabular hematite without preferential orientation is superimposed on the tectonic foliation. The talcose schist is enriched in F and has a constant Fe/S ratio. Electron-microprobe analyses indicate trace amounts of S in different generations of hematite. The whole-rock Fe/S ratio possibly represents sulfate S from hematite-hosted fluid inclusions. Fluid inclusions in foliation-overprinting hematite and chlorite geothermometry from talcose rocks suggest, respectively, temperatures from <200°C to~300°C. Tourmaline, a rarely observed mineral in the hematite-talc schist, belongs to the alkali group and falls in the dravite compositional field. Boron-isotope determinations of tourmaline crystals, using secondary ion mass spectrometry, vary from −20‰ to −12‰ δ 11 B. This compositional isotopic range and the tourmaline chemical composition suggest a meta-evaporitic origin. A non-marine evaporitic setting is the most likely source of acidic, highly oxidising fluids, which resulted in the abundant F-bearing talc and the presence of otherwise immobile Ti in hematite. Oxidising brines were channelled along shear zones and converted dolomitic itabirite into the Gongo Soco soft hematite and the talc mineralisation. The latter is envisaged as the hydrothermal wall-rock alteration of dolomitic itabirite, which gave rise to the soft hematite ore.

show abstract

“…11,12). Silicic tuffs have been recorded to be diagenetically Na-metasomatized in alkaline evaporitic lake environments by reaction with Na-rich brines (Ratterman & Surdam, 1981;Cook & Ashley, 1992). If the albite schists were of such an origin, they would likely display trace element patterns different from those of the mudstones (Vanhanen, 2001;Bjørklykke et al, 1987).…”

Section: Origin Of Mudstones and Albite Schistsmentioning

confidence: 99%

The Petäjäskoski Formation, a new lithostratigraphic unit in the Paleoproterozoic Peräpohja Belt, northern Finland

Kyläkoski¹,

Hanski²,

Huhma³

2012

Bull Geol Soc Finland

View full text Add to dashboard Cite

This paper gives the first description of a newly-recognized, basin-wide metasedimentary unit in the Paleoproterozoic (~2.4-1.9 Ga) Peräpohja Belt, northern Finland. The unit, which is named the Petäjäskoski Formation (PFm) after the single location where the rocks are known to be exposed, is situated stratigraphically in the middle part of the Kivalo Group between the quartzites of the >2.22 Ga Palokivalo Formation and the mafic volcanic rocks of the ~2.1 Ga Jouttiaapa Formation.The bulk of the PFm comprises phlogopitic-sericitic and albitic schists with abundant hematite as a diagnostic feature. Quartzite and dolomite interbeds are common. Based on drillcore and geophysical data, the succession is several hundreds of meters thick. The unit has prograde, chiefly lower greenschist facies mineral assemblages and, though being commonly intensely deformed, shows well-preserved sedimentary structures that imply deposition in shallow-water to subaerial environments. Based on the original lithological features, the Petäjäskoski Formation can be defined as a claystone-siltstone-sandstone-dolostone association. On the geochemical and stratigraphic basis, the albite schists likely represent albitized equivalents of the micaceous claystones and siltstones. They are intercalated with stratabound collapse breccias, up to tens of meters in thickness, with clasts composed mainly of bordering albite schist.A mafic sill intruding the Petäjäskoski Formation yielded a U-Pb zircon age of 2140 ± 11 Ma. The older, c. 2220 Ma, differentiated sills are not known to reach the stratigraphic level of the Petäjäskoski Formation and hence, the depositional age of the PFm sediments can be bracketed between c. 2220 and 2140 Ma. Detrital zircon grains dated from a quartzitic sample from the PFm show an Archean (c. 2650-3470 Ma) provenance.The moderate to high MgO (~6-13 wt.%), K 2 O (~3-8 wt.%) and FeO tot (8-15 wt.%) contents, low CaO and Na 2 O contents, and abundant phlogopite and hematite make the mica schists unique among the metasedimentary rocks of the Finnish Karelian supracrustal belts. These features together with the abundance of dravititic tourmaline, the presence of pseudomorphic nodules potentially after gypsum and anhydrite, deposition under shallow-water conditions, and albitization and brecciation of the sedimentary strata suggest an evaporitic depositional environment.The Petäjäskoski Formation, a new lithostratigraphic unit in the Paleoproterozoic Peräpohja Belt, northern Finland

show abstract

Meta-evaporite sequence, exhalative chemical sediments and associated rocks in the Proterozoic Willyama Supergroup, South Australia: implications for metallogenesis

Cited by 69 publications

References 50 publications

The Mt. Mulga barite–magnetite–copper–gold mineralisation, Olary Domain, South Australia

The Mt. Mulga barite–magnetite–copper–gold mineralisation, Olary Domain, South Australia

Talc mineralisation associated with soft hematite ore, Gongo Soco deposit, Minas Gerais, Brazil: petrography, mineral chemistry and boron-isotope composition of tourmaline

The Petäjäskoski Formation, a new lithostratigraphic unit in the Paleoproterozoic Peräpohja Belt, northern Finland

Contact Info

Product

Resources

About