Platinum mineralisation potential of the Longwood Igneous Complex, New Zealand

Cowden, Alistair; Ruddock, R.; Reay, A.; Nicolson, P.; Waterman, P.; Banks, M. J.

doi:10.1007/bf01162690

Cited by 14 publications

(22 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This result is consistent with the observations of Cowden et al (1990) who were also unable to resolve discrete PGE minerals at the micrometre scale in mineralised surface samples. Drill core samples with anomalous PGE values (e.g.…”

Section: Platinum-group Minerals(?) and Sulfidessupporting

confidence: 82%

“…Turnbull & Allibone 2003). PGE mineralogy of the nearby Orepuki placer material included isoferroplatinum, sperrylite, cooperiteÁ braggite, and iridosmineÁosmiridium (Cowden et al 1990). This relatively S-poor assemblage is analogous to that found in the nearby mafic to ultramafic Greenhills Complex (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…most As B10 ppm and majority B2 ppm, Bi mostly B0.2 ppm, Pb mostly B4 ppm, Sn mostly B0.5 ppm and Te 50.25 ppm). Cowden et al (1990) reported values of up to 3.0 ppm Pt and 3.3 ppm Pd in olivine gabbro float in the southern part of the Longwood Tops, as well as nearby anomalous soils with up to 0.47 ppm Pt. This region was targeted by Anzex using DDH3 and DDH4 (Fig.…”

Section: Mafic and Ultramafic Rocksmentioning

confidence: 99%

“…The same groups are recognised in drill core, although gabbronorite is uncommon and restricted to local intervals in DDH 1 and DDH2. Drill holes 3 and 4, approximately 100 m apart, were targeted at a zone that Cowden et al (1990) had reported strongly anomalous Pt 'Pd values in surface float (Ford Figure 2 Aeromagnetic image of the Longwood Range region, enhanced from original data of Anzex Resources (Ford 1999) by re-processing, and showing the locations of Anzex drill holes DDH1Á4 and outline of bush-free area on Longwood Tops. Inset shows the simplified geology of Longwood Tops from Rombouts (1994). 1999) (Fig.…”

Section: General Geologymentioning

confidence: 99%

“…Challis & Lauder (1977) reported traces of 'platinum and gold' in anorthosite and troctolite in the southern part of the Longwood Range. Mineralisation potential led to subsequent exploration by Amoco Minerals (Hay 1989) and Sigma Resources, with the latter company locating strongly anomalous Pt and Pd values in rock float and soil (Cowden et al 1990). A more detailed exploration program by Anzex Resources Limited (Anzex) in 1998Á99 again demonstrated anomalous Pt and Pd values in soil and surface rock samples in the southern Longwood Range, with c. 2.5 km of diamond drill core from four drill holes containing several intervals up to a few metres long of anomalous Pt' Pd (c. 100Á1000 ppb) values (Ford 1999).…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Mafic and ultramafic rocks, and platinum mineralisation potential, in the Longwood Range, Southland, New Zealand

Ashley

Craw

MacKenzie

et al. 2012

New Zealand Journal of Geology and Geophysics

View full text Add to dashboard Cite

Intrusive rocks in the Longwood Range represent a component of the Permian Brook Street Terrane. They include diffusely layered, cumulate-textured olivine gabbro, troctolite, and gabbro, and gradations into non-cumulate gabbro and gabbronorite. Volumetrically small ultramafic layers occur (plagioclase wehrlite), and thin veins of felsic rocks ranging from quartz diorite to trondhjemite. Primary olivine, plagioclase, clinopyroxene, and subordinate orthopyroxene and hornblende are commonly altered or metamorphosed to amphiboles, minor spinel, magnetite, chlorite, biotite and clinozoisite, and serpentine in olivinerich rocks. Accessory primary Ti-bearing magnetite and ilmenite occur, and trace Cr-magnetite is characteristic of olivine-rich rocks. Trace pyrrhotite, chalcopyrite, pentlandite, and pyrite could reflect equilibrated late magmatic, and alteration-derived phases. Key petrochemical characteristics of the rock suite are high Mg, Al, Ca, and Sr contents, and low alkali, LILE, and sulfur contents. Platinum and Pd are locally enriched in drill-hole intercepts, but zones appear unrelated to rock type, magnetic properties, or to S, Cu, Ni, Cr, or Au values. Local platinum group element (PGE) enrichment in altered rocks implies metamorphic and/or hydrothermal redistribution. Pervasive PGE enrichment in Longwood rocks is an indicator of potential 'fertility', but evidence is currently lacking for the precipitation of primary stratiform PGE accumulations from a sulfide liquid saturated magma.

show abstract

Section: Platinum-group Minerals(?) and Sulfidessupporting

confidence: 82%

Section: Discussionmentioning

confidence: 99%

Section: Mafic and Ultramafic Rocksmentioning

confidence: 99%

Section: General Geologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Mafic and ultramafic rocks, and platinum mineralisation potential, in the Longwood Range, Southland, New Zealand

Ashley

Craw

MacKenzie

et al. 2012

New Zealand Journal of Geology and Geophysics

View full text Add to dashboard Cite

show abstract

Cooperite and braggite from the Bushveld Complex: implications for the miscibility gap and identification

Merkle

Verryn

2003

Miner Deposita

View full text Add to dashboard Cite

Analyses of the Pt-Pd±Ni sulphides cooperite, braggite, and vysotskite reported from worldwide occurrences seem to imply a continuum of compositions between vysotskite and cooperite, with no obvious miscibility gap. This is contrary to the experimentally confirmed miscibility gap between cooperite and braggite, and the established compositional gap between co-existing cooperite and braggite from the Merensky Reef. Although the only unambiguous way of distinguishing between cooperite and braggite is to obtain structural information through X-ray diffraction or equivalent techniques, most identification of Pt-Pd±Ni sulphides is based on microanalytical techniques due to the small grain size of most platinum-group minerals. Ni contents also have to be considered because a classification based on the Pt/Pd ratio alone can be very misleading. Naming of Pt-Pd±Ni sulphide compositions with high Pt contents based on qualitative or semiquantitative analyses should be avoided. Natural PtPd±Ni sulphides which project into the compositional gap (established by experimental work) cannot be named without supporting structural information. Compositions of grains, which plot inside the gap, are considered to be metastable and to result from the loss of Pd through interaction with hydrothermal fluids.Keywords Braggite AE Cooperite AE Pt-Pd-Ni-S AE Miscibility gap AE Bushveld AE South Africa Recent experimental investigations of the system PtS- PdS-NiS (Verryn and Merkle 2000, 2002) confirmed the presence of a miscibility gap between cooperite and braggite and a continuous solid solution series between braggite and vysotskite. Contrary to the experimentally confirmed miscibility gap between cooperite and braggite, a compilation of analyses reported in the literature from worldwide occurrences seems to imply a continuum of compositions between vysotskite and cooperite with no obvious gap (Fig. 1). This contribution focuses on the reasons for the discrepancy between experiments and natural occurrences. The question also arises of which criteria to use for identification of minerals inside the experimentally established miscibility gap. The data baseA compilation of published analyses from the literature (for sources see caption of Fig. 1) was used to evaluate the miscibility gap between cooperite and braggite and the problem of identifying some natural Pt-Pd-Ni sulphides. The database of 592 microprobe analyses from Miner Deposita (2003) 38: 381-388

show abstract

Compositional variations and morphological evolution in platinum beach placers, southern New Zealand

et al. 2012

View full text Add to dashboard Cite

Platinum mineralisation potential of the Longwood Igneous Complex, New Zealand

Cited by 14 publications

References 6 publications

Mafic and ultramafic rocks, and platinum mineralisation potential, in the Longwood Range, Southland, New Zealand

Mafic and ultramafic rocks, and platinum mineralisation potential, in the Longwood Range, Southland, New Zealand

Cooperite and braggite from the Bushveld Complex: implications for the miscibility gap and identification

Compositional variations and morphological evolution in platinum beach placers, southern New Zealand

Contact Info

Product

Resources

About