Defining IOCG signatures through compositional data analysis: A case study of lithogeochemical zoning from the Olympic Dam deposit, South Australia

Dmitrijeva, Marija; Ehrig, Kathy; Ciobanu, Cristiana L.; Cook, Nigel J.; Verdugo-Ihl, Max R.; Metcalfe, Andrew

doi:10.1016/j.oregeorev.2018.12.013

Cited by 30 publications

(12 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For analyses on the nanoSIMS 50L, the seven detectors were carefully tuned to the desired isotopes and grains of interest were presputtered, then mapped (50 × 50 µm raster area, 50 pA ion current, D1 = 2, ES = 2, AS = 0, 512 × 512 pixels (px), 3 planes, 5 ms/px, effective beam diameter ≈ 400 nm). Following this round of mapping, the instrument was retuned to six different isotopes and one redundant isotope, usually 54 Fe (for comparison and alignment between runs), and the grains were mapped a second time (50 × 50 µm raster area, 250 pA ion current, D1 = 2, ES = 2, AS = 0, 512 × 512 px, 5 or 6 planes, 5 ms/px, effective beam diameter ≈ 700 nm). A similar procedure was used for the nanoSIMS 50, although most grains were mapped only once (50 x 50 µm raster area, 2 pA ion current, D1 = 2, ES = 2, AS = 2, 512 × 512 px, 1-3 planes, 15 ms/px, egun on, effective beam diameter ≈ 400 nm).…”

Section: Methodsmentioning

confidence: 99%

“…Identifying and characterizing all components within ore-forming hydrothermal fluids may aid in reconstructing ore formation and alteration profiles, and for defining the geochemical signature of the deposit [54]. To the metallurgist, greater interest lies in the ability of nanoSIMS to track trace amounts of potentially economic elements, including Co, Ni, V, In, and REE during various stages of ore processing.…”

Section: Penalty Elementsmentioning

confidence: 99%

See 1 more Smart Citation

Detection of Trace Elements/Isotopes in Olympic Dam Copper Concentrates by nanoSIMS

et al. 2019

Self Cite

View full text Add to dashboard Cite

Many analytical techniques for trace element analysis are available to the geochemist and geometallurgist to understand and, ideally, quantify the distribution of trace and minor components in a mineral deposit. Bulk trace element data are useful, but do not provide information regarding specific host minerals—or lack thereof, in cases of surface adherence or fracture fill—for each element. The CAMECA nanoscale secondary ion mass spectrometer (nanoSIMS) 50 and 50L instruments feature ultra-low minimum detection limits (to parts-per-billion) and sub-micron spatial resolution, a combination not found in any other analytical platform. Using ore and copper concentrate samples from the Olympic Dam mining-processing operation, South Australia, we demonstrate the application of nanoSIMS to understand the mineralogical distribution of potential by-product and detrimental elements. Results show previously undetected mineral host assemblages and elemental associations, providing geochemists with insight into mineral formation and elemental remobilization—and metallurgists with critical information necessary for optimizing ore processing techniques. Gold and Te may be seen associated with brannerite, and Ag prefers chalcocite over bornite. Rare earth elements may be found in trace quantities in fluorapatite and fluorite, which may report to final concentrates as entrained liberated or gangue-sulfide composite particles. Selenium, As, and Te reside in sulfides, commonly in association with Pb, Bi, Ag, and Au. Radionuclide daughters of the 238U decay chain may be located using nanoSIMS, providing critical information on these trace components that is unavailable using other microanalytical techniques. These radionuclides are observed in many minerals but seem particularly enriched in uranium minerals, some phosphates and sulfates, and within high surface area minerals. The nanoSIMS has proven a valuable tool in determining the spatial distribution of trace elements and isotopes in fine-grained copper ore, providing researchers with crucial evidence needed to answer questions of ore formation, ore alteration, and ore processing.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Penalty Elementsmentioning

confidence: 99%

Detection of Trace Elements/Isotopes in Olympic Dam Copper Concentrates by nanoSIMS

et al. 2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…Hematite from the ore breccias, whether within clasts or the matrix, displays a variety of textures and geochemical signatures but the earliest hematite is oscillatory-and sectorial-zoned with respect to U, W, Sn and Mo [54]. This 'granitophile signature' is present throughout the strike and depth of the orebody and is clearly recognized from multivariate statistical analysis of a large lithogeochemical dataset [55]. Such hematite can also be reliable and accurately dated [46].…”

Section: Geological Background and Sample Selectionmentioning

confidence: 99%

Silician Magnetite: Si–Fe-Nanoprecipitates and Other Mineral Inclusions in Magnetite from the Olympic Dam Deposit, South Australia

et al. 2019

Self Cite

View full text Add to dashboard Cite

A comprehensive nanoscale study on magnetite from samples from the outer, weakly mineralized shell at Olympic Dam, South Australia, has been undertaken using atom-scale resolution High Angle Annular Dark Field Scanning Transmission Electron Microscopy (HAADF STEM) imaging and STEM energy-dispersive X-ray spectrometry mapping and spot analysis, supported by STEM simulations. Silician magnetite within these samples is characterized and the significance of nanoscale inclusions in hydrothermal and magmatic magnetite addressed. Silician magnetite, here containing Si–Fe-nanoprecipitates and a diverse range of nanomineral inclusions [(ferro)actinolite, diopside and epidote but also U-, W-(Mo), Y-As- and As-S-nanoparticles] appears typical for these samples. We observe both silician magnetite nanoprecipitates with spinel-type structures and a γ-Fe1.5SiO4 phase with maghemite structure. These are distinct from one another and occur as bleb-like and nm-wide strips along d111 in magnetite, respectively. Overprinting of silician magnetite during transition from K-feldspar to sericite is also expressed as abundant lattice-scale defects (twinning, faults) associated with the transformation of nanoprecipitates with spinel structure into maghemite via Fe-vacancy ordering. Such mineral associations are characteristic of early, alkali-calcic alteration in the iron-oxide copper gold (IOCG) system at Olympic Dam. Magmatic magnetite from granite hosting the deposit is quite distinct from silician magnetite and features nanomineral associations of hercynite-ulvöspinel-ilmenite. Silician magnetite has petrogenetic value in defining stages of ore deposit evolution at Olympic Dam and for IOCG systems elsewhere. The new data also add new perspectives into the definition of silician magnetite and its occurrence in ore deposits.

show abstract

“…Analogous to the clan of IOCG systems, which are known to display elevated concentrations of many elements (Groves et al 2010), the manifestation of the Acropolis IOCG signature is multi-element ( Figure 5). The U-W-Sn-Mo signature in hematite at Olympic Dam (Verdugo-Ihl et al, 2017) is recognised in geochemical studies as a distinct W-Mo-Sn subset besides the dominant Fe, Cu, Au association in the IOCG signature obtained from PCA analysis (Dmitrijeva et al, 2019). Although Acropolis is deficient in terms of Au (> 70% of values are below the minimum detection limit) and contains geochemically anomalous, but low concentrations of Cu, it demonstrates a mineralisation signature analogous to that at Olympic Dam, with high loadings of W, Sn, Sb, U, Th and REE (Cluster 3), albeit at trace concentrations.…”

Section: Discussionmentioning

confidence: 99%

Mineralization signatures of the magnetite-dominant Acropolis prospect, Olympic Dam IOCG district, South Australia

Dmitrijeva

Ciobanu

Ehrig

et al. 2019

ASEG Extended Abstracts

Self Cite

View full text Add to dashboard Cite

Defining IOCG signatures through compositional data analysis: A case study of lithogeochemical zoning from the Olympic Dam deposit, South Australia

Cited by 30 publications

References 42 publications

Detection of Trace Elements/Isotopes in Olympic Dam Copper Concentrates by nanoSIMS

Detection of Trace Elements/Isotopes in Olympic Dam Copper Concentrates by nanoSIMS

Silician Magnetite: Si–Fe-Nanoprecipitates and Other Mineral Inclusions in Magnetite from the Olympic Dam Deposit, South Australia

Mineralization signatures of the magnetite-dominant Acropolis prospect, Olympic Dam IOCG district, South Australia

Contact Info

Product

Resources

About