|Title||In situ LA-ICP-MS systematics for quantitative volatile trace-element measurement in sulphide minerals: from developing methodology to its application in the case study of massive sulphide deposits of the
Bathurst Mining Camp, Canada|
|Author||Soltani Dehnavi, A; Lentz, D R; McFarlane, C R M; McClenaghan, S H|
|Source||New Brunswick Exploration, Mining and Petroleum conference program and abstracts volume; 2014 p. 92|
|Links||Online - En ligne|
|Alt Series||Earth Sciences Sector, Contribution Series 20130537|
|Meeting||New Brunswick 2014 Exploration, Mining and Petroleum conference; Fredericton; CA; November 2-4, 2014|
|Media||paper; on-line; digital|
|NTS||21O/01; 21O/02SE; 21O/02NE; 21O/07SE; 21O/07NE; 21O/08; 21O/09; 21O/10SE; 21O/10NE; 21P/04; 21P/05; 21P/12|
|Lat/Long WENS||-66.6667 -65.5000 47.7500 47.0000|
|Subjects||geochemistry; mineralogy; volcanogenic deposits; sulphides; sulphide deposits; trace element analyses; electromagnetic induction; mass spectrometer analysis; analytical methods; Bathurst Mining
Geoscience Initiative (TGI-4) |
|Abstract||Laser Ablation ICP-MS analysis on sulphide minerals is challenging: polyatomic interferences, scarcity of suitable external standards, and variations in laser-target interactions among standards and
unknowns all need to be accounted for. Improved analytical protocols described here include an assessment of optimized ablation conditions, including laser sampling and energy density. Analyses are carried out in spot mode in which a beam size of 24
or 33?m was selected on the basis of textural criteria, thickness of the polished sections, and necessary analytical precision and detection limits. The laser was operated at 4 or 3 Hz repetition rate with the laser fluence held at ~1 mJ per cm2.
Sulphide minerals, because of their high thermal conductivity, are susceptible to melting during ablation at high fluence. The energy of the system should, therefore, be carefully adjusted to prevent melting of samples and increase the reliability of
the data. Presently, USGS-Sulphide Standard MASS- 1 external standard reference materials is the most accessible standard for LAICP- MS of sulphide minerals. In this study, calibration was performed using external standard MASS-1. Tl values (which
are not published for MASS-1) are obtained by calculation of the data versus NIST 610. In addition, synthetic sulphide standards (University of Adelaide, Australia) have been used to demonstrate the reproducibility and efficiency of our methodology.
For the purpose of calculations, Fe was selected as the internal standard for quantification of pyrite, marcasite, chalcopyrite, arsenopyrite, pyrrhotite, and tetrahedrite, whereas Zn and Pb were selected for sphalerite and galena, respectively. Data
reduction and calculation was done using the Iolite™ 2.5 Trace Element Data Reduction Scheme. The goal of this research was to establish a method for reliable quantification of the volatile trace-element suite (As, Cd, Hg, In, Sb, Tl) in sulphides.
Because of its high sensitivity, the LA-ICP-MS method allows the detection of volatile trace elements at sub-ppm level, significantly better than detection limits obtained from other micro-analytical techniques. Lack of any especial sample
preparation (only thin section) and cost efficiency for examining a large number of grains make this methodology appropriate in academic and industrial applications. Integrated mineralogical and geochemical studies of sulphide mineral assemblages are
completed for the representative massive sulphide deposits of the Bathurst Mining Camp. This data will contribute to our understanding of the massive sulphide mineralization systems and will be useful in developing the exploration vectoring tools
(volatile trace-element halo dispersions) within and around massive sulphide systems in poly-deformed terranes. |