Three-dimensional textural and quantitative analyses of orogenic gold at the nanoscale

M. Sayab, J. P. Suuronen, F. Molnár, J. Villanova, A. Kallonen, H. O'Brien, R. Lahtinen, M. Lehtonen

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11 Citations (Scopus)

Abstract

Ore textures provide direct clues for tracking ore-forming processes. In this regard, most of our knowledge is generally based on two-dimensional (2-D) image analyses, leaving a considerable gap in comprehending three-dimensional (3-D) in-situ textural settings. Recent advances in lab-based and synchrotron radiation-based X-ray computed microtomography and nanotomography have made it possible to visualize and quantify rock volumes in a 3-D space. In this study, we first analyzed microscale textures in oriented drill cores from the world-class Suurikuusikko orogenic gold deposit of northern Finland using lab-based X-ray computed microtomography. The technique revealed a kinematic history and a number of in-situ 3-D quantitative aspects including size, shape, spatial distribution, and geometrical orientation of arsenopyrite and pyrite in a highly altered host-rock matrix. For 3-D nanotomography, the experimental procedure known as holotomography was adopted. Individual arsenopyrite crystals were separated and scanned with voxel sizes ranging from 50 nm to 150 nm using the X-ray nanoprobe beamline (ID16B) at the European Synchrotron Radiation Facility, France. This ultrahigh-resolution technique illustrated the 3-D distribution of micron- to nanoscale gold inclusions, mostly associated with primary rutile or along secondary microfractures inside arsenopyrite. The workflow, from micro- to nanotomography, outlined in this study offers an indispensable new technique in quantifying and characterizing 3-D textural settings of ores, which is otherwise impossible with conventional 2-D imaging devices. The method can also be highly useful in evaluating the amenability of ores to treatment with different processing options.

Original languageEnglish
Pages (from-to)739-742
Number of pages4
JournalGeology
Volume44
Issue number9
DOIs
Publication statusPublished - Sep 1 2016

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ASJC Scopus subject areas

  • Geology

Cite this

Sayab, M., Suuronen, J. P., Molnár, F., Villanova, J., Kallonen, A., O'Brien, H., Lahtinen, R., & Lehtonen, M. (2016). Three-dimensional textural and quantitative analyses of orogenic gold at the nanoscale. Geology, 44(9), 739-742. https://doi.org/10.1130/G38074.1