Three-dimensional textural and quantitative analyses of orogenic gold at the nanoscale
| Autor: | M. Lehtonen, Aki Kallonen, Raimo Lahtinen, Jussi-Petteri Suuronen, Ferenc Molnár, Julie Villanova, Hugh O’Brien, Mohammad Sayab |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Arsenopyrite
010504 meteorology & atmospheric sciences Orientation (computer vision) Mineralogy Synchrotron radiation Geology engineering.material 010502 geochemistry & geophysics 01 natural sciences Matrix (geology) Beamline visual_art engineering visual_art.visual_art_medium Pyrite Tomography Microscale chemistry 0105 earth and related environmental sciences |
| Zdroj: | Geology. 44:739-742 |
| ISSN: | 1943-2682 0091-7613 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|