|Title||Rapid geochemical imaging of rocks and minerals with handheld laser induced breakdown spectroscopy (LIBS)|
|Author||Lawley, C J M; Somers, A M; Kjarsgaard, B A|
|Source||Journal of Geochemical Exploration 106694, 2020., https://doi.org/10.1016/j.gexplo.2020.106694|
|Alt Series||Natural Resources Canada, Contribution Series 20200361|
|Media||paper; on-line; digital|
|File format||pdf; html|
|Province||Northwest Territories; Nunavut|
|Lat/Long WENS||-115.0000 -107.0000 67.1667 64.3333|
|Subjects||Science and Technology; geochemistry; spectroscopy; Slave Craton; machine learning|
|Illustrations||location maps; tables; diagrams; graphs|
|Program||Targeted Geoscience Initiative (TGI-5) Gold ore systems|
|Released||2020 11 11|
|Abstract||Geochemical imaging is a powerful tool for unravelling the complex geological histories of rocks and minerals. However, its applications has until recently been restricted to research applications in a
lab environment due to the cost and size of conventional instrumentation, long analysis times, and extensive sample preparation for some methods. Herein we present a rapid geochemical imaging method for rocks and minerals using handheld LIBS.
Analyzes were completed directly on sawed drill core surfaces for a suite of kimberlite-hosted mantle xenoliths (Jericho and Muskox kimberlite intrusions, Canada). Semi-automated LIBS spectral processing following a new open-source workflow allows
stitching of multiple small-area maps (each approximately 3 x 3 mm) to produce cm-scale geochemical images of altered mantle xenolith samples. We demonstrate with open-source machine learning tools how qualitative LIBS spectral data can be converted
to Feature-Of-Interest (FOI) maps to distinguish mineralogy, including differentiating primary mantle minerals from high (Cr diopside) - and low-T (kelephytic pyrope garnet) phase alteration. Our results further demonstrate that the resolution of
handheld LIBS-based geochemical imaging is sufficient to map mineral overgrowths, microscale veinlets, and grain boundaries lined with hydrothermal alteration minerals. The LIBS approach is particularly sensitive for mapping the microscale
distribution of elements with low atomic number (eg, Li and Na), which is challenging with other handheld technologies. |
|Summary||(Plain Language Summary, not published)|
The Targeted Geoscience Initiative (TGI) -5 program develops new models and methods to improve mineral exploration targeting in challenging environments.
Here we present a new method for mapping the composition of rocks and minerals. The new method is rapid and requires very little sample preparation, which is important for mineral in remote areas that may not be able to access conventional research
laboratories. We apply the new method to a suite of rocks from the past-producing Jericho diamond mine.