Large scale multi-element imaging of geological samples using LIBS

presentation, poster

en

Elemental mapping of light (Li, Be, B, F) and trace elements in large-area geological samples represents an analytical challenge. Increased interest in Li and rare-element deposits showed a need for reliable detection and mapping of light elements, that can be problematic for several analytical methods. One of the possible solutions is a laser-induced breakdown spectroscopy (LIBS) combined with sophisticated data processing (Limbeck et al. 2021; Pořízka et al. 2018). We studied four large-area (ca. 8⨯8 cm) samples from two rare-element Be-rich granitic pegmatites with moderate contents of Li (Mar1A, Maršíkov, Czech Republic) and high contents of Li+B (Ra9 property, Yukon, Canada). Cross-sections from host rock to the pegmatite evolved center were used for direct multi-element mapping. From the obtained LIBS data, 2D maps of individual elements of interest were produced (incl. Li and Be). Afterwards the data we used for advanced statistical algorithms to elucidate mutual relationship of individual elements and provide unsupervised clustering of similar spectral responses. This led to cluster images manifesting the distribution of individual matrices (i.e., minerals). The study demonstrates very good applicability of LIBS for detection and mapping of major (Si, Al, Fe, Mg, Mn, Ca, Na), light elements (Li, Be, B, F), and trace elements (Ge, Ga, Cu, Zn, Ti, Sr, Ba) in pegmatites, discerning their specific geochemical signatures during magmatic, metasomatic, and hydrothermal stage of the rock evolution.

Elemental mapping of light (Li, Be, B, F) and trace elements in large-area geological samples represents an analytical challenge. Increased interest in Li and rare-element deposits showed a need for reliable detection and mapping of light elements, that can be problematic for several analytical methods. One of the possible solutions is a laser-induced breakdown spectroscopy (LIBS) combined with sophisticated data processing (Limbeck et al. 2021; Pořízka et al. 2018). We studied four large-area (ca. 8⨯8 cm) samples from two rare-element Be-rich granitic pegmatites with moderate contents of Li (Mar1A, Maršíkov, Czech Republic) and high contents of Li+B (Ra9 property, Yukon, Canada). Cross-sections from host rock to the pegmatite evolved center were used for direct multi-element mapping. From the obtained LIBS data, 2D maps of individual elements of interest were produced (incl. Li and Be). Afterwards the data we used for advanced statistical algorithms to elucidate mutual relationship of individual elements and provide unsupervised clustering of similar spectral responses. This led to cluster images manifesting the distribution of individual matrices (i.e., minerals). The study demonstrates very good applicability of LIBS for detection and mapping of major (Si, Al, Fe, Mg, Mn, Ca, Na), light elements (Li, Be, B, F), and trace elements (Ge, Ga, Cu, Zn, Ti, Sr, Ba) in pegmatites, discerning their specific geochemical signatures during magmatic, metasomatic, and hydrothermal stage of the rock evolution.

LIBS, elemental mapping, geology

15.12.2022