Publication : Spectrochimica Acta Part B: Atomic Spectroscopy

Publication du papier sur l’utilisation de la LIBS afin de déterminer les roches volcanique en Islande.

In situ Laser Induced Breakdown Spectroscopy as a tool to discriminate volcanic rocks and magmatic series, Iceland

roux et al 2015

Highlights

•Portable LIBS applied to field geology
•Fast semi-quantitative geochemical analysis of volcanic rocks and magmatic series
•Discriminant analysis and statistical treatments for LIBS compositional data

Abstract

This study evaluates the potentialities of a lab-made pLIBS (portable Laser-Induced Breakdown Spectroscopy) to sort volcanic rocks belonging to various magmatic series. An in-situ chemical analysis of 19 atomic lines, including Al, Ba, Ca, Cr, Cu, Fe, Mg, Mn, Na, Si, Sr and Ti, from 21 sampled rocks was performed during a field exploration in Iceland. Iceland was chosen both for the various typologies of volcanic rocks and the rugged conditions in the field in order to test the sturdiness of the pLIPS. Elemental compositions were also measured using laboratory ICP-AES measurements on the same samples. Based on these latter results, which can be used to identify three different groups of volcanic rocks, a classification model was built in order to sort pLIBS data and to categorize unknown samples. Using a reliable statistical scheme applied to LIBS compositional data, the classification capability of the pLIBS system is clearly demonstrated (90–100% success rate). Although this prototype does not provide quantitative measurements, its use should be of particular interest for future geological field investigations.

Publicités

Publication

Cover imageNotre  premier papier sur les applications de la LIBS en géologie est en ligne dans la revue Spectrochimica Acta Part B: Atomic Spectroscopy

Testing a portable Laser-induced Breakdown Spectroscopy system on geological samples

Jozef Rakovskýab , Olivier Musseta, JeanFrançois Buoncristianic, Vincent Bichetd, Fabrice Monnae, Pascal Neigec, Pavel Veisbf`

  • a Laboratoire interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS – Université de Bourgogne, 9 Av. A. Savary, BP 47 870, F −21078 DIJON Cedex, France
  • b Department of Experimental Physics FMFI, Comenius University, Mlynská dolina, 842 48 Bratislava, Slovakia
  • c Laboratoire Biogéosciences, UMR CNRS 6282 – Université de Bourgogne, 6 Boulevard Gabriel 21000 Dijon, France
  • d Laboratoire Chrono-Environnement, UMR CNRS 6249 – Université de Besançon, 16 Route de Gray 25000 Besançon, France
  • e Laboratoire ARTéHIS, UMR CNRS 6298 – Université de Bourgogne, 6 Boulevard Gabriel 21000 Dijon, France
  • f State Geological Institute of Dionýz Štúr, Mlynská dolina 1, 817 04 Bratislava 11, Slovakia
     

    Abstract

This paper illustrates the potentialities of a home-made portable LIBS (Laser-Induced Breakdown Spectroscopy) instrument in Earth sciences, more particularly in geochemically recognizing (i) tephra layers in lacustrine sediments and (ii) fossilization processes in ammonites. Abundances for selected lines of Al, Ca, Fe, Ti, Ba and Na were determined in lacustrine chalk sediments of the Jura, where the Laacher See Tephra (LST) layer is recorded. A statistical treatment of elemental maps produced from the section of a sedimentary column containing the LST event allows instrumental conditions to be optimized. Accumulating spectra from close shot positions gives better results than multiplying shots at the same location. A depth profile method was applied to study ammonite fossilization (pyritization, phosphatization) processes. Depth variations of Fe, Ca, Al intensities, and Fe/Ca and Al/Ca ratios provide indications about pyritization, but phosphatization processes cannot be determined with our device.