Title:  X Ray analysis: work strategy and applications (Análisis de imágenes de Rayos X: estrategia de trabajo y aplicaciones).

Lecturer: Prof. Antonio García Casco. Dept. de Mineralogía y Petrología - Instituto Andaluz de Ciencias de la Tierra, Facultad de Ciencias (Universidad de Granada, Spain).

Date: Tuesday April the 22nd 2014, 12.00h.

Place: room 4

Abstract: In this talk I shall highlight the merits of X-ray mapping for deciphering the nature of geological (and other) materials and processes. X-ray maps are two dimensional images that describe the distribution (concentration) of elements in an area. They are obtained with electron microscopes on polished areas of samples, which are scanned (beam or stage scanning) for a number of element signals (EDS or WDS) at a time, normally concentrated in major and minor amounts, but trace elements can be also scanned under special machine settings. The raw data can be transformed into quantitative (e.g., wt% element, wt% oxide, atoms per formula unit,…) using internal standards and calibration procedures. The processing of a set of images resembles multispectral analysis of an area, and includes image (matrix) manipulation by means of any mathematical operation/function and treatment for mineral identification, mineral abundance, textural-chemical analysis, mineral composition variation (mineral zonation), element distribution along profiles, binary, ternary or quaternary plotting, etc. Since the images are positioned in absolute X-Y space (stage scanning), they are also useful for planning the analytical strategy of particular points/areas of the objects with the microprobe or other instruments (e.g., LA-ICP-MS). Collecting X-ray maps of an area is time-consuming (several hours or tens of hours), but 2D element maps are invaluable for showing details of phase composition in textural/structural/fabric context which are normally non-appreciated in qualitative optical, BSE, or secondary electron images. The information contained in a full set of X-ray element images of an area is vast and can be extracted after appropriate processing. Hence, this technique has become a necessary tool for providing quantitative information for deciphering phase assemblage (i.e., rock) evolution in space and time.

More info: http://www.ugr.es/~agcasco/personal/ >> Imágenes de RX

Biografical summary:

Antonio García Casco, Ph.D. 1993 (University of Granada), is full Professor of Petrology and Geochemistry at the University of Granada. His main research interest are metamorphic geology, phase equilibria, P-T-t paths and experimental petrology, with applications to the geodynamic evolution of plate margins (mostly in the Betics, Variscian and Caribbean belts). He has led several research projects in the Caribbean region. More information available at http://www.ugr.es/~agcasco/personal.