The mineral liberation analysis setup (MLA) consists of a scanning electron microscope (SEM) - based backscattered electron (BSE) image with an energy dispersive X-ray system (EDX) for elemental analysis and a computer software that integrates images and X-ray identification of minerals and maps their distribution. Thereby, various quantitative and qualitative data sets are collected including grain size distribution and shape parameters such as aspect ratio, shape factor and angularity. Other techniques, e.g. the Gazzi-Dickinson point counting method or frequently questionable image analysis software to extract data for textural analysis are time consuming, strenuous and with limitations that need to be addressed. Significant productivity of the mineral liberation analysis provides statistical representation and thereby stringent arguments to detect and suggest some potential solving in uncertainty and complexity of the submarine gravity flows phenomenon that is extremely difficult to monitor, however volumetrically the most significant processes moving sediments on Earth. The mineral liberation analysis seems to be one of the most suitable method to acquire such data set.
20 December 2022 in Gospodarka Surowcami Mineralnymi - Mineral Resources Management
SEM Automated Mineralogy (SEM-AM) is an analytical system based on a scanning electron microscope (SEM) with backscattered electron detector and an energy dispersive X-ray spectrometer (EDS). This automated tool enables to quantify mineralogy, size and geometry of solid matter components. The paper presents a SEM-AM application in detection of mineralogical and textural sediment sorting on the example of a submarine gravity flow record from the Cergowa sandstones (Lower Oligocene) in the Polish Outer Carpathians. Analysis of high quality backscattered electron (BSE) imagery in combination with EDX spectra discriminates mineral phases in polished samples. These data are then processed by the mineral liberation analysis (MLA) software in order to extract size and shape information, and combine, compare and group components for further examination. Automated data extraction provides highly representative measurement statistics devoid of manual work bias. The Cergowa sandstones were prepared for the analysis as non-granular samples in coated thin sections and granular samples in epoxy mounts. The former samples provide mineralogical data whereas the latter additionally generate textural parameters, both essential in interpretation of variability of flow competence. Comparisons between samples from an individual bed and between different beds of the measured sections give insights into the spatial and temporal flow development at a given locality. On the other hand, a comparison of different sections and regions of the formation will provide basis for the reconstruction of submarine flow events throughout the sedimentary basin and contribute to the characterisation of the provenance areas. Highly detailed quantitative data generated by this procedure have great potential in helping to recognise complex relationships between mineralogical and textural sorting by depositional processes.
1 December 2014 in Gospodarka Surowcami Mineralnymi - Mineral Resources Management
The scanning electron microscope analysis of the Cergowa sandstones brings new data on their petrological features and chemical composition. Previous work in standard petrographic examination, e.g. polarising (PL) or cathodoluminescence (CL) microscopy, displayed limited information on grain surface topography and only assumptions to their geochemistry. Both identification and characterisation of minerals are fundamental in the progress of mining and minerals processing systems. Detrital grains of the Cergowa sandstones are bound by calcite and dolomitic cement and commonly corroded by diagenetic fluids, however, in varying degrees, which is illustrated here by feldspar, quartz and dolomite minerals. Dissolution processes of marginal parts of these mineral grains resulted in corrosion, which increased the contact surface between the grains and the cement. The difference in resistance to these processes was observed not only among distinct groups of minerals, but also within the group of feldspars: between K–feldspars and minerals of plagioclase. That combination resulted in exceptionally strong cementation of the Cergowa sandstones, which is expressed by their high hardness and resistance to abrasion, freezing, and thawing. Inherent parameters of sandstones are characterised by their petrographical properties.