Qualitative and Quantitative Analysis of Clays and Clay Minerals: Application in Geological Studies

January 28th to 31st 2020

Dr. Siliva Omodeo-Salé, UNIGE

Mme Emmanuelle Ricchi, UNIGE

M. Davide Carraro, UNIGE

Prof. Branimir Segvic, Texas Tech University, US

Aims of the course Clay minerals are encountered in a variety of geological materials and, as such, represent an important line of research. Due to the environment in which they appear, that is constantly crisscrossed by man's activity, clays are studied from different aspects of human endeavor. This short course aims to familiarize attendants with basic concepts of crystal-chemical characterization of clay mineral structures (Day 1), identification of clay minerals using the most common analytical techniques (Day 2), and finally, provide an insight into utilitarian values of clay science principally in the understanding of the evolution of sedimentary basins, paleoclimate reconstructions, and hydrocarbon exploration (Day 3). The attendants of this course will acquire the ability to independently prepare and interpret dataset from clay analysis. These abilities could be used for their own research, thanks to the in-house clay analyses laboratory (centrifuge, X-ray diffractometer, spectral analysis software).

Detailed program

Day 1: Importance of clay minerals; Review of mineralogy fundamentals; Crystal chemistry review;; Crystal structures of clay minerals – Chemistry – Species – Nucleation and crystal growth; Surface properties of clay minerals (water saturation, cation exchange capacity, layer charge, specific surface, rheological and mechanical properties); Clay microtextures; Clay mineral systematics and speciation.

Day 2: Principles of X-ray powder diffraction; Separation and preparation of clays for XRD analysis; XRD identification of clay phases – Malvern Panalytical's HighScore Software; Mixed-layer clays and their identification; Modeling of clay mineral diffraction spectra Sybilla Software; Introduction to quantitative phase analysis; basics Rietveld analyses (Malvern Panalytical's HighScore); Principles of Scanning electron microscopy and clay analysis.

Day 3: Clays in sedimentary environments – detrital vs. neogenetic clays; Diagenesis and clay mineral transformations in sedimentary series (this will also include the susceptibility of diagenetic patterns to system geochemistry; case study 1); Concepts of chlorite (Árkai) and illite (Kübler) "crystallinity" indices in diagenesis and low-grade metamorphism (basin thermal maturation) (case study 2); Clays and petroleum geology – clay-organic relations, temperature and maturations, migration, overpressuring, sandstone cementation; Clay minerals and their paleoenvironmental interpretation (case study 3).

Day 4: Case study 1: Diagenesis of Fe-rich Gabon basin sediments – study conducted at UniGE couple of years ago; we continued at TTU; Case study 2: Late Paleozoic shales from the Anadarko and Permian basins of the United States (Work of my PhD students); Case study 3: Reconstruction of the Quaternary paleoclimate across the Southern High Plains (Texas and New Mexico) using clay mineral data (Work of my BS and MS students); Open discussion on specific attendants case studies

University of Geneva

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