FACULTEIT WETENSCHAPPEN Opleiding Master of Science in de geologie Quantitative mineralogy of a saprolite-soil sequence on a talc and chlorite bearing substrate, Upper Katanga, D.R. Congo. Els Timmermans Academiejaar 2014–2015 Scriptie voorgelegd tot het behalen van de graad Van Master of Science in de geologie Promotor: Prof. Dr. J. De Grave, Prof. Dr. E. Van Ranst Begeleider: Drs. M. Dumon Leescommissie: Prof. Dr. G. Baert, Prof. Dr. S. Bertrand ACKNOWLEDGEMENTS For any geology student, the graduating year is an exciting chapter in life. The master thesis is an important part of it. Luckily I could count on great support of my thesis promotor Prof. Dr. Eric Van Ranst. I would like to thank him for giving me the opportunity to do my master thesis in particular and studying in general at the Laboratory of Soil Science of the Geology and Soil Science Department. Without his knowledge, perseverance and dedicated time I would have a much tougher time in completing this document. I would like to express my sincere gratitude to my tutor Drs. Mathijs Dumon for answering my questions and for the help and guidance through the practical part of this master thesis. Veerle Vandenhende guided me in the Laboratory of Soil Science of the Geology and Soil Science Department. She explained and gave me insight into the lab analyses. It was a great pleasure to work with her. Furthermore, I would like to thank all people of the Soil Science Research Unit of the Ghent University for the company and the help. Last but not least, my parents and family may not be forgotten. They provided the support I needed to devote so much of my time in my education in general and this document in particular. They cared my every need and bore the considerable financial strain students impose upon parents all for their happiness and fruitful ending of their education. Els Timmermans i TABLE OF CONTENTS ACKNOWLEDGEMENTS ..................................................................................................................... i LIST OF FIGURES .............................................................................................................................. iv LIST OF TABLES ................................................................................................................................ vi SAMENVATTING ............................................................................................................................ viii 1. INTRODUCTION ............................................................................................................................ 1 1.1 Background and research significance ............................................................................. 1 1.2 Objectives ......................................................................................................................... 2 2. LITERATURE REVIEW ..................................................................................................................... 3 2.1 Geology ............................................................................................................................. 3 2.2 Weathering and formation of clay minerals .................................................................... 8 2.2.1 Weathering of talc .................................................................................................... 8 2.2.2 Weathering of chlorite ........................................................................................... 10 2.2.3 Formation of kaolinite ............................................................................................ 12 3. MATERIAL AND METHODS ......................................................................................................... 15 3.1 Environmental setting .................................................................................................... 15 3.2 Sampling strategy ........................................................................................................... 16 3.3 Physico-chemical analyses.............................................................................................. 16 3.3.1 Texture, clay separation and saturation ................................................................. 16 3.3.2 Soil acidity ............................................................................................................... 17 3.3.3 Cation exchange capacity and exchangeable base cations .................................... 17 3.3.4 Selective chemical extraction ................................................................................. 17 3.3.5 Total elemental analysis ......................................................................................... 18 3.4 Quantitative X-ray diffraction (QXRD) ............................................................................ 18 3.4.1 Random powder samples ....................................................................................... 21 3.4.2 Oriented samples ................................................................................................... 22 3.4.3 SiroQuant ................................................................................................................ 23 3.4.4 Python X-ray Diffraction (PyXRD) ........................................................................... 24 3.4.5 Calculation of the mineral composition ................................................................. 26 3.5 High resolution transmission electron microscope (HR-TEM) ....................................... 26 3.6 Micro X-ray fluorescence (XRF) .................................................................................... 26 3.7 Micromorphological analysis .......................................................................................... 27 ii 4. RESULTS ...................................................................................................................................... 28 4.1 Morphological properties ............................................................................................... 28 4.2 Physico-chemical properties .......................................................................................... 28 4.3 Total elemental composition .......................................................................................... 32 4.4 Weathering indices and molar ratios ............................................................................. 34 4.5 Total elemental composition of the silicate fraction ..................................................... 36 4.6 Trace elements ............................................................................................................... 38 4.7 Quantitative X-ray diffraction (QXRD) ............................................................................ 39 4.8 High resolution transmission electron microscope (HR-TEM) ....................................... 47 4.9 Micro X-ray fluorescence (µXRF) .................................................................................... 48 4.10 Micromorphological properties ..................................................................................... 53 5. DISCUSSION ................................................................................................................................ 59 5.1 Evolution of the physico-chemical and mineralogical properties of the two selected intervals .......................................................................................................................... 59 5.1.1 Interval 1 ................................................................................................................. 59 5.1.2 Interval 2 ................................................................................................................. 61 5.1.3 Weathering degree ................................................................................................. 63 5.2 Weathering of talc .......................................................................................................... 64 5.3 Weathering of chlorite ................................................................................................... 65 5.4 Formation of kaolinite .................................................................................................... 66 5.5 Relief inversion hypothesis ............................................................................................. 67 6. CONCLUSION .............................................................................................................................. 71 6.1 FUTURE RESEARCH ......................................................................................................... 72 7. REFERENCES................................................................................................................................ 73 8. APPENDIX 1 ................................................................................................................................. 87 9. APPENDIX 2 ................................................................................................................................. 89 10. APPENDIX 3 ............................................................................................................................... 91 11. APPENDIX 4 ............................................................................................................................... 93 12. APPENDIX 5 ..............................................................................................................................