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Title: Computerized Qualitative and Quantitative Clay Mineralogy: Introduction and Application to Known Geological Cases.
Other Titles: Computerondersteunde kwalitatieve en kwantitatieve kleimineralogie: invoering en toepassing op bekende geologische vraagstukken.
Authors: Zeelmaekers, Edwin
Issue Date: 29-Apr-2011
Abstract: Clay minerals are some of the most abundant minerals in sedimentary rocks and have a unique set of properties, such as a large surface area and the capability to exchange water and cations with their environment from these surfaces. In addition clay minerals serve as raw materials for a wide variety of products and can indicate specific formation or diagenetic conditions. Despite their abundance and importance, clay minerals have historically been characterized with a low qualitative resolution and using only semi-quantitative methods because their small crystal size and highly variable composition make them very difficult to study in detail. Fundamental analysis problems were present from preparation through identification to quantification, both in the bulk rock as in the extracted clay fraction. It was recognized that a set of both existing and fundamentally new techniques existed which permits to overcome these problems and provide a highly accurate and reproducible qualitative and quantitative characterization of the clay mineralogy and the bulk rock mineralogy in general. The introduction of these techniques - which are mainly based on X-ray Diffraction (XRD) - in the Laboratory for Applied Geology & Mineralogy was a first major goal of this work. A bulk rock analysis technique was introduced that relies on homogeneous grinding and side-loading of random powders to overcome preparation issues. Data analysis is done using the QUANTA software which is a combination of whole pattern fitting of diffraction patterns of pure mineral standards and single peak quantification through the addition of a zincite internal standard. A critical element is the quantification of clay minerals off their 060-reflections instead of their highly variable 00l-reflections. Tests on artificial samples have shown the obtained results to be highly accurate. They are also in close agreement with bulk rock chemistry. Secondly also a detailed clay analysis technique was introduced. It relies on extracting the clays after first removing the cementing agents by a thorough pretreatment of the samples. This permits to produce high quality diffraction patterns of oriented glass slide preparations. These diffraction patterns can then be subjected to detailed qualitative and quantitative modeling using the SYBILLA software. It was demonstrated that the modeling results can be independently validated by chemical and Cation Exchange Cation (CEC) analyses. A second goal of this work was to demonstrate the value of the newly introduced techniques on a number of geological cases for which the traditional analysis methods could not deliver sufficient resolution. In a first study the provenance of muds and suspensions on the Belgian Continental Shelf was studied. After a detailed characterization of the muds themselves and sediments from the potential source areas it was concluded that the muds likely have a local origin, in specific the reworking of older clay-rich sediments, probably supplied by the Paleo-Scheldt river. A second study focused on a well known clay mineralogical transition near the Eocene-Oligocene boundary in the Southern North Sea Basin which is characterized by a relatively rapid decrease in smectite content. Convincing evidence was found linking the occurrence of the large quantities of smectite in the Eocene deposits to a volcanogenic origin. The transition itself was found to be less rapid than previously assumed and was reinterpreted as having a tectonic rather than climatological origin. In a third study earlier work (limited in resolution) was confirmed, demonstrating a Milankovitch controlled cyclicity of kaolinite in the Boom Clay. In addition to these three geological cases, also the mineralogy of the Boom Clay was characterized in detail.
Table of Contents: Table of Contents

INTRODUCTION
1. Introduction and Thesis Concept………………………………………………….1
2. Essentials of Clay Mineralogy & X-ray Diffraction………..……………………..3
3. Methodology: Past versus Present……………………………………………….15

PART 1: METHODOLOGY
4. Sampling & Initial Preparations………………………………………………….45
5. Sample & Standards Preparation for Quantitative Bulk Rock Analysis…………51
6. Extracting & Preparing the Clay Size Fractions…………………………………59
7. Additional Analyses……………………………………………………………...71
8. The X-ray Diffractometer………………………………………………………..87
9. Data & Lab Management………………………………………………………...91
10. Display & Preparation of XRD Patterns…………………………………………95
11. Quantitative Bulk Rock Analysis………………………………………………...99
12. Quantitative Bulk Rock Analysis & Chemistry………………………………...115
13. Detailed Clay Analysis…………………………………………………………123
14. Data Integration………………………………………………………………...159

PART 2: APPLICATION ON GEOLOGICAL CASES
15. The Provenance of the Muds on the Belgian Continental Shelf………………..165
16. Clay Mineralogy of the Eocene-Oligocene Interval of the Southern North Sea Basin........…………………………………………………273
17. Mineralogical Variations in Rupelian Milankovitch Cycles in the Boom Clay..311

CONCLUSION
18. Summary & Conclusions……………………………………………………….325


APPENDIX 1. The Boom Clay Project…………………………………………………..331
APPENDIX 2. The Provenance of the Muds on the Belgian Continental Shelf…………337
APPENDIX 3. The Clay Mineralogy of the Eocene-Oligocene Interval………………...368
APPENDIX 4. Mineralogical Variations in Rupelian Milankovitch Cycles…………….379


REFERENCES & PUBLICATION LIST…………..………..……………………………………381
ISBN: 978-90-8649-414-9
Publication status: published
KU Leuven publication type: TH
Appears in Collections:Division of Geology

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