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X-Ray Diffraction Study of Mineralogical Composition of Mudstones from Eastern Gadaref Area, Sudan

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X-Ray Diffraction Study of Mineralogical Composition of Mudstones from Eastern Gadaref Area, Sudan SD9800025 X-RAY DIFFRACTION STUDY OF MINERALOGICAL COMPOSITION OF MUDSTONES FROM EASTERN GADAREF AREA, SUDAN YASS1N AHMED A. KA8JMEL01K A THESIS SUBMITTED FOR THE PARTIAL FULFILEMENT OF THE DEGREE OF MASTER OF SCTENCE INFHYSICS PHYSICS DEPARTMENT FACULTY OF SCIENCE UNIVERSITY OF KHARTOUM SEPTEMBER 1996 We regret that some of the pages in this report may not be up to the proper legibility standards, even though the best possible copy was used for scanning ABSTRACT X-RA Y DIFFRACTION STUDY OF M1NERAL0GICAL COMPOSITION OF MUDSTONES FROM EASTERN GADAREF AREA, SUDAN M.Sc. by YASSIN AHMED ABDELGADIR KARIM ELDIN 1996 This study reviews the theoretical and experimental aspects of Xray diffraction (XRD) technique. Moreover, the mineralogical composition of some mudstones from Gadaref region has been investigated using DIFFRAC-AT software package, by means of searching and matching procedure in the standard XRD patterns edited by the International Center for Diffraction Data (ICDD). The X-ray diffraction analysis of the Gadaref mudstones revealed that quartz, kablinite and tridymite are the major mineral constituents of these rocks. Whereas other minerals like alunite, coalingate, cristabolite, gutsvechite, hematite, meta-alungen, minamite, monteponite, samarskite , chlorie, illite and smectite represent minor constituents in some samples. Most of the mudstone samples investigated have kaolinite content between 71-100 % This most probably indicates that these rocks were subjected to intense weathering and leaching under warm humid climate. These conditions seem to be less favourable for the formation of clay minerals chlorite, illite and smectite. Generally, the clay mineral types, abundances and distribution appear to be influenced mainly by source rock geology, the local environment and climate. Moreover, the high silica content of the mudstones reflects the influence of both hydrothermal and weathering processes. The high kaolinite content of these mudstone might suggest a good potential for economic exploitation of the kaoline deposits. Further studies, however, might be needed to investigate other technical properties. Suggestions for further work by XRD are given, and include further additions to the refinement procedures and the purchasing of new computer's facilities. (i) VsJ' M-Jai .ij^J' l^N1 J_^ ^yUill JSLiJl LL^ jl^Ji ^y*-"—J (DIFFRAC-AT) . (ICDD) ijJ-\ ol;U Jjj J (tridymite) OJUJO^'J (kaolinite) c~»LJji53i (quartz), yjj—^J ,(alunite) C-JI Jjili J ^ OJI «ii j—» ,(gutsvechite) CJIL~V (cristabolite) , O-J^I^—j ^ ,(minamite) cu-L-u^ ,(meta-alungen) uy^yyil - iv ,(hematite) CJU A_«J ^y iLu* y,i\i. Jic (samarskite) C-JISL.JL.L- J <. (monteponite) C-J -v \ J_-J (kaolinite) C-JLJJL_T (^^-IP t^ci- oLu*)i «J_ft (Jijc 01 ^4 i^jj] o-vby«j' Lf»l ^^ J_JA-A)I eJL* J-b" 01 oJ_P J S 1>JL_-Jl o!_j_ji<' 0' .r- i jJJ; JS- v'di 4JJI>-I OLLAJI J Ju^swdl yl ,/«• Lc.j iJuJl(silica) J LA oi Ji js-io yJaJi jU^-Vi »iA iJuJi (kaolinite) C-JLJJ15^JI OL.^- OI IJL* (ii) Several individuals have helped in one way or another during the preparation of this study. If I decide to enumerate, the listing will definitely be lengthy. However, 1 must mention certain people whose help was certainly invaluable. | Firstly, my Supervisor, Dr O.man Mahmoud Abdullatif who takes i most of the gratitude for his constant Iv.'lp and guidance throughout the £ course of this project. I Secondly, I would like to record my deep appreciation, to Dr. \ Osman Dawi Eisa who is my former supervisor. \ Thirdly, I would like to express my gratitude to Dr. M.H.Shaddad I for the installation of DIFFRAC-AT from which I learned quite alot in ? relation to the software package, lam particulrly grateful to my colleagues | Mr.H.H.Idris who helped me also in the installation of DIFFERAC-AT. ? Fourthly, lam particulrly grateful to Computer Laboratory Group for I providing Laser Jet III printer which matches the DIFFRAC-AT package, * for making this study possible by giving me access to the Department's I resources. Also my great thanks are extended to Mr. Hosham, Miss. Mona H and Miss. Hyfa working for Gortas Computer Service for rearrangements I and decorations. I Fifthly, on behalf of the Physics Department, Faculty Of Science, I University Of Khartoum, I would like to pay tribute to the following | International Organizations: The International Atomic Energy Agency (IAEA) for donating the diffractometer and it's accessories, the International Program in Physical Sciences(IPPS) for their generaous gift, the DIFFRAC-AT software. At last but not least, members of my extended family have, of course, been extremely supportive and they all deserve a special word of my thanks. Of all, I would like to acknowledge the role of my parents (specially my mother) for encouraging me to take this endeavour. lam also deeply indepted to my brothers Moatasim, Mohammed for their generous financial assistance, without which this research would have been impossible to carry out. Also, my great thanks go to my uncle Dr. KarimEldin for his moral support and the peaceful atmosphere he provided to me. (iii) DEDICATION To my father and specially to the soul of my mother, Mariam (Mimi), whose sudden departure on 7 November 1996 has surely deprived me of the felicity of accomplishing this work with her and whom I will never forget for such a moment . iv) Page No. ABSTRACT i ACKNOWLEDGEMENTS iii DEDICATION iv CHAPTER 1 1 INTRODUCTION 1 1-0 Introduction 1 1-1 Objectives 2 1-2 Methods 2 CHAPTER II 4 THEORETICAL BACKGROUND 4 II-O Introduction 4 II-1 The Crystalline Solid 4 11-2 The Unit Cell 4 11-3 The Crystal Lattice 5 11-4 Crystallographic Notation "Miller Indices" 8 II-5 The Reciprocal Lattice 10 11-6 X-Ray Diffraction 11 11-7 Detennination of d-spacing and Intensities 14 H-8 The Intensity of Diffraction 15 II-8.a. Scattering by an Electrons 15 II-8.b. Scattering by an Atom 16 II-8.C. Scattering by a Unit Cell 19 II-8.d. The Temperature Factor 19 II-8.e. The Absorption Factor 21 CHAPTER HI 22 EXPERIMENTAL TECHNIQUE AND DATA PROCESSING 22 III-O Introduction 22 III-l Production of X-Rays 22 III-2 The X-Ray Generator 26 III-3 The Cooling System 26 III-4 The Goniometer 28 III-5 The Detector 28 III-6 TheDACO-MP 28 III-7 Mode of Operation of The Diffractometer 30 III-8 Data Processing with the DACO-MP 32 III-8 a. The Peak Search 32 III-8.b. The Extended Operations 33 II[-9 Data Processing with DIFFRAC-AT V3.1 34 111-10 Samples Separation and Preparation 36 III-11 Data Collection of Mineral Samples 36 Using D500 Measuring Routine CHAPTER IV 37 GEOLOGICAL LITERATURE REVIEW 37 IV-0 Introduction 37 IV-1 Mineralogical Compositions 37 IV-2 Clay Minerals 37 IV-3 Regional Geology 41 CHAPTER V 43 RESULTS, INTERPRETATION AND DISCUSSIONS 43 CHAPTER VI 70 CONCLUSIONS AND RECOMMENDATIONS 70 REFERENCES 71 CHAPTER INTRODUCE sj, 1-0 Introduction: X-ray diffraction (XRD) is the t efficient method for the ; detemiination of the mineralogi: alconv on rocks and especially fine grained minerals with complex structur ke -lay minerals, which occur mostly in sedimentary rocks such as sai ones, mudstones, claystones and limestones (Tucker, 1988, 1991). From a geological point of view the knowledge of mineralogy is highly important for rock classification and the determination of origin and depositional environments of rocks. Moreover, the mineralogy is helpfull in geological prospecting, exploration and evaluation of the economic potential : of mineral deposits. This depends primarily on accurate identification of the I minerals, knowledge of the composition and association in which they occur j. in nature. Therefore, it is important to study the characteristic of the deposits f qualitatively. ' Genetically, minerals are natural chemical compounds and are natural \ products of various physico-chemical processes going on in the earth crust, '. including the products of the life activity of various organisms. Clay minerals are the most abundant minerals on the surface of the | earth.This is illustrated by the fact that they are the essential constituents of | fine sedimentary rocks, such as mudstones, claystones, and shales making up jj to 75 % of the total sediments composition. They are hydrous a-lumino ; silicates with specific sheet or layered structures.Common clay minerals include kaolinite, illite, smectite and chlorite. Clay minerals are attributed to three origins: (i) inheritance, (ii) neoformation and (iii) transformation ', (Tucker, 1991). The samples investigated are collected from several outcrops from eastern Gadaref area. These samples are mainly mudstones and siltstones rocks belonging to what is known in Sudan as the "Nubian Sandstone Formation . The age of these rocks is of Cretaceous age and the depositional £>YWivonments of these rocks is of fluvial river origin (Omer, 1983). I (0 1-1 Objectives: The objectives of this work are, first, to review the theoretical and experimental aspects of XRD technique and, second, to characterize and determine the mirteralogical composition of some mudstones and to assess their potential in kaolin industry. 1-2 Methods: The nmdstone samples were prepared by crushing, disaggregation and sieving. Then, the XRD analyses were carried out on whole powdered samples. Methods and approaches followed in this study are shown in Fig.I-1. The format of this thesis will be as follows : The elementary theory of crystal lographic notatioh and XRD theory will be discussed in chapter II.In chapter III the experimental set up, data processing with DIFFRAC-AT software, samples preparation and collection are given .The geological literature review are given in chapter IV. Chapter V deals with the data analysis and the results obtained using DIFFRAC-AT routine facilities, and finally the conclusions and recommendations are given in chapter VI.
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