Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1997 Stratigraphy and sedimentology of the Hadar Formation Afar, Ethiopia Tesfaye Yemane Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Geochemistry Commons, and the Geology Commons Recommended Citation Yemane, Tesfaye, "Stratigraphy and sedimentology of the Hadar Formation Afar, Ethiopia " (1997). Retrospective Theses and Dissertations. 11577. https://lib.dr.iastate.edu/rtd/11577 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. 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Photographs included in the original manuscript have been reproduced xerographically in this copy. Kgher quality 6" x 9" black and white photographic prints are available for any photographs or illustrations appearing in this copy for an additional charge. Contact UMI directly to order. UMI A Bell & Howell Infonnadon CompaiQ^ 300 North Zed) Road, Ann Aibor MI 48106-1346 USA 313/761-4700 800/521-0600 \ I ) Stratigraphy and sedimentology of the Hadar Formation Afar, Ethiopia by Tesfaye Yemane A dissertation submitted to the graduate faculty in partial flilfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Major: Geology Major Professor; Dr. Carl F. Vondra Iowa State University Ames, Iowa 1997 DMI Nuinber: 9814714 UMI Microform 9814714 Copyright 1998, by UMI Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. UMI 300 North Zeeb Road Ann Arbor, MI 48103 u Graduate Collage Iowa State University This is to certify that the Doctoral dissertation of Tesfaye Yemane has met the dissertation requirements of the Iowa State University Signature was redacted for privacy. Signature was redacted for privacy. For the Maj Signature was redacted for privacy. For the Graduate Collage iii TABLE OF CONTENTS page LIST FIGURES ^ LIST OF TABLES x INTRODUCTION I Method of study 2 Previous work 4 Volcano-tectonic setting 6 STRATIGRAPHYOF THE HADAR FORMATION 9 Basal Member 9 Sidi Hakoma Member 12 Denen Dora Member 13 Kada Hadar Member 14 Lower Kada Hadar Member 15 Upper Kada Hadar Member 17 PETROLOGY 19 Conglomerate 20 Texture 20 Composition 29 Sandstone 34 Texture 34 Composition 40 Heavy mineral analysis of sandstones 49 Mineralogy of heavy minerals 51 Heavy mineral associations 55 Distribution of heavy mineral associations 59 Mudrock 61 Texture 61 Composition 64 X-ray diffraction 64 Differential thermal analysis 66 Chemical analysis 67 Carbonates 71 Tuffs and bentonitic tuffs 72 Provenance 75 iv FACIES AND ENVIRONMENT OF DEPOSITION 82 Lithofacies codes 83 Massive clast-supported conglomerate and trough cross-bedded sandstone facies association - Facies A 83 Description 83 Depositional environment 94 Trough cross-bedded sandstone, siltstone, and mudstone facies association - Facies B 96 Description 96 Depositional environment 107 Interbedded ostracod-bearing fissile shale, thinly bedded gastropod limestone, fine-grained sandstone and mudstone facies association - Facies C 111 Description 111 Depositional environment 117 Interbedded fine grained sandstone, siltstone and mudstone facies association - Facies D 120 Description 120 Depositional environment 122 THE RELATIONSHIP OF HOMINID REMAINS AND LITHOFACIES 125 Sidi Hakoma Member 126 Denen Dora Member 128 The First "Family" site (A1 333) 128 Lower Kada Hadar Member 131 "Lucy" site (AL 288) 132 Upper Kada Hadar Member 133 Homo species (AL 666) 133 PALEOGEOGRAPHY AND ENVIRONMENTS 13 5 SUMMARY 143 APPENDIX A HADAR CONGLOMERATES RECALCULATED CLAST POINT COUNT 148 APPENDIX B RECALCULATED ROCK FRAGMENTS POINT COUNT 149 APPENDIX C STATISTICAL GRAIN SIZE DISTRIBUTION PARAMETERS OF SANDSTONE 151 APPENDIX D SANDSTONE COMPOSITION AND MINERALOGY 153 APPENDIX E HEAVY MINERAL PERCENTAGE IN GRAIN SIZE BETWEEN 500-250^ 250-125^, AND 125-63^ 155 APPENDIX F HEAVY MINERAL COMPOSITION OF THE SANDSTONES 157 APPENDIX G DISTRIBUTION OF HEAVY MINERALS ASSOCIATION AND THEIR STRATIGRAPHIC POSITIONS 159 APPENDIX H PERCENTAGE OF CLAY, SILT AND SANDOF MUDROCKS 161 APPENDIX I PALEOCURRENT MEASUREMENTS OF TROUGH CROSS-BEDDED SANDSTONES TAKEN FROM THE DIRECTION OF SEDIMENT TRANSPORT 162 APPENDIX J. GPS LOCATION OF GRAPGIC SECTIONS OF THE HADAR FORMATION 164 REFERENCES 165 ACKNOWLEDGMENTS 181 VI LIST OF nCURES Page Figure 1. Map of Ethiopia and location of the study area 3 Figure 2. Outline map of the East African Rift System and related structural elements 7 Figure 3. Graphic sections of the Hadar Formation 10 Figure 4. Generalized stratigraphic section of the Hadar Formation 12 Figure 5. DD-3 conglomerate of Denen Dora Member showing a disorganized, coarse, open clast-supported texture 22 Figure 7. a) DD-3 conglomerate of the Denen Dora Member showing a sequence of fine filled fi-amework at its lower portion, and grading upward into disorganized, coarse open framework, b) KH-3 conglomerate of the lower part of the Kada Hadar Member showing a tightly packed framework in the lower portion and grading vertically into a disorganized, coarse, open framework and a poorly organized coarse, open framework 24 Figure 6. KH-3 and KH-8 conglomerates of the Kada Hadar Member showing a disorganized, coarse, open matrix-supported texture 26 Figure 8. Probability plots of DD-3, KH-3, and KH-8 conglomerates interpreted as braided stream deposits 30 Figure 9. The lithology of the matrix-supported conglomerate 30 Figure 10. Ternary plot showing the relative abundance of mafic (Cvb), felsic (Cvr) and pyroclastic (Cvp) rocks 33 Figure 11. Probability plot of the sandstones of the Sidi Hakoma and Denen Dora members 35 Figure 12. Probability plots of the sandstones of the Kada Hadar Member 36 Figure 13. Representative grain size distribution of the DD-3 sandstone of the Denen Dora Member showing a variation in grain size from west to east 37 Figure 14. Scatter diagram of mean size versus skewness, kurtosis and standard deviation 38 vii Compositional classification of sandstone 42 Relative abundance of quartz, feldspar and rock fi"agments in the sandstone 46 Ternary plots showing the relative abundance of basic (Rb) and acidic (Rr) and undifferentiated volcanic Segments (Rt) 48 Heavy mineral percentage in size fi-action between 500 - 63 [i, 250-125|i, and 125-63|i 50 X-ray diflfraction tracing of heavy minerals in sandstone 52 Photographs of heavy minerals of the sandstone 53 Heavy mineral percentages for the sandstones of the Hadar Formation 56 Ternary plots showing the heavy mineral associations in the sandstones of the Hadar Formation 60 Classification of mudrocks Hadar Formation 63 Clay content of the mudrocks of the Hadar Fonnation 63 X-ray diffraction pattern of mudrocks 65 X-ray diffraction pattern of mudrocks 65 DTA, TG and derivative TG curves of mudrock 68 X-ray diffraction pattern of carbonate 73 X-ray diffraction tracing of tuffs 75 Provenance of the Hadar Fonnation 78 Graphic section of the Denen Dora Member at Kahuli Koma 87 Graphic section of Kada Hadar Member 32 Representative diameters of rhizoliths common in the siltstones of the upper part of the Kada Hadar Member 91 Photographs of the massive to crudely-stratified and cross-bedded clast - supported conglomerate and trough cross-bedded sandstone facies association - Facies association A 92 Block diagram showing an alluvial fan complex along the Ethiopian Escarpment and braided streams prograding into a shallow rift lake 95 Graphic section of Basal Member at Kenia Koma 99 Paleocurrent rose diagrams for sandstones of the Hadar Formation 100 Graphic section of Sidi Hakoma Member 101 Photographs of the large scale trough cross-bedded sandstone, siltstone and mudstone - Facies association B 122 Block diagram of braided tributaries joining the axial meandering stream prograding north and into a deltaic depositional environment 108 Lithofacies of the lower sequence of the interbedded ostracod-bearing fissile shale, thinly bedded gastropod limestone, fine grained sandstone and mudstone facies association - facies association - Facies association C 112 Lithofacies of the upper sequence of the interbedded ostracod-bearing fissile shale, thinly