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Geochemical Analysis of Ironstone Preserved Molluscan Fossils of the Hell Creek Formation (Cretaceous) and Ludlow Member Of University of North Dakota UND Scholarly Commons Theses and Dissertations Theses, Dissertations, and Senior Projects 2008 Geochemical Analysis of Ironstone Preserved Molluscan Fossils of the Hell Creek Formation (Cretaceous) and Ludlow Member of the Fort Union Formation (Paleogene) of Southwestern North Dakota Tanya P. Justham University of North Dakota Follow this and additional works at: https://commons.und.edu/theses Part of the Geology Commons Recommended Citation Justham, Tanya P., "Geochemical Analysis of Ironstone Preserved Molluscan Fossils of the Hell Creek Formation (Cretaceous) and Ludlow Member of the Fort Union Formation (Paleogene) of Southwestern North Dakota" (2008). Theses and Dissertations. 154. https://commons.und.edu/theses/154 This Thesis is brought to you for free and open access by the Theses, Dissertations, and Senior Projects at UND Scholarly Commons. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of UND Scholarly Commons. For more information, please contact [email protected]. GEOCHEMICAL ANALYSIS OF IRONSTONE PRESERVED MOLLUSCAN FOSSILS OF THE HELL CREEK FORMATION (CRETACEOUS) AND LUDLOW MEMBER OF THE FORT UNION FORMATION (PALEOGENE) OF SOUTHWESTERN NORTH DAKOTA by Tanya P. Justham Bachelor of Science, St. Lawrence University, 2001 A Thesis Submitted to the Graduate Faculty of the University of North Dakota in partial fulfillment of the requirements for the degree of Master of Science Grand Forks, North Dakota May 2008 This thesis, submitted by Tanya P. Justham in partial fulfillment of the requirements for the Degree of Master of Science from the University of North Dakota, has been read by the Faculty Advisory Committee under whom the work has been done and is hereby approved. __________________________ Chairperson __________________________ __________________________ This thesis meets the standards for appearance, conforms to the style and format requirements of the Graduate School of the University of North Dakota, and is hereby approved. ____________________________ Dean of the Graduate School ____________________________ Date ii PERMISSION Title Geochemical Analysis of Ironstone Preserved Molluscan Fossils of the Hell Creek Formation (Cretaceous) and Ludlow Member of the Fort Union Formation (Paleogene) of Southwestern North Dakota Department Geology Degree Master of Science In presenting this thesis in partial fulfillment of the requirements for a graduate degree from the University of North Dakota, I agree that the library of this University shall make it freely available for inspection. I further agree that permission for extensive copying for scholarly purposes may be granted by the professor who supervised my thesis work or, in his absence, by the chairperson of the department or the dean of the Graduate School. It is understood that any copying or publication or other use of this thesis or part thereof for financial gain shall not be allowed without my written permission. It is also understood that due recognition shall be given to me and to the University of North Dakota in any scholarly use which may be made of any material in my thesis. Signature _______________________ Date _______________________ iii TABLE OF CONTENTS LIST OF FIGURES...........................................................................................................vii LIST OF TABLES..............................................................................................................ix ACKNOWLEDGMENTS...................................................................................................x ABSTRACT......................................................................................................................xii CHAPTER I. INTRODUCTION.......................................................................................1 Purpose.............................................................................................1 Location...........................................................................................2 Stratigraphic Nomenclature.............................................................3 Sedimentology and Paleogeography................................................5 Cretaceous/Paleogene Boundary in the Study Area........................5 Previous Work.................................................................................6 North Dakota Hell Creek and Ludlow Ironstone Fossils and Nodules.........................................................................6 Siderite Nodules and Fossils................................................7 II. METHODS................................................................................................11 Field Methods................................................................................11 Locality L6799...................................................................12 Locality L6521...................................................................12 iv Locality L6466...................................................................14 Locality L6808...................................................................16 Locality L6809...................................................................17 Lab Methods..................................................................................19 X-ray Diffraction...............................................................19 Isotopes..............................................................................21 Scanning Electron Microscopy..........................................22 Geochemist’s Workbench® Essentials...............................22 III. RESULTS..................................................................................................24 X-ray Diffraction...........................................................................24 *13C and *18O Isotope Results............................................................28 Scanning Electron Microscopy EDS Results.................................29 IV. DISCUSSION............................................................................................32 Composition...................................................................................32 Fossil Preservation.........................................................................33 Groundwater Geochemistry...........................................................38 Porewater Composition..................................................................46 Organic Influences.........................................................................47 Time Occurrence............................................................................48 V. CONCLUSIONS........................................................................................50 Future Work...................................................................................51 v APPENDICES...................................................................................................................53 A. X-ray Diffractometer Graphs.....................................................................54 B. Scanning Electron Microscopy EDS Results and Photographs.................70 C. Geochemist’s Workbench® Rxn Calculations for Siderite Replacement of Aragonite............................................................................................104 D. Geochemist’s Workbench® Act2 Eh-pH iron species stability diagrams..... .................................................................................................................117 REFERENCES................................................................................................................148 vi LIST OF FIGURES Figure Page 1. Study area location and bedrock geology map........................................................3 2. North Dakota stratigraphic column showing generalized stratigraphic nomenclature and relationships in the North Dakota portion of the Williston Basin........................................................................................................................4 3. Northwest view of Locality L6799 at Mud Buttes, Bowman County...................13 4. View east of Locality L6521, with relationship to K-Pg boundary.......................13 5. Specimen S4712, Sphaerium sp. (Locality L6521)...............................................14 6. View east, outline encompasses Larkin Locality L6466 in Bowman County.......15 7. Specimen S4704, Proparreysia percorrugata (Larkin Locality L6466)...............16 8. Ironstone nodule and associated unionoid fossil specimen S4727 (Larkin Locality L6466).....................................................................................................16 9. North view of Locality L6808, Das Goods area, Slope County............................17 10. South view of Locality L6809 at Mud Buttes, Bowman County..........................18 11. Specimen S4725, Campeloma sp. in nodule (Locality L6809).............................23 12. Nodule cores..........................................................................................................26 13. Specimen S2906, Proparreysia verrucosiformis (Locality L5233b)....................28 14. Silica replaced, distorted gastropod specimen S4726 (Locality L6809)...............30 15. Eh-pH stability diagrams for calcium and iron minerals and dissolved species...37 16. Initial diagram for the 10oC series of simulations................................................41 vii 17. Eh-pH diagram created for iron species
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