Tectonosedimentologic Significance of the Upper Cretaceous Frontier Formation, North-Central Wyoming Nazrul Islam Khandaker Iowa State University
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Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1991 Tectonosedimentologic significance of the Upper Cretaceous Frontier Formation, north-central Wyoming Nazrul Islam Khandaker Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Geology Commons Recommended Citation Khandaker, Nazrul Islam, "Tectonosedimentologic significance of the Upper Cretaceous Frontier Formation, north-central Wyoming " (1991). Retrospective Theses and Dissertations. 9536. https://lib.dr.iastate.edu/rtd/9536 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]. 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Tectonosedimentologic significance of the Upper Cretaceous Frontier Formation, North-central Wyoming by Nazrul Islam Khandaker A Dissertation Submitted to the Graduate Faculty in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY Department: Geological and Atmospheric Sciences Major; Geology Signature was redacted for privacy. In Charge/^of Major Work Signature was redacted for privacy. For the Major Department Signature was redacted for privacy. For the Graduate College Iowa State University Ames, Iowa 1991 I 11 TABLE OF CONTENTS ABSTRACT ' GENERAL INTRODUCTION 3 Study Area 3 Research Objectives 3 Study Methods 6 CHAPTER I. STRATIGRAPHY AND 9 SEDIMENTOLOGY OF THE UPPER CRETACEOUS FRONTIER FORMATION, NORTH-CENTRAL WYOMING ABSTRACT 10 INTRODUCTION 12 FACIES RELATIONSHIPS 17 Lower Frontier Unit: Bighorn Basin 17 Lower Frontier Unit; Powder River Basin 30 Middle Frontier Unit: Bighorn Basin 34 Middle Frontier Unit: Powder River Basin 37 Significance of the Polymictic Conglomerate 41 Upper Frontier Unit: Bighorn Basin 47 Upper Frontier Unit: Powder River Basin 49 ENVIRONMENT OF DEPOSITION 51 Overall Depositional Environment 51 ill Depositional Setting for the Lower 53 Frontier Unit Depositional Setting for the Middle 55 Frontier Unit Depositional Setting for the Upper 56 Frontier Unit FRONTIER TRACE FOSSILS AND PALEOBATHYMETRY 57 CONCLUSIONS 63 REFERENCES 65 CHAPTER II. TECTONIC SIGNIFICANCE OF 72 THE UPPER CRETACEOUS TORCHLIGHT SANDSTONE AND ITS EQUIVALENTS, NORTH-CENTRAL WYOMING ABSTRACT 73 INTRODUCTION 7 6 Objective 78 Analytical Techniques 80 CLAST FABRIC 83 CLASTS DATA AND CONSTRAINTS ON PROVENANCE 102 AND TECTONICS Chert Clasts 102 Andesite Clasts 110 Granite Clasts 127 Quartzite Clasts 139 SIGNIFICANCE OF THE ANDESITE-GRANITE CLASTS DATA 143 Control on Foreland Basin Sedimentation 144 iv CONCLUSIONS 140 REFERENCES 150 CHAPTER III. UPPER CRETACEOUS FRONTIER 157 BENTONITE GEOCHEMISTRY AND CONSTRAINTS ON PROVENANCE AND TECTONICS ABSTRACT 158 INTRODUCTION 160 GEOLOGY OF BENTONITES 161 Field Techniques 168 Laboratory Techniques 169 RESULTS 170 GEOCHEMICAL CONSTRAINTS ON TECTONIC SETTING 177 Detrital Mineralogy of Bentonites 179 Zircon Morphology and Magma Composition 182 Trace-Element Geochemistry of Shale 186 PROVENANCE AND TECTONIC IMPLICATIONS 191 CONCLUSIONS 195 REFERENCES 196 CHAPTER IV. PETROLOGY AND DIAGENESIS 201 OF THE UPPER CRETACEOUS FRONTIER SANDSTONES, NORTH-CENTRAL WYOMING ABSTRACT 202 V INTRODUCTION 204 Objective 204 SANDSTONE PETROLOGY 207 DETRITAL MODES 213 Implications of the Sandstone Composition 229 SANDSTONE DIAGENESIS 235 Chemical Constraints on Diagenesis and Provenance 239 CONCLUSIONS 243 REFERENCES 244 GENERAL CONCLUSIONS 248 ACKNOWLEDGEMENTS 251 vi LIST OF FIGURES Page CHAPTER I. Figure 1. Location map of study area 4 Figure 2. Outcrop map of the Upper Cretaceous 13 Frontier Formation in north-central Wyoming. Selected localities are also shown Figure 3. Photograph showing conformable 16 Mowry (Km) - Frontier (Kf) contact relationship at the Lovell locality. The person standing is for scale Figure 4. Photograph of basal part of dipping 18 lower Frontier unit near Greybull showing thin layers of sandstone interbedded with dark gray mudstone. The underlying unit is Mowry Shale Figure 5. Photograph of Diplocraterion 19 ichnofossil assemblage in Peay sandstone (lower Frontier unit) near Greybull. Length of the hammer is 0.3 m Figure 6. Intraformational mudchips within lower 21 Frontier unit near Cody. Length of the hammer is 0.3 m Figure 7. Wave-rippled and irregular bedding 22 surfaces within the lower Frontier unit near Buffalo Bill Reservoir, Cody. The coin is 30 mm in diameter Figure 0. Low-angled, inclined stratification in 23 lower Frontier sandstones and siltstones. These often show truncation surfaces that cut across other laminae sets. Meeteetse, Bighorn Basin. Length of the hammer is 0.3 m vil Figure 9. Black chert-pebble conglomerate within 24 the Peay sandstone (lower Frontier unit) exposed near Greybull. Note well-preserved wood fragment. The coin is 30 mm Figure 10. Polished rock slab showing chert-pebble 26 conglomerate (Peay sandstone) resting on profusely bioturbated sandstone near Shell Figure 11. Elongate and radial burrows in the Peay 27 sandstone exposed near Alkali. These are typical Asterosoma ichnofossil. The pen is 14 cm long Figure 12. Long and horizontal burrows in the Peay 28 sandstone near Greybull. These are typical Telchlchnvs Ichnofossil assemblage. The coin is 30 mm in diameter Figure 13. Exceptionally large sideritic 31 concretionary horizon in the uppermost Peay sandstone near Greybull. These are key stratigraphie markers in the field. The diameter of the individual concretion is about 4 meters Figure 14. Low-angled, cross-stratified sandstone 36 in Torchlight sandstone (Lithotype "d" of the middle Frontier unit) near Tensleep. The pen is 14 cm long Figure 15. Torchlight sandstone showing its 38 irregular contact relationship with overlying polymictic conglomerate. Alkali, Bighorn Basin. The pen is 14 cm long Figure 16. Beds of lenticular sandstone with 39 thin carbonaceous brown shale and lignite stringers within the middle Frontier unit (Lithotype"b") exposed near Cody. The length of the hammer is 0.3 m Figure 17. The middle Frontier unit near Kaycee, 40 Powder River Basin. The sandstone shows reverse grading and contains granule vili sized chert clast Figure 18. Binary plot of andesite clast diameter 43 (cm) vs distance (km). The transect from Cody to Kaycee shows concentration of largest clasts in Greybull-Basin area. Notice very crude correlation between andesite clast size and distance. The clast size values represent an average diameter for scores of andesite clasts measured in each localities Figure 19. Distinctive northwest-southeast 44 trending andesite clasts dispersal within both Bighorn and Powder River Basins. Notice apparent absence of andesite clasts to the southwest and northeast directions. 8, 15, 20/ and 25 represent average andesite clast diameter (in cm) in a particular location Figure 20. Remarkably flat lamination grading into 48 ripple-lamination within the upper Frontier sandstone near Thermopolis. The length of the hammer is 0.3 m Figure 21. Map showing distribution of the 59 Cretaceous seaway within interior of continent. (After Weimer, 1986) Figure 22. Relationships between levels of 61 bioturbation, depth, and oxygenation in an oxygen-stratified basin. (After Rhoads and Morse, 1971) CHAPTER II. Figure 23. Binary axial-ratio plot (c/b vs b/a; 100 where a ; longest axis, b : intermediate axis, and c : shortest axis) of Torchlight andesite clasts measured from various localities within Bighorn and Powder