CONTROLS ON ORE DEPOSffiON IN THE LAMOITE SANDSTONE, GOOSE CREEK MINE, INDIAN CREEK SUBDISTRICT, SOUTHEAST MISSOURJ TIIlS THESIS IS DEDICATED TO MY PARENTS, ERNEST EARL AND RUTH W. TAYLOR, ANDOSKAR CONTROLS ON ORE DEPOSITION IN THE LAMOTTE SANDSTONE, GOOSE CREEK MINE, INDIAN CREEK SUBDISTRICT, SOUTHEAST MISSOURI BY GAY NELL GUTIERREZ, B.S. THESIS Presented to the Faculty of the Graduate School of The University of Texas at Austin in Partial Fulfillment of the Requirements for the Degree of MASTER OF ARTS THE UNlVERSITY OF TEXAS AT AUSTIN AUGUST 1987 ACKNOWLEDGMENTS I would like to thank my supervisor, Dr. J. Richard Kyle for suggesting this thesis and making arrangements with St. Joe Minerals Corporation for access to the Indian Creek mines and drill cores. I am also indebted to him for taking time to visit Goose Creek mine while I was doing field work. Many of his suggestions during this visit proved to be invaluable since the mine was closed and allowed to flood shortly after I finished my field work. Most commendable however, he has remained my supervisor for this extended period of study, when the normal supervisor would have looked for a more energetic student. Ors. Lynton S. Land and Earle F. McBride served as committee members. They read the thesis and made many valuable suggestions. Dr. Harry H. Posey of the Bureau of Economic Geology served as an informal committee member, "cheerleader", and "coach". He read the first draft of the thesis, and his knowledge of the Southeast Missouri lead-zinc district made his corrections and comments extremely useful. I am indebted to St. Joe Minerals Corporation, especially Paul Gerdemann, for permission to study the Goose Creek deposit and for providing access to the Indian Creek mines, drill cores and mine maps. James Pettus, former Indian Creek mine geologist, showed me around the Indian Creek mines and generously shared his knowledge of the local geology. Gary Miller served as my guide while underground. He also helped me carry samples, and kept my camera dry. IV Richard Moralas made many of my polished thin-sections and provided assistance and constructive criticism for those that I made. Oskar Gutierrez and Rick Ozment assisted in computer mapping, and Pat Bobeck and Kitty Milliken helped me use the microprobe. For those illustrations that "look professional", the drafting was done by Kerza Prewitt and Joel Lardon. Partial support for field work was provided by the Geology Foundation. Lastly, I would like to thank Drs. Rob Finley, Steve Fisher, Shirley Dutton, Jon Price, and Ronit Nativ of the Bureau of Economic Geology for providing me with employment and the opportunity to work in different fields of geology while pursuing this degree. This thesis was submitted to the Committee in July 1987. v ABSTRACT The Indian Creek subdistrict is the northernmost mineralized area in the Southeast Missouri district and is unique because ore-grade concentrations of sulfides occur within the Lamotte Sandstone. The Lamotte Sandstone-hosted Goose Creek mine is located on the northern end and the Bonneterre Dolomite-hosted Indian Creek mine on the northwestern side of a N30°E-trending, Precambrian rhyolite ridge. A saddle on the northern end of the ridge separates the Indian Creek subdistrict from another probable high along the same trend to the north. Lamotte deposition was influenced by pre-Lamotte basement topography, and local thickness ranges from 0 where it pinches out again st the ridge to over 100 ft toward the basin. It is comprised of a thin, discontinuous basal cobble conglomerate overlain by a medium-grained, moderately to poorly soned, well-rounded quanzarenite. Fourteen authigenic minerals, plus hydrocarbons cement the Lamotte Sandstone at Goose Creek in the following paragenetic sequence: dolomite - framboidal pyrite - marcasite - cuboctahedral pyrite - bravoite - bladed marcasite - pyrite - quartz dissolution - brecciation - siegenite - marcasite - dolomite - brecciation - chalcopyrite - quartz dissolution - sphalerite - galena (cuboctahedral) - quartz - galena (cubic) - dolomite - gypsum - hydrocarbon - kaolinite - illite - calcite - • hydrocarbon. Primary and secondary porosity in the Lamotte vary between 1 and 20 volume percent and authigenic cements account for up to 35 volume percent of the sandstone. Quartz overgrowths are the most common cement in the Lamotte Sandstone at Goose Creek, comprising from 1 to 11 volume percent of the rock. Galena is the most abundant sulfide and commonly occurs in 1 to 3 mm blebs, V1 averaging 3-4 volume percent. Chalcopyrite averages 0.5 volume percent, but high grade concentrations reach 8-10 volume percent locally. Sulfides in the Lamotte Sandstone in the Indian Creek subdistrict commonly occur within 40 ft of the Bonneterre-Lamotte contact, with the highest concentrations within 20 ft or less of the contact Structure maps of the lead- and copper- bearing-zones mimic the basement topography, suggesting that the Precambrian basement was the major controlling factor on ore deposition in the Indian Creek subdistrict. Vertical tubes of sulfides, which cross-cut bedding near the Lamotte pinchout in the Goose Creek mine, suggest that the ore-bearing fluids moved through the sandstone aquifer until the pinchout forced them into the overlying Bonneterre. There the fluids were channeled through the grainstone-algal reef complex along the N30°E-trending Precambrian ridge. Limited fluid inclusion data for Bonneterre-hosted sphalerite indicate that the mineralizing fluid was a Na-Ca-0 brine with temperatures between 105 and 120° C. Vll TABLE OF CONTENTS ~ INTRODUCTION 1 General Information 1 Location of Study Area 3 History of Southeast Missouri and Indian Creek 3 Purpose of This Study 5 Methods of Study 6 Previous Work 7 REGIONAL GEOLOGY 9 General Information 9 Precambrian Basement Rocks 9 Upper Cambrian Stratigraphy 12 Introduction 12 Lamotte Sandstone 12 Bonneterre Formation 18 Davis Formation 20 Structural Geology 20 INDIAN CREEK STRUCTURE 23 LAMOTTE COMPOSmON AND DEPOSmO~AL HISTORY 28 General Information 28 Basal Cobble Conglomerate 28 Sandstone 32 Detrital composition 32 Introduction 32 Quartz 34 Sedimentary rock fragments 35 Volcanic rock fragments 37 Fossils 39 Grain size, sorting and roundness 39 Lamotte-Bonneterre Transition 40 Structural Influence On Deposition 41 Sedimentary Structures and Depositional Environment 41 Cross-bedding 41 Interbedded shales and carbonates 41 Ripup clasts 42 Soft-sediment deformation 44 Depositional environment 44 Ylll Page DIAGENESIS 46 Sediment Compaction And Pressure Solution 46 Interlocking quartz grains 46 Stylolites 47 Pressure solution associated with phosphorite 49 Authigenic Cements 49 Sulfides 49 Pyrite and marcasite 49 Grue~ 52 Chrucopyrite 54 Siegenite 57 Bravoite 60 Sphruerite 60 Non-sulfides 64 Quartz 64 Dolomite 64 Kaolinite 65 Feldspar 67 Gypsum 67 Illite 68 Calcite 68 Hydrocarbons 68 Quartz Dissolution and Brec.tjanwi 68 Paragenetic Sequence 72 Comparison with other studies in Southeast Missouri 74 Goose Creek mine 7 4 Lamotte Sandstone 76 Southeast Missouri disrrict 78 Comparison with other sandstone -hosted deposits 80 Cement Textures 82 Between cements and sedimentary structures 82 Between cements 82 MINERALIZATION 85 Ore Disrribution 85 Minerruization Controls 86 Introduction 86 Sedimentary structures and locru sulfur sources 86 Lamotte pinchout and Bonneterre permeability 88 Precambrian basement topography 92 Nature of Ore-forming Solutions 100 ix Sources of Metals and Sulfur 102 Lead and sulfur 102 Copper, cobalt, and nickel 104 Transporting Mechanism 105 Timing of Ore Deposition 106 Other Sandstone-hosted Base Metal Deposits 107 CONCLUSIONS 110 REFERENCES 112 VITA 119 x LIST OF TABLES Table Page 1. Scanning electron microscope analyses of phosphorites and calcium phosphate fossil fragments. 38 2. Microprobe analyses of siegenite. 59 3. Microprobe analyses of bravoite. 63 4. Fluid inclusion analyses of sphalerite. 101 5. Characteristics of sandstone-hosted Pb-Zn-Cu and carbonate-hosted Pb-Zn deposits, and the Goose Creek deposit. 108 xi LIST OF FIGURES Figure 1. Generalized geology of the Southeast Missouri district. 2 2. Precambrian basement structure map of the Indian Creek subdistrict with an outline of Indian Creek and Goose Creek mines. 4 3. Basement-rock types in Missouri. 11 4. Generalized stratigraphic column for Upper Cambrian strata in the Southeast Missouri lead district showing schematic position of the ore zone in the Indian Creek subdistrict. 13 5. Location of Precambrian and Lamotte outcrops in the St. Francois Mountains. 14 6. Lamotte isopach map for Missouri and Illinois. 15 7. Precambrian basement structure map for Missouri. 21 8. Precambrian basement structure map for the Indian Creek subdistrict. 24 9. Basement structure on the northern flank of the St. Francois Mountains based on aeromagnetic data. 25 10. Schematic evolution of the Precambrian basement structure and topography in Indian Creek subdistrict 27 I la. lsopach map of the Lamotte Sandstone at Indian Creek. 29 llb. Geologic cross-section A-A' of the Indian Creek ridge showing the relationship between basement structure, Lamotte Formation, and lead mineralization. 30 I le. Geologic cross-section B-B' of the Indian Creek ridge showing the relationship between basement structure, Lamotte Formation, and lead mineralization. 31 12. Plot of quartz, feldspar, and rock fragments in the Lamotte Sandstone at Goose Creek. 33 XU 13. Photomicrograph of a phosphorite and quartz clast in the ~ Lamotte quartzarenite.