Louisiana State University LSU Digital Commons LSU Master's Theses Graduate School 2006 Muscovite pseudomorphs after staurolite as a record of fluid infiltration during prograde metamorphism Jennifer Kaye Whittington Louisiana State University and Agricultural and Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_theses Part of the Earth Sciences Commons Recommended Citation Whittington, Jennifer Kaye, "Muscovite pseudomorphs after staurolite as a record of fluid infiltration during prograde metamorphism" (2006). LSU Master's Theses. 3854. https://digitalcommons.lsu.edu/gradschool_theses/3854 This Thesis is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Master's Theses by an authorized graduate school editor of LSU Digital Commons. For more information, please contact [email protected]. MUSCOVITE PSEUDOMORPHS AFTER STAUROLITE AS A RECORD OF FLUID INFILTRATION DURING PROGRADE METAMORPHISM A Thesis Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Master of Science in The Department of Geology and Geophysics by Jennifer Kaye Whittington B.S., Louisiana State University, 2002 August, 2006 ACKNOWLEDGMENTS I would like to express my gratitude and appreciation to the faculty and staff in the Department of Geology and Geophysics at Louisiana State University, in particular to Dr. Barb Dutrow, Dr. Darrell Henry, and Dr. Jeff Hanor of my thesis committee for their advice and support. Another sincere thanks goes to Dr. Dutrow for her commitment not only to her work, but also to her students, whose appreciation to her often goes unsaid but is deeply felt. Many thanks go to Dr. Xiaogang Xie of Louisiana State University for his help and guidance in the lab, and for the hours spent toiling with my requests. My thanks go to Dr. C. Tom Foster of the University of Iowa for help with the use of his SEG 93 program. A special thanks goes to Rick Young (you rock!) and Corine Armstrong from LSU for all their preparations. And, of course, I thank my loving husband, Arin, for his patience, reassurance, and for keeping my spirits high; and to Adam for being so understanding when Mommy has to concentrate on her work. I can’t wait til we can laugh at Bobobobobobobo together. I would also like to thank those who helped fund this research, the Dept. of Energy, Basic Energy Sciences/EPSCoR with grant DE-FG02-03ER-46041 to Dutrow; and special funding from the Shreveport Geological Society, and Shell Oil Company. And finally, my warmest thanks to the previous workers in this region whose research has enlightened us all and lead us here. ii TABLE OF CONTENTS ACKNOWLEDGMENTS ............................................................................................ ii LIST OF TABLES.........................................................................................................v LIST OF FIGURES ..................................................................................................... vi ABSTRACT...................................................................................................................x INTRODUCTION .........................................................................................................1 Background...............................................................................................................3 Geologic Setting..................................................................................................3 Study Area ..........................................................................................................4 Previous Work on Staurolite Pseudomorphs ....................................................10 METHODS ..................................................................................................................12 Scanning Electron Microscope Analyses...............................................................12 Backscatter Electron Images............................................................................12 X-ray Maps ......................................................................................................14 Modes...............................................................................................................16 Cathodoluminescent Images ............................................................................21 Electron Microprobe Analysis ..............................................................................23 Geothermometry ...................................................................................................25 Textural Modeling ................................................................................................25 RESULTS ....................................................................................................................31 Petrography............................................................................................................31 Mineral Modes.......................................................................................................43 Pseudomorph Mineral Modal Types................................................................48 Muscovite-Rich Pseudomorphs .......................................................................53 Plagioclase Muscovite Pseudomorphs.............................................................58 Sillimanite Plagioclase Muscovite Pseudomorphs ..........................................62 Quartz Muscovite Pseudomorphs ....................................................................65 Electron Microprobe Analyses ..............................................................................65 Cathodoluminescence ............................................................................................79 Geothermometry ....................................................................................................85 Textural Modeling .................................................................................................92 Muscovite-Rich Pseudomorphs .......................................................................93 Plagioclase Muscovite Pseudomorphs.............................................................97 Sillimanite Plagioclase Muscovite Pseudomorphs ........................................100 Quartz Muscovite Pseudomorphs ..................................................................103 DISCUSSION..........................................................................................................106 Evidence for Fluid Infiltration .............................................................................110 iii CONCLUSIONS........................................................................................................115 REFERENCES ..........................................................................................................116 VITA..........................................................................................................................119 iv LIST OF TABLES 1. Stratigraphy of the Farmington Quadrangle, Maine...................................................8 2. Mineral Formulae and Abbreviations .......................................................................13 3. Mineral Standards Used for Electron Microprobe Analyses ....................................24 4. Summary of Mineral Compositions Used in the Textural Modeling .......................29 5. Example of SEG 93 Input Data Screen.....................................................................30 6. Mineral Modal Amounts (%) in the Pseudomorphs and the Matrix as Determined by Image Analyses................................................................................44 7. Mineral Analyses of Representative Biotite .............................................................71 8. Mineral Analyses of Representative Muscovite .......................................................74 9. Mineral Analyses of Representative Plagioclase......................................................76 10. Ti-in-biotite Geothermometer (Henry et al., 2005) ..................................................91 11. Comparison of the Average Observed Mineral Modes and SEG 93 Calculated Mineral Modes..........................................................................................................94 v LIST OF FIGURES 1. A Generic P-T-t Path for a Compressional Tectonic Event..............................................2 2. Metamorphic Map of West Central Maine .......................................................................6 3. Sample Locations on a Geologic Map of the Lower Farmington Quadrangle, Maine.....9 4. Sample 167 X-ray Image of Aluminum..........................................................................15 5. Sample 167 Merged Na, K, and Si X-ray Images...........................................................17 6. Sample 167 Final Composite RGB X-ray Image ...........................................................18 7. Comparison of Quartz and Plagioclase Images Clarify the Reasoning Behind the Use of X-Ray Maps .........................................................................................................19 8. Mineral Modes (%) Used in the Textural Modeling.......................................................27 9. Plane Light Photomicrograph of a Muscovite Pseudomorph after Staurolite Still Containing