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The Composition of the Lunar Crust: Radiative Transfer Modeling and Analysis of Lunar Visible and Near-Infrared Spectra

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The Composition of the Lunar Crust: Radiative Transfer Modeling and Analysis of Lunar Visible and Near-Infrared Spectra THE COMPOSITION OF THE LUNAR CRUST: RADIATIVE TRANSFER MODELING AND ANALYSIS OF LUNAR VISIBLE AND NEAR-INFRARED SPECTRA A DISSERTATION SUBMITTED TO THE GRADUATE DIVISION OF THE UNIVERSITY OF HAWAI‘I IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN GEOLOGY AND GEOPHYSICS DECEMBER 2009 By Joshua T.S. Cahill Dissertation Committee: Paul G. Lucey, Chairperson G. Jeffrey Taylor Patricia Fryer Jeffrey J. Gillis-Davis Trevor Sorensen Student: Joshua T.S. Cahill Student ID#: 1565-1460 Field: Geology and Geophysics Graduation date: December 2009 Title: The Composition of the Lunar Crust: Radiative Transfer Modeling and Analysis of Lunar Visible and Near-Infrared Spectra We certify that we have read this dissertation and that, in our opinion, it is satisfactory in scope and quality as a dissertation for the degree of Doctor of Philosophy in Geology and Geophysics. Dissertation Committee: Names Signatures Paul G. Lucey, Chairperson ____________________________ G. Jeffrey Taylor ____________________________ Jeffrey J. Gillis-Davis ____________________________ Patricia Fryer ____________________________ Trevor Sorensen ____________________________ ACKNOWLEDGEMENTS I must first express my love and appreciation to my family. Thank you to my wife Karen for providing love, support, and perspective. And to our little girl Maggie who only recently became part of our family and has already provided priceless memories in the form of beautiful smiles, belly laughs, and little bear hugs. The two of you provided me with the most meaningful reasons to push towards the "finish line". I would also like to thank my immediate and extended family. Many of them do not fully understand much about what I do, but support the endeavor acknowledging that if it is something I’m willing to put this much effort into, it must be worthwhile. I am forever thankful to my research advisor, Dr. Paul Lucey. It is difficult to calculate how grateful I am that he granted me the opportunity to be a part of his scientific world of lunar geology and spectroscopy. It has been a privilege to learn from a man with a unique blend of scientific ambition and creativity tempered with a large dose of humor, extraordinary patience, and solid family values. I do not remember a time when he was more critical of me than he was of himself. Although naïve, I can only hope I may one day measure up to at least his example if not his status as a scientist. Thank you to my remaining committee members Dr. Jeff Taylor, Dr. Jeff Gillis-Davis, Dr. Patty Fryer, Dr. Eric Hochberg, and Dr. Trevor Sorensen. I simply couldn’t have requested a better, more fun, or sensible group of scientific evaluators. I would also like to thank Dr. Will Koeppen, Dr. Brett Denevi, Dr. Samuel Lawrence, Dr. Meryl McDowell, Dr. Miriam Riner, Christopher Hamilton, and Donovan Steutel for their council and friendship during varying stages of this degree. I hope these friendships both personally and professionally continue indefinitely into the future. iv ABSTRACT This dissertation has two focuses: (1) the evaluation and validation of algorithms used for analysis of lunar visible and near-infrared data sets, and (2) the determination of lunar surface and sub-surface crustal composition by virtue of these algorithms. To that end, the results and interpretation reported herein further enhance knowledge of lunar ferroan anorthosite (FAN) and magnesium-suite (Mg-suite) mineralogy, chemistry, and distribution on and in our Moon’s crust. v TABLE OF CONTENTS ACKNOWLEDGEMENTS ....................................................................................... IV ABSTRACT .............................................................................................................. V TABLE OF CONTENTS ........................................................................................... VI LIST OF TABLES ................................................................................................... IX LIST OF FIGURES ................................................................................................... X LIST OF ABBREVIATIONS AND VARIABLES ..................................................... XIII CHAPTER 1. INTRODUCTION .................................................................................1 OVERVIEW .................................................................................................................................................. 2 BASIC LUNAR PETROLOGY, A BRIEF SUMMARY ......................................................................................... 3 OUTLINE OF STUDIES ................................................................................................................................. 6 Modeling of lunar highlands spectral classes ................................................................................. 6 The composition of impact crater central peaks ............................................................................ 6 Modeling of lunar mare and highland soils: .................................................................................. 8 Modeling of lunar nearside, near-infrared telescopic spectra..................................................... 9 CHAPTER 2. RADIATIVE TRANSFER MODELING OF LUNAR HIGHLANDS SPECTRAL CLASSES AND RELATIONSHIP TO LUNAR SAMPLES ......................... 11 ABSTRACT ................................................................................................................................................. 12 INTRODUCTION ......................................................................................................................................... 13 APPROACH ................................................................................................................................................ 15 RESULTS .................................................................................................................................................... 27 Mineralogy of Lunar Spectral Classes ........................................................................................... 29 Analysis of Bullialdus Crater ........................................................................................................... 36 DISCUSSION .............................................................................................................................................. 47 CONCLUSIONS ........................................................................................................................................... 50 FUTURE WORK ......................................................................................................................................... 51 ACKNOWLEDGEMENTS .............................................................................................................................. 52 CHAPTER 3. THE COMPOSITIONAL VARIATIONS OF THE LUNAR CRUST: RESULTS FROM RADIATIVE TRANSFER MODELING OF CENTRAL PEAK SPECTRA ............................................................................................................... 53 ABSTRACT ................................................................................................................................................. 54 INTRODUCTION ......................................................................................................................................... 55 APPROACH ................................................................................................................................................ 57 Modeling Crustal Thickness ............................................................................................................. 57 Modeling Peak Depth of Origin ....................................................................................................... 59 Determination of Central Peak Origin in the Crust ..................................................................... 60 Spectral Analysis Approach ............................................................................................................ 62 RESULTS .................................................................................................................................................... 66 Analysis of Finsen central peak ...................................................................................................... 66 vi Central Peak Composition Relative to Lunar samples ................................................................ 66 Composition relative to crustal thickness ...................................................................................... 75 Composition relative to peak origin ............................................................................................... 75 Composition of peaks laterally ........................................................................................................ 77 DISCUSSION .............................................................................................................................................. 81 CONCLUSIONS ........................................................................................................................................... 85 FUTURE WORK ......................................................................................................................................... 86 ACKNOWLEDGEMENTS .............................................................................................................................
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