Lunar craters with cracked floors Item Type text; Thesis-Reproduction (electronic) Authors Weller, Roger Nelson, 1944- Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 24/09/2021 00:53:28 Link to Item http://hdl.handle.net/10150/347802 LUNAR CRATERS WITH CRACKED FLOORS by Roger Nelson Weller A Thesis Submitted to the Faculty of the DEPARTMENT OF GEOSCIENCES In Partial Fulfillment of the Requirements For the Degree of MASTER OF SCIENCE In the Graduate, College THE UNIVERSITY OF ARIZONA 19 7 2 STATEMENT BY AUTHOR This thesis has been submitted in partial fulfillment of re­ quirements for an advanced degree at The University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library. Brief quotations from this thesis are allowable without special permission, provided that accurate acknowledgment of source is made. Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his judg­ ment the proposed use of the material is in the interests of scholarship. In all other instances, however, permission must be obtained from the author. APPROVAL BY THESIS DIRECTOR This thesis has been approved on the date shown below: SPENCER R. TIT LEY Date Professor of Geosciences ACKNOWLEDGMENTS I would like to express my sincere gratitude to my many friends and colleagues who have donated much valuable time in assisting me with this thesis. I am especially indebted to Dr. S. R. Titley for criti­ cally reviewing the thesis, to Dr. W. B. Bull for stressing the develop­ ment of interpretative criteria, and to Dr. R. G. Strom for evaluating the feasibility of the proposed mechanisms. Other workers from whose constructive criticisms and us.eful suggestions I have greatly benefited are E. A. Whitaker and Drs. P. E. Damon, W. K. Hartmann, G. P. Kuiper, W.C. Lacy, and E. B. Mayo. I would also like to thank my fellow students, J. Cannon, N. Colburn, R. Holcomb, P. Kresan, S. Larson, D. Vukobratovich, and H. Welhener not only for allowing me to sound out my ideas but also for their assitance in typing and in the preparation of photographs. I am especially indebted to my parents for their kind encourage­ ment in my studies throughout my youth and for their faith in me. I would also like to acknowledge my thankfulness to two people who were influ­ ential in directing my interest at any early age toward geology: Mr. Walter Bone and my grandmother, Mrs. Arthur Weller. A portion of this study was financed by a summer trainee ship in 1970 from the National Science Foundation. TABLE OF CONTENTS Page LIST OF ILLUSTRATIONS. .. vil LIST OF TABLES .................... xii ABSTRACT. ....................... .... xiii 1. INTRODUCTION........................... 1 The Problem . .................................... 1 The Approach . 1 Materials and Conventions ............. 4 2 . ' DESCRIPTION AND GENERAL NATURE OF THE CRACKS . 5 Crack W idths ............................................. 5 Maximum and Mean Maximum Crack Widths .... 5 Mean Crack W idth ...................................................... 8 Minimum Crack Width . 8 Crack Depth and Wall S l o p e s ................................ 9 Summary of Crack Cross-sectional P r o f ile s...................... 12 Total Crack Lengths and Crack Density ........ 13 Crack Direction .................. 14 Rose Diagrams. 16 Crater-centered Directional C ontrol............................ 20 Crack Patterns......................................... 21 Pitatus Crack Pattern........................... 21 Humboldt Crack Pattern......................................... 29 Petavius Crack Pattern......................................... 29 Alphonsus Crack Pattern ............ 29 Lavoisier H Crack Pattern . 29 Wurzelbauer Crack Pattern . .......... 38 Summary of the Crack Patterns . .................. 38 Crack Configurations.................................... 38 Summary of Crack Descriptions ........... 40 3. CLASSIFICATION AND GENESIS OF THE LUNAR RILLES . 46 Sinuous Rilles...................... 46 Wide-floored Rilles . 52 Irregular Rilles ...................... 60 Lineament Rilles......................................... 64 Cracks . ...... ...... 66 iv V TABLE OF CONTENTS— Continued • . Page 4. CRATER-FLOOR MATERIALS . .............. 69 Original Crater-floor Materials . 69 Dark Secondary Crater-floor Fillings 72 Light-colored Secondary Crater Fillings ........ 79 Small-scale Features of Possible Volcanic Origin. 85 - Summary of Crater-floor Materials .......... 92 5. CRATER FLOOR AND RIM MORPHOLOGY , . , . .... 93 Crater-floor Morphology . .... 93 Crater-rim Morphology . 101 6. REGIONAL CONTROL OF CRATERS WITH CRACKED FLOORS . 109 Size-frequency Distribution of Lunar Craters with Cracked Floors ....................................................... 109 Distribution of Craters with Cracked Floors by Latitude and Longitude...................... 112 Distribution by Latitude .' ............ 112 Distribution by Longitude . .. ...... 113 Distribution of the Craters with Cracked Floors in Relation to the Maria. 117 Formation of the Circular Maria ......... 119 Formation of the Irregular Maria . ......................... 126 Lineaments Related to Craters with Cracked Floors . 127 Summary ........................... 130 7. TERRESTRIAL ANALOGUES ................ 133 Resurgent Calderas. ................................ 134 Terminology and General Characteristics ......... 134 Valles Caldera. ........................... 136 Timber Mountain Caldera . ..... 138 Turkey Creek Caldera. ......... .... 142 Comparison between Terrestrial Resurgent Calderas and Lunar Craters with Cracked Floors . 143 Cauldron Block vs Crater Filling ............ 145 Physical Characteristics of Magmas. Associated with Lunar Craters with Cracked Floors .... .. 146 Martian Analogues to the Lunar Craters with Cracked Floors . .... 148 vi TABLE OF CONTENTS--Continued Page 8„ A GENERALIZED MODEL FOR THE FORMATION OF LUNAR CRATERS WITH CRACKED FLOORS ........ 150 Crater Formation ...................... ........... 150 Crater Fillings................................ 154 Development of the Cracks ^ . .... 157 Implications.. 159 APPENDIX I: LUNAR CRATERS WITH CRACKED FLOORS . 161 APPENDIX II: WIDTH MEASUREMENTS OF CRACKS . 165 APPENDIX III: DEGREE OF CRACKING. ......... 168 APPENDIX IV: CRACK PATTERNS ............. 171 REFERENCES. ..................... 173 LIST OF ILLUSTRATIONS Figure Page 1.' The Lavoisier Group of Craters with Cracked Floors . 2 2. Crater Palmier! ...... • • • • . V ...... 3 3. Maximum and Mean Maximum Crack Width Values Plotted vs Crater Diameter ............. 6 4. Mean and Minimum Crack Width Values Plotted vs Crater Diameter . .... „ ... 7 5. Hypothetical Models of Shadow Geometry in Cracks . 10 6. Close-up View of a Typical Crack within the Crater Gassendi ................. 11 7. Crater Density Plotted vs Crater Diameter ....... 15 8. Crater Hevelius . ...................... 17 9. Map of Hevelius Derived from Figure 8........ 18 10. Crater Lavoisier D . ........ .... 19 11. Semi-quantitized Crack Densities for Five Angular Crack Relationships . ..... 22 12. Graphic Summary of Idealized Major Crack Patterns . 23 13. Craters Pitatus, Hesiodus , and Wurzelbauer ...... 24 14. Map of Pitatus Region Derived from Figure 13 ..... 25 15. Craters Lavoisier and Lavoisier F ........... 26 16. The Lunar Far side Crater Chappell .......... 27 17. The Lunar Farside Basin-crater Oppenheimer . 28 18. Crater Humboldt. .................. 30 19. Map of Humboldt Derived from Figure 18 ....... 31 20. Crater Schluter . ................ 32 v ii . v iii LIST OF ILLUSTRATIONS—Continued Figure Page 21. Grater Petavius ................... 33 22. Craters Einstein "V" and Einstein " U" ......... 34 23. Crater Alphonsus 35 24. Map of Alphonsus Derived from Figure 23 . ..... 36 25. Crater Lavoisier H, ,, .... „ ........... 37 26. Eastern Portion of the Crater Floor in Humboldt ..... 39 27. Northeast Portion of the Crater Floor in Pitatus ..... 41 28. Crater Arzachel ........................ 42 29. Craters Rep sold and Repsold G ............ 43 30. Crater Messala ................... 44 31. Crater Posidonius .................. 48 32. Map of Posidonius Derived from Figure 31 . ...... 49 33. Schroter's Valley and the Cobra Head ......... 50 34. Wide-floored Rilles and Strings of Secondary Impact Craters near the Crater Ramsden ....... 54 35. Wide-floored Rilles Adjacent to the Crater Campanus . 55 36. Trace Configurations Characteristic of Wide-floored Rilles ................ 56. 37 . Eastern Margin of Mare Serenitatis .......... 58 38. Crater Hyginus and the Hygihus Rille . .... 59 39. Trace Configurations Characteristic of Irregular Rilles . 62 40. Wide-floored and Irregular Rilles near the Crater Triesnecker ................ 63 41. Lineament Rilles near the Crater Airy. ......... 65 42. Rough Floor Materials in the Central Portion of Tycho . 71 ix LIST OF ILLU STRAT IONS --Continued Figure Page 43. A Close-up View of the Northern Portion of the Crater Floor in TsioIkovsky . .. 74 44. Modified Cracks and Associated Dark Floor Materials Within the Crater Petavius . ^ . .- . 76 45. Dark-halo