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The Attributes and Formation Mechanisms of Kallistos Vallis, Venus by Derek A. Berman, B.S. A Thesis In Geosciences Submitted to the Graduate Faculty of Texas Tech University in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE Approved David W. Leverington, Ph.D. Chair of Committee Haraldur R. Karlsson, Ph.D. Harold Gurrola, Ph.D. Dr. Mark Sheridan Dean of the Graduate School December, 2020 Copyright 2020, Derek A. Berman Texas Tech University, Derek A. Berman, December 2020 ACKNOWLEDGMENTS I would like give my heartfelt gratitude and thanks to all my committee members. I would like to thank Dr. David Leverington for working with me these past years to accomplish this research and further my knowledge of planetary geology, geomorphology, and remote sensing. I hope this will be just the start to future collaborations, and that in 20 years we can still consider each other friends and colleagues in science. Thank you to Dr. Hal Karlsson for all your thoughtful comments and feedback on my thesis and a thank you to Dr. Harold Gurrola for serving on my thesis committee. I would also like to thank Lucia Barbato, Cameron Griffith, and Dr. Callum Hetherington for all the thoughtful advice, mentoring, and academic training. The three of you definitely helped to enrich my academic experience at TTU. The past several years have represented a huge personal growth period, full of challenges and triumphs. I want to thank all my friends and family members who lent me their undying support and motivation. I especially want to thank my sister Nicole, who was with me through the toughest of times, and my friends Giovanni, Luka, and Matteo, as well as all the members of the “Italian Club”, for your camaraderie and kind words of encouragement. Finally, I would like to thank the Texas Tech University Department of Geosciences and Texas Tech University Graduate School for all of the additional financial support that was provided over these last few years. Without this support I would have never been able to commit the necessary time required to complete the research that has led to my successful thesis defense. ii Texas Tech University, Derek A. Berman, December 2020 TABLE OF CONTENTS ACKNOWLEDGMENTS..................................................................................... ii ABSTRACT............................................................................................................ v LIST OF TABLES .............................................................................................. vii LIST OF FIGURES ........................................................................................... viii I. INTRODUCTION.............................................................................................. 1 1.1 General Overview ....................................................................................... 1 1.2 Previous Studies .......................................................................................... 2 1.3 Purpose of Study ......................................................................................... 2 II. BACKGROUND .............................................................................................. 4 2.1 Overview of Early Historical Observations ................................................ 4 2.2 Modern Obsrvations and Magellan Overview ............................................ 5 2.3 Venusian Geological and Physiographic Units ........................................... 7 2.4 Geologic Time Periods ................................................................................ 9 2.5 Analog Channel Systems on Mercury, Earth, and the Moon .................... 11 2.5.1. Mercurian Channels ........................................................................ 13 2.5.2. Lunar Channels ............................................................................... 16 2.5.3. Terrestrial Channels ........................................................................ 19 2.6 Channel Systems on Venus ....................................................................... 21 2.6.1. Compound and Complex Channels ................................................. 22 2.6.2. Canali .............................................................................................. 23 2.6.3. Sinuous Rilles ................................................................................. 24 2.7 Regional Geologic Setting of Kallistos Vallis .......................................... 25 2.8 Overview of Kallistos Vallis ..................................................................... 30 III. MORPHOLOGICAL CHARACTERIZATION OF KALLISTOS VALLIS ................................................................................................................ 40 3.1 Overview of Methodology ........................................................................ 40 3.2 Data Acquisition ....................................................................................... 40 3.3 Topographic Overview ............................................................................. 41 3.4 Cross-sectional Profiles ............................................................................. 42 iii Texas Tech University, Derek A. Berman, December 2020 3.5 Longitudinal Profiles ................................................................................. 52 3.6 Channel Area Measurements .................................................................... 58 IV. ESTIMATION OF FLOW CONDITIONS AND INCISION RATES ....61 4.1 Mechanical Incision Parameters ............................................................... 61 4.2 Thermal Incision Parameters..................................................................... 64 4.3 Estimates of Flow Conditions ................................................................... 68 4.3.1. Flow Velocity Estimates ................................................................. 68 4.3.2. Total Discharge Estimates .............................................................. 69 4.3.3. Reynolds Number Estimates ........................................................... 70 4.4 Estimates of Mechanical and Thermal Incision ........................................ 71 4.4.1. Mechanical Calculations ................................................................. 71 4.4.2. Thermal Calculations ...................................................................... 72 4.4.3. Dynamic Viscosity Parameter Space Calculations ......................... 73 V. ESTIMATION OF MINIMUM LAVA VOLUMES REQUIRED FOR FORMATION OF KALLISTOS VALLIS ....................................................... 75 5.1 Elementary Thermal Determination of Minimum Lava Volume Effused at Kallistos Vallis ............................................................................................ 76 5.2 Discharge-Related Determination of Minimum Lava Effused at Kallistos Vallis ............................................................................................................... 79 VI. DISCUSSION ................................................................................................ 81 VII. CONCLUSIONS ......................................................................................... 90 BIBLIOGRAPHY ............................................................................................... 92 APPENDICES A. SOURCE CODE FOR THE ITERATIVE CALCULATION OF MECHANICAL INCISION RATES .............................................................. 107 B. SOURCE CODE FOR THE ITERATIVE CALCULATION OF THERMAL INCISION RATES ...................................................................... 111 C. SOURCE CODE FOR AREA CALCULATIONS .................................... 116 iv Texas Tech University, Derek A. Berman, December 2020 ABSTRACT Kallistos Vallis is a large volcanic channel system located in the Ammavaru volcanic province of Venus. The system extends more than 1200 km downslope from a complex topographic depression, terminating at distal plains characterized by distributary channels that emplaced extensive volcanic flows with estimated total volumes of thousands of cubic kilometers. Some channel reaches of Kallistos Vallis are as wide as 30 km and are in places characterized by the presence of prominent streamlined erosional residuals about which the system anastomoses. Cross-sectional and longitudinal profiles generated for Kallistos Vallis using low-resolution Magellan altimetry data do not constrain the form of the system effectively, beyond demonstrating that topographic relief across channels is generally at least tens of meters, and the kilometer-scale longitudinal slopes that characterize the system are generally well below 1°. The main Kallistos Vallis system has a surface area of ~41,000 km2, roughly 20% of which is comprised of the channel reaches that form the westernmost and central parts of the system, and 80% of which forms the eastern volcanic plains and related distributary channel reaches. The head depression of Kallistos Vallis is interpreted as the surface expression of a deeply-rooted igneous plumbing system that conveyed large volumes of mafic or ultramafic magma to the surface from subcrustal depths. The flow conditions potentially associated with development of the channel system were estimated on the basis of known constraints of the Venusian environment and the nature of volcanic analogs of the inner solar system. Flows with depths of 5 m and 20 m and viscosities of 1 Pa s would have been fully turbulent on essentially