The document summarizes research on explosive interactions between lava and water/ice on Earth and Mars. The researcher conducted fieldwork on volcanic rootless cones in Iceland formed by lava-water interactions and used this as an analog to study similar landforms on Mars, referred to as Tartarus Colles cone groups. Methods included geological mapping, statistical analysis of cone distributions, and thermodynamic modeling. Results showed the Martian cones were similarly clustered, suggesting explosive lava-water interactions formed them. This has implications for the possibility of underground ice deposits and past hydrothermal activity on Mars.

1. Christopher W. Hamilton [email_address] Hawai‘i Institute of Geophysics and Planetology, University of Hawai‘i Explosive Lava–Water Interactions on Earth and Mars Ph.D. Co-Advisor: Thor Thordarson Co-Authors: Lionel Wilson Ciarán Beggan Ph.D. Advisor: Sarah Fagents Acknowledgements National Aeronautics and Space Administration Icelandic Centre for Research National Science Foundation Geological Society of America Hawai ‘i Geographic Information Coordinating Council University of Hawai ‘i Graduate Student Organization

3. Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Explosive Lava–Water Interactions Earth: Hamilton CW , T Thordarson, and SA Fagents (2010a) Explosive lava-water interactions I: architecture and emplacement chronology of volcanic rootless cone groups in the 1783- 1784 Laki lava flow. Bulletin of Volcanology , 10.1007/s00445-009-0330-6. Hamilton CW , SA Fagents, and T Thordarson (2010b) Explosive lava-water interaction II: Self-organization processes among volcanic rootless eruption sites in the 1783-1784 Laki lava flow, Iceland. Bulletin of Volcanology , 10.1007/s00445-009-0331-5. Mars: Hamilton CW , SA Fagents, and L Wilson (2010c) Explosive lava-water interactions in Elysium Planitia, Mars: constraints on the formation of the Tartarus Colles cone groups. Journal of Geophysical Research , (in press). Hamilton CW , SA Fagents, and T Thordarson (2010d) Lava-ground ice interactions in Elysium Planitia, Mars: geomorphological and geospatial analysis of the western Tartarus Colles cone groups. Journal of Geophysical Research , (in review).

4. Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Introduction

5. Lake Mývatn, Iceland Volcano–H 2 O Interactions Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Volcanic Rootless Cones (VRCs)

6. Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Skaftá River, Iceland Volcanic Rootless Cones (VRCs)

7. VRC group in the Laki lava flow, Iceland Introduction Methods Results Discussion Conclusions Volcanic Rootless Cones (VRCs) Introduction Earth Mars Discussion Conclusions

9. Conceptual Model Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

10. Conceptual Model Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

11. Conceptual Model Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

12. Conceptual Model Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

13. Conceptual Model Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

14. Conceptual Model Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

15. Conceptual Model Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

16. Conceptual Model Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

17. Conceptual Model Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

18. Conceptual Model Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

19. Conceptual Model Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

20. Conceptual Model Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

21. Conceptual Model Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

22. Conceptual Model Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

23. Conceptual Model Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

24. Conceptual Model Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

25. Conceptual Model Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

26. Conceptual Model Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

27. Conceptual Model Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

28. Conceptual Model Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

29. Neural Networks VRC cross-section within Rauðhólar, Iceland Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Volcanic Rootless Cones (VRCs)

30. Neural Networks VRC cross-section within Rauðhólar, Iceland Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Volcanic Rootless Cones (VRCs)

31. Neural Networks VRC cross-section within Rauðhólar, Iceland Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Volcanic Rootless Cones (VRCs)

32. Neural Networks VRC cross-section within Rauðhólar, Iceland Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Volcanic Rootless Cones (VRCs)

33. Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Volcanic Rootless Cones (VRCs)

34. 1 km Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions VRC analogs among the western Tartarus Colles cone groups, Mars Volcanic Rootless Cones (VRCs)

35. 1 km Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Volcanic Rootless Cones (VRCs) VRC analogs among the eastern Tartarus Colles cone groups, Mars

36. Mars Exploration Rover Spirit images of volcanic rocks in Gusev Crater, Mars Volcano–H 2 O Interactions on Mars Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

37. Mars Exploration Rover Spirit images of volcanic rocks in Gusev Crater, Mars Volcano–H 2 O Interactions on Mars Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

38. Mars Exploration Rover Spirit images of volcanic rocks in Gusev Crater, Mars Volcano–H 2 O Interactions on Mars Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

40. Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Earth

41. Terrestrial Analog: Laki, Iceland Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions N

42. Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions N Terrestrial Analog: Laki, Iceland

43. 1070ºC 564 570 568 566 Elevation (m) Rootless Cone Archetypes Brittle Crust Viscous Layer Molten Core Saturated Unsaturated Lava Flow Sediments 800ºC Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions 150 m

44. 564 570 568 566 Elevation (m) Rootless Cone Archetypes Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions 150 m

45. 564 570 568 566 Elevation (m) Rootless Cone Archetypes Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions 150 m

46. 564 570 568 566 Elevation (m) Rootless Cone Archetypes Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions 150 m

47. 564 570 568 566 Elevation (m) Rootless Cone Archetypes Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions 150 m

48. 564 570 568 566 Elevation (m) Rootless Cone Archetypes Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions 150 m

49. 564 570 568 566 Elevation (m) Geospatial Analysis Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions 150 m

50. 564 570 568 566 Elevation (m) Geospatial Analysis Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions 150 m

51. 564 570 568 566 Elevation (m) Geospatial Analysis Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Hekla 1104 pumice layer 150 m

52. 564 570 568 566 Elevation (m) Geospatial Analysis Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions 150 m

53. Kipuka Mantled Terrain Lava Rootless Cone Crater Crater Floor Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Geospatial Analysis 1000 m

54. Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Geospatial Analysis

55. ○ R a : mean actual distance between Nearest Neighbor (NN) pairs R e : mean expected distance between NNs Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Geospatial Analysis if R < 1 then clustered if R ≈ 1 then random if R > 1 then repelled

56. R : 1.00 | c |: 0.05 R : 1.91 | c |: 6.64 R : 0.47 | c |: 7.13 Clustered Poisson (Random) Evenly Spaced x R < 1 R = 1 R > 1 Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Geospatial Analysis Figure adapted from Bruno et al. (2006)

57. Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Geospatial Analysis

58. Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Geospatial Analysis Population size (N) Repelled Clustered

59. Discharge from extraction well Maximum radius of influence Distance from extraction well Aquifer thickness Water saturated depth at r Water table draw down at r Q R r H h S Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Geospatial Analysis

60. Discharge from extraction well Maximum radius of influence Distance from extraction well Aquifer thickness Water saturated depth at r Water table draw down at r Q R r H h S Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Geospatial Analysis

61. Discharge from extraction well Maximum radius of influence Distance from extraction well Aquifer thickness Water saturated depth at r Water table draw down at r Q R r H h S Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Geospatial Analysis

63. Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Mars

64. Tartarus Colles Cone Groups, Mars MOLA Digital Terrain Model of Elysium Planitia, Mars 1000 km 9 km -9 km 0 km Elevation Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

65. 9 km -9 km 0 km Elevation 1000 km Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Tartarus Colles Cone Groups, Mars

66. Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Tartarus Colles Cone Groups, Mars Cerberus Fossae 3 unit Late Amazonian Cerberus Fossae 2 unit Late to Middle Amazonian Elysium Rise unit Early Amazonian to Early Hesperian Crater unit Late Amazonian to Early Hesperian Arcadia Planitia unit Late to Early Hesperian Nepenthes Mensae unit Early Hesperian to Early Noachian Noachian Hesperian Amazonian 3.5 1.8 0 Billions of years before present

67. Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Tartarus Colles Cone Groups, Mars Elysium Rise unit Early Amazonian to Early Hesperian Nepenthes Mensae unit Early Hesperian to Early Noachian VRC-hosting Tartarus Colles lava Shield-like Tartarus Colles lava Elevation (m) Noachian Hesperian Amazonian 3.5 1.8 0 Billions of years before present

68. Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Tartarus Colles Cone Groups, Mars Elysium Rise unit Early Amazonian to Early Hesperian Nepenthes Mensae unit Early Hesperian to Early Noachian VRC-hosting Tartarus Colles lava Shield-like Tartarus Colles lava VRCs Elevation (m) Noachian Hesperian Amazonian 3.5 1.8 0 Billions of years before present

69. Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Tartarus Colles Cone Groups, Mars Elysium Rise unit Early Amazonian to Early Hesperian Nepenthes Mensae unit Early Hesperian to Early Noachian VRC-hosting Tartarus Colles lava Shield-like Tartarus Colles lava VRCs Elevation (m) Noachian Hesperian Amazonian 3.5 1.8 0 Billions of years before present

70. Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Tartarus Colles Cone Groups, Mars Elysium Rise unit Early Amazonian to Early Hesperian Nepenthes Mensae unit Early Hesperian to Early Noachian VRC-hosting Tartarus Colles lava Shield-like Tartarus Colles lava VRCs Elevation (m) Pitted terrain Noachian Hesperian Amazonian 3.5 1.8 0 Billions of years before present

71. Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Tartarus Colles Cone Groups, Mars Elysium Rise unit Early Amazonian to Early Hesperian VRC-hosting Tartarus Colles lava Late to Middle Amazonian (75–250 Ma)

72. (log N i ) Nearest Neighbor (NN) Results Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Repelled Clustered

73. Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Nearest Neighbor (NN) Results Repelled Clustered

74. Nearest Neighbor (NN) Results Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Repelled Clustered

75. (log N i ) Nearest Neighbor (NN) Results Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Repelled Clustered

76. Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Nearest Neighbor (NN) Results Lava Thickness N 10 km

77. Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Nearest Neighbor (NN) Results Lava Thickness N 10 km

78. Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Nearest Neighbor (NN) Results Lava Thickness N 10 km

79. Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Nearest Neighbor (NN) Results 3 km Lava Thickness N 10 km

80. 3 km 3 km Lava Thickness Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions N 10 km Nearest Neighbor (NN) Results

81. Thermodynamic Model Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

82. Thermodynamic Model Differences in isotherm depths on Mars and the Earth Mars (T A = 210 K) Earth (T A = 270 K) Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

83. Thermodynamic Model Hydrothermal system longevity (substrate temperature >273 K) Mars (T A = 210 K) Earth (T A = 270 K) Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

84. Thermodynamic Model X Y X Y Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions X Y

85. Thermodynamic Model Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions X Y X Y X Y X Y

86. Thermodynamic Model 273 K at T L = 1273 K Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions X Y X Y X Y X Y

87. Thermodynamic Model 273 K at T L = 1273 K Maximum 273 K Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions X Y X Y X Y X Y

88. Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Discussion

89. Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Summary

90. Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Summary

91. Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Summary

92. Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Summary

93. Summary Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

94. Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions Summary Minimum H 2 O volume = (VRC domain area) × (Isotherm depth at T L = 1273 K) × (Substrate porosity) Minimum H 2 O volume = (2014 km 2 ) x (21 to 42 m for 30 to 60 m-thick lava) × (0.1 to 0.3) Minimum H 2 O volume = ~3.7 to 22.5 km 3

95. Summary Minimum H 2 O volume = (VRC domain area) × (Isotherm depth at T L = 1273 K) × (Substrate porosity) Minimum H 2 O volume = (2014 km 2 ) x (21 to 42 m for 30 to 60 m-thick lava) × (0.1 to 0.3) Minimum H 2 O volume = ~3.7 to 22.5 km 3 Paleo-climate = intermediate obliquity (~35°) 75–250 Ma ago, with excursions to ~25–32° Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

96. Summary Minimum H 2 O volume = (VRC domain area) × (Isotherm depth at T L = 1273 K) × (Substrate porosity) Minimum H 2 O volume = (2014 km 2 ) x (21 to 42 m for 30 to 60 m-thick lava) × (0.1 to 0.3) Minimum H 2 O volume = ~3.7 to 22.5 km 3 Paleo-climate = intermediate obliquity (~35°) 75–250 Ma ago, with excursions to ~25–32° Hydrothermal system longevity = up to ~1300 years for 75 m-thick lava and T A = 210 K Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

97. Conclusions Introduction Methods Results Discussion Conclusions Introduction Earth Mars Discussion Conclusions

101. DGPS Mapping Introduction Methods Results Discussion Conclusions

102. Terrestrial Analogue: Laki, Iceland Introduction Methods Results Discussion Conclusions N

103. Terrestrial Analogue: Laki, Iceland Introduction Methods Results Discussion Conclusions

104. Kipuka Mantled Terrain Lava Rootless Cone Crater Crater Floor Facies Mapping Introduction Methods Results Discussion Conclusions 1000 m

105. Introduction Methods Results Discussion Conclusions Facies Mapping Differential GPS tracks define facies boundaries 15 m

106. Introduction Methods Results Discussion Conclusions Facies Mapping DGPS boundaries were digitized in ArcGIS 15 m

107. Introduction Methods Results Discussion Conclusions Facies Mapping DGPS boundaries were digitized in ArcGIS 15 m

108. 2216 rootless eruptions sites defined using Differential GPS 86 stratigraphic sections used to constrain kipuka locations and emplacement chronology On Wednesday, August 20, 2008 this geological map was used to prevent renewed quarrying of the Laki rootless cones Introduction Methods Results Discussion Conclusions Facies Mapping

109. 0.5 m 1.0 m Katla 1918 Laki (S2) Emplacement Chronology Laki S1a Layer (Fissures 1) June 8, 1783 Laki S1b Layer (Fissures 2) June 10-11, 1783 Laki S2 Layer (Fissure 3) June 14, 1783 Introduction Methods Results Discussion Conclusions

110. 0.5 m Katla 1918 Laki (S2) Emplacement Chronology 1.0 m Laki S1a Layer (Fissures 1) June 8, 1783 Laki S1b Layer (Fissures 2) June 10-11, 1783 Laki S2 Layer (Fissure 3) June 14, 1783 Introduction Methods Results Discussion Conclusions

111. 0.5 m Katla 1918 Laki (S1 + S2) Katla 1755 Katla 1625 Emplacement Chronology 1.0 m Laki S1a Layer (Fissures 1) June 8, 1783 Laki S1b Layer (Fissures 2) June 10-11, 1783 Laki S2 Layer (Fissure 3) June 14, 1783 Introduction Methods Results Discussion Conclusions

112. Emplacement Chronology Introduction Methods Results Discussion Conclusions

113. Nearest Neighbor (NN) Analysis Introduction Methods Results Discussion Conclusions

114. ○ R a : mean actual distance between Nearest Neighbor (NN) pairs R e : mean expected distance between NNs c: test statistic for measuring the significance of R σ : standard error of the mean expected NN distance R e Introduction Methods Results Discussion Conclusions Geospatial Analysis

115. Introduction Methods Results Discussion Conclusions Geospatial Analysis Population size (N)

116. Introduction Methods Results Discussion Conclusions Geospatial Analysis Population size (N)

117. Thermodynamic Modeling Introduction Methods Results Discussion Conclusions

118. Thermodynamic Model T = temperature at time t in seconds T L = temperature of the lava (initially equal to T M ) T B = temperature at the base of the flow (initially equal to T M ) T M = temperature of basaltic magma (1450 or 1617 K) d = depth beneath the top of the flow in meters k = thermal diffusivity (7 × 10 -7 m 2 s -1 ) Other boundary conditions and considerations: 1. Upper flow surface of the lava is kept at ambient temperature ( T A ) 2. Substrate temperature is initially set to T A 3. k adjusted to account for the heat absorbed in melting and vaporizing H 2 O Analytical model: Introduction Methods Results Discussion Conclusions

119. Thermodynamic Model Introduction Methods Results Discussion Conclusions Effects of ambient temperature (T A ) on isotherm depth Mars (T A = 210 K) Earth (T A = 270 K)

120. Thermodynamic Model Introduction Methods Results Discussion Conclusions

121. Obliquity-Driven Climate Change Introduction Methods Results Discussion Conclusions

122. Obliquity-Driven Climate Change Introduction Methods Results Discussion Conclusions Probabilistic obliquity scenarios for Mars during the past 250 Ma (Laskar et al. , 2004) Obliquity (Axial Tilt) Plane of the ecliptic If ice then obliquity >25° If desiccation then obliquity <32°