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Sapas Mons, Venus: evolution of a large shield volcano

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Abstract

Magellan radar image data of Sapas Mons, a 600 km diameter volcano located on the flanks of the Arla Rise, permit the distinction of widespread volcanic units on the basis of radar properties, morphology, and spatial and inferred temporal relations, each representing a stage or phase in the evolution of the volcano. Six flow units were identified and are arranged asymmetrically about the volcano. Although there is some evidence for overlapping of units, the stratigraphy clearly indicates a younging upwards sequence. The estimated volume of this 2.4 km high volcano is 3.1 × 104 km3, which is comparable to the largest Hawaiian shield (Mauna Loa, 4.25 × 104 km3), but it is significantly less than an estimated volume for the entire Hawaiian-Emperor chain (1.08 × 106 km3) and less than the lower diameter (100 × 150 km) island of Hawaii (11.3 × 104 km3). Although it is difficult to clearly identify a single lava flow, estimates of apparent single flow volumes range from 4 km3 (for an average unit 5 flow of 3.4 km width, 10 m thickness, and 121 km length) to almost 59 km3 (for a 17.8 km wide, l0 m thick, 330 km long unit 1 flow). Estimates of total volumes for the units show that four of the six flow units have volumes that are within a factor of 1.2 of each other, one unit is approximately three times more voluminous, and the latest unit has a very small volume. Flows within a given unit are very distinct relative to flows in other units with respect to average lengths, aspect ratio, radar brightness, and planimetric outline. There is a weak distinction in rms slope between units and emissivity is correlated with altitude, not unit boundaries. A pair of 25 km diameter scalloped-margin domes occur at the summit and are the source of the last stage of eruptions on Sapas; steep fronts and high aspect ratios suggest that associated flows may have had a high viscosity. Graben form a circumferential structure 75–100 km in diameter surrounding the summit domes and are interpreted to be indicative of subsidence over a central magma reservoir. Radial fractures with associated small edifices cut the lower flanks of the edifice but are not observed within the summit ring of graben; these are interpreted to be the expression of near-surface dykes and may have been emplaced during a period of enhanced activity that correlates with the most voluminous flow unit. Unlike at Hawaii, however, these dykes and small edifices do not seem to be the source of significant flank eruptions. Although some effusive activity may have accompanied their emplacement, the majority of lava flows at Sapas appear to be radial to a single, near-summit point located between the two summit domes.

Calculated effusion rates range from 1.5 × 103 m3/s to 3.1 × 105 m3/s; these values suggest that rates were high compared with the Earth and decreased with time. These rates, and the volumes calculated, give eruption durations for the various units that range from 18 days to over 20 years. If eruption is caused by the influx of magma from depth and rupture of an overpressurized chamber, this suggests a variable flux over the history of the volcano. The late-stage eruptions which formed the summit domes are interpreted to be the result of fractional crystallization and/or volatile build-up in the chamber, following a period of decreased supply from depth.

Local topography and gravity, as well as regional geology support the presence of a mantle plume at Sapas. The similar properties of large volumes of magma over the total history of the volcano, as well as the prolonged period of magma supply and gradual waning, are consistent with a plume origin. These inferences and the observations allow us to characterise the history of the volcano as follows: arrival of the mantle plume caused uplift of topography and surrounding plains formation: continued supply of smaller volumes of material permitted construction of the edifice; development of a magma reservoir (predicted by theory to form at shallow depths) modified eruption characteristics by permitting storage and homogenization of magma; unbuffered conditions prevailed for the majority of eruptions, producing flows of similar volumes but decreasing flow lengths; a period early on of enhanced supply led to buffered chamber conditions, resulting in the eruption of the voluminous flow unit and the emplacement of many lateral dykes; evacuations from the chamber and cooling towards the last stages caused distributed summit collapse and formation of the ring graben; and finally the gradual waning of supply allowed evolution of the magma which produced the late-stage, possibly viscous flows and dome construction. Preliminary observation of Sapas and two other volcanoes at different elevations suggests that altitude-dependent chamber development and growth may influence the complexity of lava flows and determine the existence of collapse calderas. Many features at Sapas are representative of large volcanoes on Venus and thus Sapas Mons is a good example of a typical plume-associated edifice. Sapas differs in many ways from Kilauea, a terrestrial type shield volcano, but these differences can be understood in the context of the Venus environment.

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References

  1. Aubele, J. C., Head, J. W., Crumpler, L. S., Guest, J. E., and Saunders, R. S.: 1992, ‘Fields of Small Volcanoes on Venus (Shield Fields): Characteristics and Implications’,Lun. Planet. Sci. Conf. XXIII, 47–48.

  2. Aubele, J. C. and Slyuta, E. N.: 1990, ‘Small Domes on Venus: Characteristics and Origin’,Earth, Moon, and Planets 50/51, 493–532.

  3. Bargar, K. E. and Jackson, E. D.: 1974, ‘Calculated Volumes of Individual Shield Volcanoes along the Hawaiian-Emperor Chain’,J. of Res., U.S.G.S. 2, 545–550.

  4. Basilevsky, A. T.: 1993, ‘Age of Rifting and Associated Volcanism in Atla Regio, Venus’,Geophys. Res. Let. 20, 883–886.

  5. Best, M. G.: 1982,Igneous and Metamorphic Petrology, W. H. Freeman and Company, New York, 630 pp.

  6. Bindschadler, D. L., Schubert, G., and Kaula, W. M.: 1992, ‘Coldspots and Hotspots: Global Tectonics and Mantle Dynamics of Venus’,J. Geophys. Res. 97, 13,495–13,532.

  7. Blake, S.: 1981, ‘Volcanism and the Dynamics of Open Magma Chambers’,Nature 289, 783–785.

  8. Bruno, B. C., Taylor, G. J., and Lopes-Gautier, R. M. C.: 1993, ‘Quantifying the Effect of Rheology on Plan-View Shapes of Lava Flows’,Lun. Planet. Sci. Conf. XXIV, 207–208.

  9. Bruno, B. C., Taylor, G. J., Rowland, S. K., Lucey, P. G., and Self, S.: 1992, ‘Lava Flows are Fractals’,Geophys. Res. Let. 19, 305–308.

  10. Campbell, B. A.: 1992, ‘Comparison of Magellan Measurements of Surface Roughness on Venus to Topographic Profiles of Terrestrial Basaltic Lava Flows’,Lun. Planet. Sci. Conf. XXIII, 201–202.

  11. Campbell, B. A. and Campbell, D. B.: 1992, ‘Analysis of Volcanic Surface Morphology on Venus from Comparison of Arecibo, Magellan, and Terrestrial Airborne Radar Data’,J. Geophys. Res. 97, 16,293–16,314.

  12. Campbell, D. B., Stacy, N. J. S., Newman, W. I., Arvidson, R. E., Jones, E. M., Musser, G. S., Roper, A. Y., and Schaller, C.: 1992, ‘Magellan Observations of Extended Impact Crater Related Features on the Surface of Venus’,J. Geophys. Res. 97, 16,249–16,277.

  13. Campbell, I. H. and Griffiths, R. W.: 1990, ‘Implications of Mantle Plume Structure for the Evolution of Flood Basalts’,Earth Planet. Sci. Let. 99, 79–93.

  14. Clague, D. A. and Dalrymple, G. B.: ‘The Hawaiian-Emperor Volcanic Chain: Part I, Geologic Evolution’,U.S.G.S. Prof. Paper 1350, 5–54.

  15. Comer, R. E, Solomon, S. C., and Head, J. W.: 1985, ‘Mars: Thickness of the Lithosphere from the Tectonic Response to Volcanic Loads’,Rev. Geophys. 23, 61–92.

  16. Crumpler, L. S. and Aubele, J. C.: 1978, ‘Structural Evolution of Arsia Mons, Pavonis Mons, and Ascreus Mons: Tharsis Region of Mars’,Icarus 34, 496–511.

  17. Davies, G. F.: 1992, ‘Temporal Variation of the Hawaiian Plume Flux’,Earth Planet. Sci. Let. 113, 277–286.

  18. Decker, R. W.: 1987, ‘Dynamics of Hawaiian Volcanoes: An Overview’,U.S.G.S. Prof. Paper 1350, 997–1018.

  19. Dvorak, J. J., Johnson, C., and Tilling, R. I.: 1992, ‘Dynamics of Kilauea Volcano’,Sci. Am. August, 46–53.

  20. Elachi, C., Blom, R., Daily, M., Farr, T., and Saunders, R. S.: 1980, ‘Radar Imaging of Volcanic Fields and Sand Dune Fields: Implications for VOIR’,Radar Geology, An Assessment. Report of the Radar Geology Workshop, Snowmass, Colorado, 513 pp.

  21. Erickson, S. G. and Arkani-Hamed, J.: 1992, ‘Impingement of Mantle Plumes on the Lithosphere: Contrast between Earth and Venus’,Geophys. Res. Lett. 19, 885–888.

  22. Gaddis, L., Mouginis-Mark, R, Singer, R., and Kaupp, V.: 1989, ‘Geologic Analyses of Shuttle Imaging Radar (SIR-B) Data at Kilanea Volcano, Hawaii’,Geolog. Soc. Am. Bull. 101, 317–332.

  23. Griffiths, R. W. and Campbell, I. H.: 1990, ‘Stirring and Structure in Mantle Starting Plumes’,Earth Planet. Sci. Let. 99, 66–78.

  24. Grosfils, E. B. and Head, J. W.: ‘Venusian Stress Directions from Radial Fractures’,Lun. Planet. Sci. Conf. XXIII, 457–458.

  25. Grove, T. L. and Baker, M. B.: 1984, ‘Phase Equilibrium Controls on the Tholeiitic versus Calcalkaline Differentiation Trends’,J. Geophys. Res. 89, 3253–3274.

  26. Guest, J. E., Bulmer, M. H., Aubele, J., Beratan, K., Greeley, R., Head, J. W., Michaels, G., Weitz, C., and Wiles, C.: 1992, ‘Small Volcanic Edifices and Volcanism in the Plains of Venus’,J. Geophys. Res. 97, 15,949–15,966.

  27. Head, J. W.: 1994, ‘Volcano Instability Development: A Planetary Perspective’, submitted toProceedings of the Conference on ‘Volcano Instability on the Earth and Other Planets’, Geological Society of London.

  28. Head, J. W., Campbell, D. B., Elachi, C., Guest, J. E., McKenzie, D. P., Saunders, R. S., Schaber, G. G., and Schubert, G.: 1991, ‘Venus Volcanism: Initial Analysis from Magellan Data’,Science 252, 276–288.

  29. Head, J. W., Crumpler, L. Aubele, J. Guest, J., and Saunders, R. S.: 1992, ‘Venus Volcanism: Classification of Volcanic Features and Structures, Associations, and Global Distribution from Magellan Data’,J. Geophys. Res. 97, 13,153–13,197.

  30. Head, J. W., Magee Roberts, K., Wilson, L., and Pinkerton, H.: 1993, ‘Lava Flow-Field Morphological Classification and Interpretation: Examples from Venus’,Lun. Planet. Sci. Conf. XXIV, 627–628.

  31. Head, J. W. and Wilson, L.: 1986, ‘Volcanic Processes and Landforms on Venus: Theory, Predictions, and Observations’,J. Geophys. Res. 91, 9407–9446.

  32. Head, J. W. and Wilson, L.: 1992, ‘Magma Reservoirs and Neutral Buoyancy Zones on Venus: Implications for the Formation and Evolution of Volcanic Landforms’,J. Geophys. Res. 97, 3877–3903.

  33. Hess, P. C. and Head, J. W.: 1990, ‘Derivation of Primary Magmas and Melting of Crustal Materials on Venus: Some Preliminary Petrogenetic Considerations’,Earth, Moon, and Planets 50/51, 57–80

  34. Hulme, G.: 1974, ‘The Interpretation of Lava Flow Morphology’,Geophys. J. R. Astr. Soc. 39, 361–383.

  35. Kaula, W. M., Bindschadler, D. L., Grimm, R. E., Hansen, V. L., Roberts, K. M., and Smrekar, S. E.: 1992, ‘Styles of Deformation in Ishtar Terra and their Implications’,J. Geophys. Res. 97 16,085–16,120.

  36. Keddie, S. T. and Head, J. W.: 1994, ‘Height and Altitude Distribution of Large Volcanoes on Venus’,Planet Space Sci. in press.

  37. Kilburn, C. R. J.: 1981, ‘Pahoehoe and aa Lavas: a Discussion and Continuation of the Model of Peterson and Tilling’,Jour. Volc. Geotherm. Res. 11,373–382.

  38. Klose, K. B., Wood, J. A., and Hashimoto, A.: 1992, ‘Mineral Equilibria and the High Radar Reflectivity of Venus Mountaintops’,J. Geophys. Res. 97, 16,353–16,369.

  39. Magee Roberts, K., Guest, J. E., Head, J. W., and Lancaster, M. G.: 1992, ‘Mylitta Fluctus, Venus: Rift-Related, Centralized Volcanism and the Emplacement of Large-Volume Flow Units’,J. Geophys. Res. 97, 15,991–16,015.

  40. Malin, M. C.: 1980, ‘Lengths of Hawaiian Lava Flows’,Geology 8, 306–308.

  41. McGovern, P.J. and Solomon, S. C.: 1993, ‘State of Stress, Faulting, and Eruption Characteristics of Large Volcanoes on Mars’,J. Geophys. Res. 98, 23,553–23,580.

  42. Morgan, P. and Phillips, R. J.: 1983, ‘Hot Spot Heat Transfer: Its Application to Venus and Implications to Venus and Earth’,J. Geophys. Res. 88, 8305–8317.

  43. O'Hara, M. J.: 1977, ‘Geochemical Evolution during Fractional Crystallisation of a Periodically Refilled Magma Chamber’,Nature 266, 503–507.

  44. Olson, R: 1990, ‘Hot Spots, Swells and Mantle Plumes’,Magma Transport and Storage, John Wiley and Sons, New York, 33–51.

  45. Parfitt, E. A. and Head, J. W.: 1992, ‘Radial Fracture Systems on Venus: Conditions of Formation’,Lun. Planet. Sci. Conf. XXIII, 1027–1028.

  46. Parfitt, E. A. and Head, J. W.: 1993, ‘Buffered and Unbuffered Dike Emplacement on Earth and Venus: Implications for Magma Reservoir Size, Depth, and Rate of Magma Replenishment’,Earth, Moon, and Planets 61, 249–281.

  47. Parfitt, E. A., Wilson, L., and Head, J. W.: 1993, ‘Factors Controlling the Rupture Characteristics and Evolution of Basaltic Magma Reservoirs’,J. Volc. Geotherm. Res. 55, 1–14.

  48. Peterson, D. W. and Tilling, R. I.: 1980, ‘Transition of Basaltic Lava from Pahoehoe to aa, Kilauea Volcano, Hawaii: Field Observations and Key Factors’,Jour. Volc. Geotherm. Res. 7, 271–293.

  49. Pettengill, G. H., Ford, P. G., and Wilt, R. J.: 1992, ‘Venus Surface Radiothermal Emission as Observed by Magellan’,J. Geophys. Res. 97, 13,091–13,102.

  50. Phillips, R.J.: 1993, ‘Gravity Investigations of Venusian Highland Features’,EOS Trans. Am. Geophys. Union 74, 374.

  51. Pinkerton, H. and Wilson, L.: 1994, ‘Factors Controlling the Length of Channel-Fed Lava Flows’,Bull. Volcanol. 56, 108–120.

  52. Porter, S. C.: 1979, ‘Geologic Map of Mauna Kea Volcano, Hawaii’, MC-30.

  53. Roberts, K. and Head, J. W.: 1990, ‘Lakshmi Planum, Venus: Characteristics and Models of Origin’,Earth, Moon, and Planets 50/51, 193–249.

  54. Robinson, C. A. and Wood, J. A.: 1993, ‘Recent Volcanic Activity on Venus: Evidence from Radiothermal Emissivity Measurements’,Icarus 102, 26–39.

  55. Rowland, S. K. and Walker, G. P. L.: 1990, ‘Pahoehoe and aa in Hawaii: Volumetric Flow Rate Controls the Lava Structure’,Bull Volcanol 52, 615–628.

  56. Ryan, M. P.: 1987, ‘Neutral Buoyancy and the Mechanical Evolution of Magmatic Systems’,Magmatic Processes: Physicochemical Principles, Geochem. Soc. Spec. Pub. 1, 259–287.

  57. Ryan, M. P.: 1988, ‘The Mechanics and Three-Dimensional Internal Structure of Active Magmatic Systems: Kilauea Volcano, Hawaii’,J. Geophys. Res. 93, 4213–4248.

  58. Ryan, M. P., Blevins, J. Y. K., Okamura, A. T., and Koyanagi, R. Y.: 1983, ‘Magma Reservoir Subsidence Mechanics: Theoretical Summary and Application to Kilauea Volcano, Hawaii’,J. Geophys. Res. 88, 4147–4181.

  59. Schaber, G. G.: 1991, ‘Volcanism on Venus as Inferred from the Morphometry of Large Shields’,Proc. Lun. Planet. Sci. Conf. XXI 21, 3–11.

  60. Senske, D. A., Schaber, G. G., and Stofan, E. R.: 1992, ‘Regional Topographic Rises on Venus: Geology of Western Eistla Regio and Comparison to Beta Regio and Atla Regio’,J. Geophys. Res. 97, 13,395–13,420.

  61. Smrekar, S. E. and Phillips, R. J.: 1990, ‘Geoid to Topography Ratios for 14 Venusian Features: Implications for Compensation Mechanisms’,Lun. Planet. Sci. Conf. XXI, 1176–1177.

  62. Smrekar, S. E. and Phillips, R. J.: 1991, ‘Venusian Highlands: Geoid to Topography Ratios and their Implications’,Earth Planet. Sci. Let. 107, 582–597.

  63. Solomon, S. C. and Head, J. W.: 1982, ‘Mechanisms for Lithospheric Heat Transport on Venus: Implications for Tectonic Style and Volcanism’,J. Geophys. Res. 87, 9236–9246.

  64. Solomon, S. C., McGovern, P. J., Simons, M., and Head, J. W.: 1993, ‘Gravity Anomalies over Venusian Volcanoes: Implications for Lithospheric Thickness and Volcano History’,EOS Trans. Am. Geophys. Union 74, 375.

  65. Stofan, E. R., Sharpton, V. L., Schubert, G., Baer, G., Bindschadler, D. L., Janes, D. M., and Squyres, S. W.: 1992, ‘Global Distribution and Characteristics of Coronae and Related Features on Venus: Implications for Origin and Relation to Mantle Processes’,J. Geophys. Res. 97, 13,347–13,378.

  66. Tait, S., Jaupart, C., and Vergniolle, S.: 1989, ‘Pressure, Gas Content and Eruption Periodicity of a Shallow, Crystallising Magma Chamber’,Earth Planet. Sci. Let. 92, 107–123.

  67. Taylor, G. J., Bruno, B. C., and Baloga, S.: 1991, ‘Lava Flow Dynamics: Clues from Fractal Properties of Flow Margins’,EOS Trans. Am. Geophys. Union 72, 278.

  68. Tyler, G. L., Ford, P. G., Campbell, D. B., Elachi, C., Pettengill, G. H., and Simpson, R. A.: 1991, ‘Magellan: Electrical and Physical Properties of Venus' Surface’,Science 252, 265–270.

  69. Usselman, T. M. and Hodge, D. S.: 1978, ‘Thermal Control of Low-Pressure Fractionation Processes’,Jour. Volc. Geotherm. Res. 4, 265–281.

  70. Walker, G. P. L.: 1973, ‘Lengths of Lava Flows’,Phil. Trans. R. Soc. Lond. A. 274, 107–118.

  71. Watson, S. and McKenzie, D.: 1991, ‘Melt Generation by Plumes: A Study of Hawaiian Volcanism’,J. of Petrol. 32, 501–537.

  72. Wilson, L. and Head, J. W.: 1988, ‘Nature of Local Magma Storage Zones and Geometry of Conduit Systems below Basaltic Eruption Sites: Pu'u 'O'o, Kilauea East Rift, Hawaii, Example’,J. Geophys. Res. 93, 14,785–14,792.

  73. Wilson, L., Pinkerton, H., Head, J. W., and Magee Roberts, K.: 1993, ‘A Classification Scheme for the Morphology of Lava Flow Fields’,Lun. Planet. Sci. Conf. XXIV, 1527–1528.

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Keddie, S.T., Head, J.W. Sapas Mons, Venus: evolution of a large shield volcano. Earth Moon Planet 65, 129–190 (1994). https://doi.org/10.1007/BF00644896

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Keywords

  • Lava Flow
  • Mantle Plume
  • Flow Unit
  • Effusion Rate
  • Shield Volcano