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Mercury’s Plains and Volcanism

Mercury’s Plains and Volcanism. Jake Turner PTYS 395. Overview . What are plains? What types of plains does Mercury have? Origins of the plains? Volcanism? How will MESSENGER help?. What are Plains?. F lat or smoothly undulating surfaces

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Mercury’s Plains and Volcanism

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  1. Mercury’s Plains and Volcanism Jake Turner PTYS 395

  2. Overview • What are plains? • What types of plains does Mercury have? • Origins of the plains? • Volcanism? • How will MESSENGER help?

  3. What are Plains? • Flat or smoothly undulating surfaces • They are a canvas on which other landforms devolve. • Plains are evidence for resurfacing or the creation of a smooth surface from a rough surface

  4. Plains on Mercury • About 60% of Mercury is believed to be plains. • Most abundant terrain on Mercury • More widespread and higher albedo than plains on the moon.

  5. Types of Plains • Intercrater • Heavily cratered • Older then smooth • 45% of surface is covered by intercrater plains. • Smooth Plains • Occur in the highlands between clusters of craters. • Young • Confined to interior and exterior of impact basins and large craters. • 15% of surface

  6. Examples of Intercrater Plains

  7. Examples of Smooth Plains

  8. Intercrater Plains • Located between and around clusters of large craters in the heavily cratered highlands. • Age around the period of the heavy bombardment. • 4-4.2 billion years old • Volume of plains decreased as age decreased • Craters less then 50km may have been destroyed by the intercrater plains formation.

  9. Smooth Plains • Two large concentrations • Caloris Basin • Borealis Basin • 90% are associated with older large impact basins • Similar to lunar Maria • Age- 3.8 billions years • End of heavy bombardment

  10. Origins of the Plains 1. Impact Crater Ejecta deposits from large basins • Consists of two parts • A continuous ejecta blanket • Discontinues ejecta beyond the continuous ejecta. 2. Volcanic deposits

  11. Origins of the Smooth Plains Impact Ejecta Theory • Smooth plains around the Caloris basin would be smooth ejecta deposits. • Interior smooth plains would be impact melt. • Other plains would be impact eject or impact melt. • Problem with Impact Ejecta • Cannot explain why the plains cover 15% of the surface compared to 5% on the moon.

  12. Problems with the Impact Ejecta Theory • Cannot explain why the plains cover 15% of the surface compared to 5% on the moon. • For example, Smooth plains around Caloris basin extend 2000km. • No such extensive eject deposits exist on the moon. • Mercury has higher surface gravity then moon.

  13. Smooth PlainsVolcanism • Smooth plains are younger than the basins they occupy or surround. • Embayments are a common feature of lava flows • Isn’t definitive though, still need composition.

  14. Smooth Plain Volcanism • Earth based radar observations show that the annulus of smooth plains surrounding Caloris is like the Lunar Maria. • Color images of Tolstoj basin suggest different composition. A Tolstoj Basin

  15. Intercrater PlainsVolcanic • Covers 45% of the surface • No evidence of source basins • The frequency of the interior morphologies of craters on the intercrater plains is the same as the lunar Maria.

  16. Volcanic Intercrater Plains • Recalibrated data from Mariner 10 suggest that plains have different composition, age, and grain size than the surroundings.

  17. Problems with Volcanism • Because of Mariner 10’s bad lighting and resolution conditions volcanic landforms are difficult to find. • Composition not know exactly

  18. How Messenger will help? • Better resolution • Experience with lighting conditions • Analyze composition more thoroughly and fully • Early data analysis might suggest relatively recent volcanism.

  19. Biblography • R.G. StroR.G. Strom, A.L. Sprague, Exploring Mercury: The Iron Planet (Springer, New York, 2003) • Kiefer, Walter and Murray, Brue. Formation of Mercury’s Smooth Plains. Pasadena, California. 1987. • G. Jeffrey Taylor. Mercury Unveiled, Hawaii’s Institute of Geophysics and Planetology, University of Hawaii. http://solarsystem.nasa.gov/scitech/display.cfm?T_ID=365

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