Amazonian (Mars)

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This article is about the Mars geologic system and time period. For other senses, see Amazonia.
Amazonian
2000 – 0 Ma (lower bound uncertain – between about 3200 and 2000 million years ago)
Period
Stratigraphic unitSystem
Type sectionAmazonis Planitia

The Amazonian is a

time period on the planet Mars characterized by low rates of meteorite and asteroid impacts and by cold, hyperarid conditions broadly similar to those on Mars today.[1][2] The transition from the preceding Hesperian period is somewhat poorly defined. The Amazonian is thought to have begun around 3 billion years ago, although error bars on this date are extremely large (~500 million years).[3]
The period is sometimes subdivided into the Early, Middle, and Late Amazonian. The Amazonian continues to the present day.

The Amazonian period has been dominated by impact crater formation and Aeolian processes with ongoing isolated volcanism occurring in the Tharsis region and Cerberus Fossae, including signs of activity as recently as a tens of thousands of years ago in the latter[4] and within the past few million years on Olympus Mons, implying they may still be active but dormant in the present.[5]

Description and name origin

The Amazonian System and Period is named after Amazonis Planitia, which has a sparse crater density over a wide area. Such densities are representative of many Amazonian-aged surfaces. The type area of the Amazonian System is in the Amazonis quadrangle (MC-8) around 15°N 158°W / 15°N 158°W / 15; -158.

Pre-NoachianNoachianHesperianPost-HesperianAmazonian (Mars)
Martian Time Periods (Millions of Years Ago)

Amazonian chronology and stratigraphy

HiRISE image illustrating superpositioning, a principle that lets geologists determine the relative ages of surface units. The dark-toned lava flow overlies (is younger than) the light-toned, more heavily cratered terrain (older lava flow?) at right. The ejecta of the crater at center overlies both units, indicating that the crater is the youngest feature in the image.

Because it is the youngest of the Martian periods, the chronology of the Amazonian is comparatively well understood through traditional geological laws of superposition coupled to the relative dating technique of crater counting. The scarcity of craters characteristic of the Amazonian also means that unlike the older periods, fine scale (<100 m) surface features are preserved.[6] This enables detailed, process-orientated study of many Amazonian-age surface features of Mars as the necessary details of form of the surface are still visible.

Furthermore, the relative youth of this period means that over the past few hundred million years it remains possible to reconstruct the statistics of the orbital mechanics of the

Milankovich cycles
.

Together, these features – good preservation, and an understanding of the imposed solar flux – mean that much research on the Amazonian of Mars has focussed on understanding its climate, and the surface processes that respond to the climate. This has included:

Good preservation has also enabled detailed studies of other geological processes on Amazonian Mars, notably

volcanic processes,[21][22][23] brittle tectonics,[24][25] and cratering processes.[26][27][28]

System vs. Period

e  h
Segments of rock (strata) in chronostratigraphy Periods of time in geochronology Notes (Mars)
Eonothem
Eon
 not used for Mars
Erathem
Era
 not used for Mars
System
Period
 3 total; 108 to 109 years in length
Series
Epoch
 8 total; 107 to 108 years in length
Stage
Age
 not used for Mars
Chronozone
Chron
 smaller than an age/stage; not used by the ICS timescale

System and Period are not interchangeable terms in formal stratigraphic nomenclature, although they are frequently confused in popular literature. A system is an idealized stratigraphic

index fossils) that indicate dramatic (often abrupt) changes in the dominant fauna or environmental conditions. (See Cretaceous–Paleogene boundary
as example.)

At any location, rock sections in a given system are apt to contain gaps (

absolute ages on Mars are determined by impact crater density, which is heavily dependent upon models of crater formation over time.[31] Accordingly, the beginning and end dates for Martian periods are uncertain, especially for the Hesperian/Amazonian boundary, which may be in error by a factor of 2 or 3.[32][33]

Images

  • Pedestal crater in Amazonis with Dark Slope Streaks, as seen by HiRISE.
    Pedestal crater in Amazonis with Dark Slope Streaks, as seen by HiRISE.
  • Wall of Tooting Crater, as seen by HiRISE.
    Wall of
    Tooting Crater
    , as seen by HiRISE.
  • Pettit Crater rim, as seen by HiRISE.
    Pettit Crater
    rim, as seen by HiRISE.
  • Nicholson mound with dark streaks, as seen by HiRISE.
    Nicholson mound
    with dark streaks, as seen by HiRISE.
  • Lycus Sulci, as seen by HiRISE.
    Lycus Sulci, as seen by HiRISE.
  • Streamlined Island in Marte Vallis, as seen by HiRISE.
    Streamlined Island in Marte Vallis, as seen by HiRISE.
  • Tartarus Colles channel, as seen by HiRISE.
    Tartarus Colles channel, as seen by HiRISE.
  • Channels From Fissure, as seen by HiRISE.
    Channels From Fissure, as seen by HiRISE.
  • Narrow ridges, as seen by HiRISE.
    Narrow ridges, as seen by HiRISE.
  • Plateau made up of Medusae Fossae materials and rootless cones, as seen by HiRISE.
    Plateau made up of Medusae Fossae materials and rootless cones, as seen by HiRISE.
  • Surfaces in Amazonis quadrangle, as seen by HiRISE.
    Surfaces in Amazonis quadrangle, as seen by HiRISE.

See also

Notes and references

  1. ^ Tanaka, K.L. (1986). The Stratigraphy of Mars. J. Geophys. Res., Seventeenth Lunar and Planetary Science Conference Part 1, 91(B13), E139–E158.
  2. ^ Carr, M.H. (2006), The Surface of Mars. Cambridge Planetary Science Series, Cambridge University Press.
  3. doi:10.1016/j.icarus.2011.07.024
    .
  4. S2CID 226299879
    .
  5. ^ Martel, Linda M. V. (January 31, 2005). "Recent Activity on Mars: Fire and Ice". Planetary Science Research Discoveries. Retrieved July 11, 2006.
  6. doi:10.1002/jgre.20053
    .
  7. doi:10.1016/j.icarus.2004.04.005
    .
  8. doi:10.1016/j.epsl.2009.08.031
    .
  9. ^ Head, J.W., III, Mustard, J.F., Kreslavsky, M.A., Milliken, R.E., and Marchant, D.R., 2003, Recent ice ages on Mars: Nature, v. 426, p. 797–802.
  10. doi:10.1016/j.icarus.2009.02.018
    .
  11. doi:10.1016/j.icarus.2010.02.021
    .
  12. doi:10.1002/2015JE004891
    .
  13. ^ Leblanc, F., and R. E. Johnson. "Role of molecular species in pickup ion sputtering of the Martian atmosphere." Journal of Geophysical Research: Planets (1991–2012) 107.E2 (2002): 5–1.
  14. doi:10.1006/icar.2002.6921
    .
  15. ^ Kolb, Eric J., and Kenneth L. Tanaka. "Geologic history of the polar regions of Mars based on Mars Global Surveyor data: II. Amazonian Period." Icarus 154.1 (2001): 22–39.
  16. Philip R. Christensen
    , and Timothy N. Titus. "CO2 jets formed by sublimation beneath translucent slab ice in Mars' seasonal south polar ice cap." Nature 442.7104 (2006): 793–796.
  17. ^ Balme, Matt, et al. "Transverse aeolian ridges (TARs) on Mars." Geomorphology 101.4 (2008): 703–720.
  18. ^ Basu, Shabari, Mark I. Richardson, and R. John Wilson. "Simulation of the Martian dust cycle with the GFDL Mars GCM." Journal of Geophysical Research: Planets (1991–2012) 109.E11 (2004).
  19. ^ Read, Peter L., and Stephen R. Lewis. The Martian climate revisited: Atmosphere and environment of a desert planet. Springer Verlag, 2004.
  20. ^ Jakosky, Bruce M., and Roger J. Phillips. "Mars' volatile and climate history." nature 412.6843 (2001): 237–244.
  21. ^ Mangold, N., et al. "A Late Amazonian alteration layer related to local volcanism on Mars." Icarus 207.1 (2010): 265–276.
  22. ^ Hartmann, William K., and Daniel C. Berman. "Elysium Planitia lava flows: Crater count chronology and geological implications." Journal of Geophysical Research: Planets (1991–2012) 105.E6 (2000): 15011–15025.
  23. ^ Neukum, Gerhard, et al. "Recent and episodic volcanic and glacial activity on Mars revealed by the High Resolution Stereo Camera." Nature 432.7020 (2004): 971–979.
  24. ^ Márquez, Álvaro, et al. "New evidence for a volcanically, tectonically, and climatically active Mars." Icarus 172.2 (2004): 573–581.
  25. ^ Mueller, Karl, and Matthew Golombek. "Compressional structures on Mars." Annu. Rev. Earth Planet. Sci. 32 (2004): 435–464.
  26. ^ Robbins, Stuart J., and Brian M. Hynek. "Distant secondary craters from Lyot crater, Mars, and implications for surface ages of planetary bodies." Geophysical Research Letters 38.5 (2011).
  27. ^ Malin, Michael C., et al. "Present-day impact cratering rate and contemporary gully activity on Mars." science 314.5805 (2006): 1573–1577.
  28. ^ Popova, Olga, Ivan Nemtchinov, and William K. Hartmann. "Bolides in the present and past Martian atmosphere and effects on cratering processes." Meteoritics & Planetary Science 38.6 (2003): 905–925.
  29. ^ International Commission on Stratigraphy. "International Stratigraphic Chart" (PDF). Retrieved September 25, 2009.
  30. ^
    ISBN 0-13-390047-9
    .
  31. ^ Masson, P.; Carr, M.H.; Costard, F.; Greeley, R.; Hauber, E.; Jaumann, R. (2001). Geomorphologic Evidence for Liquid Water. Space Science Reviews, 96, p. 352.
  32. ^ Nimmo, F.; Tanaka, K. (2005). Early Crustal Evolution of Mars. Annu. Rev. Earth Planet. Sci., 33, 133–161.
  33. ^ Hartmann, W.K.; Neukum, G. (2001). Cratering Chronology and Evolution of Mars. In Chronology and Evolution of Mars, Kallenbach, R. et al. Eds., Space Science Reviews, 96: 105–164.
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