Inter-crater plains on Mercury

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Inter-crater plains on Mercury are a land-form consisting of plains between craters on Mercury.

Santa Maria Rupes
cuts through both the plains and large craters. The scene is 200 km across; north is the top.

Of the eight

Mercury's geology was initially quite limited because observations have only been through the Mariner 10 flyby in 1975 and observations from Earth. The MESSENGER (an acronym of MErcury Surface, Space ENvironment, GEochemistry, and Ranging) mission of 2004 was a robotic NASA spacecraft orbiting the planet, the first spacecraft ever to do so.[1] The data provided by MESSENGER has revealed a geologically complex planet.[2]

Types of plains

Rudaki
. Image taken from the MESSENGER mission. On the floor of Rudaki and the region surrounding the crater to the west, or left, are areas flooded with lava, leaving only the rims of these craters. This terrain is known as smooth plains, formed by volcanic flows on the surface of Mercury. To the east, or right, of this crater are the inter-crater plains which can be present at many different elevations due to previous uplift after formation.

There are two geologically distinct types of plains on Mercury - smooth plains of volcanic origin, and, inter-crater plains, of uncertain origin.[3]

Smooth plains

Smooth plains are widespread flat areas resembling the

Caloris Basin, the largest impact basin on Mercury. However, a noticeable difference between the lunar maria of the Moon and the smooth plains of Mercury is that these smooth plains have the same albedo, or properties, as the bordering inter-crater plains. Even with a lack of volcanic features, it is still believed that smooth plains are of volcanic origin.[3]

Inter-crater plains

Inter-crater plains are the oldest visible surface on Mercury,[3] predating the heavily cratered terrain. They are gently rolling or hilly plains and occur in the regions between larger craters. The inter-crater plains appear to have covered up or destroyed many earlier craters, and show a general scarcity of smaller craters below about 30 km in diameter.[4] It is not clear whether they are of volcanic or impact origin.[4] The inter-crater plains are distributed roughly uniformly over the entire surface of the planet.

Caloris Basin
—Mercury's largest impact crater (left side of image), is surrounded by a ring of mountains with chaotic terrain following this and eventually leading to smooth and inter-crater plains.

The most heavily cratered regions on Mercury contain large areas essentially free of impact craters with diameters greater than 50 kilometers. The surface areas of these regions can basically be divided into two categories: clusters of large craters and plains bordering these clusters of craters. This combination of surface features has been called "inter-crater plains" by the Mariner 10 Imaging Science Team.[5][6] These plains have sparked debate.[7]

Origin hypotheses

An example of inter-crater plains on Mercury. Yellow shows the inter-crater plains, whereas green shows younger impact craters. White is the surrounding areas of these features. Black is other craters of the area.

Unlike smooth plains, the origin of inter-crater plains has yet to be well determined. Research and studies have narrowed the origin of inter-crater plains on Mercury down to two hypotheses. The first hypotheses attributes formation from fluidized impact, ejecta,[8][9] which is the result of a meteorite impacting the surface so hard that it turns to liquid, then liquid debris is ejected into the air and lands, filling in any lower elevation areas or craters. The other hypothesis is that the plains formed from volcanic deposits originating from below the surface of Mercury itself.[10][11]

On the basis of the distribution of inter-crater plains and stratigraphic relationships between secondary craters and smooth plains it is argued that the majority of the inter-crater plains were emplaced volcanically.[12]

MESSENGER data

Information and data were gathered from Mariner 10

Ga (billion years).[13] There is no clear correlation with topography; inter-crater plains cover high-standing plateaus and continue into topographic depressions. These results show that either the formation process must have been able to take place over a range of several kilometers supporting an impact-related origin, or that plains are generally flat lying areas which become uplifted, lowered, or tilted after formation.[14][15]

References

  1. ^ Wall, Mike (March 17, 2011). "NASA spacecraft now circling Mercury - a first". NBC News. Retrieved 18 May 2014.
  2. ^ Lakdawalla, Emily (July 3, 2008). "MESSENGER Scientists 'Astonished' to Find Water in Mercury's Thin Atmosphere". The Planetary Society. Archived from the original on 2016-09-02. Retrieved 2014-05-18.
  3. ^
    Bibcode:2001mses.conf..100S. {{cite book}}: |work= ignored (help)CS1 maint: location missing publisher (link
    )
  4. ^
    Bibcode:2001mses.conf..106W
    .
  5. doi:10.1029/jb080i017p02461
    .
  6. doi:10.1029/JB080i017p02508
    .
  7. ISSN 0094-8276
    .
  8. Bibcode:1974LPSC....5..111O
    .
  9. doi:10.1016/0019-1035(76)90128-7
    .
  10. doi:10.1016/0031-9201(77)90028-0
    .
  11. S2CID 16075828
    .
  12. Bibcode:2014LPI....45.1219W
    .
  13. ^ P. D. Spudis & J. E. Guest (1988). F.Vilas; C. Chapman & M. Matthews (eds.). Stratigraphy and Geologic History of Mercury (PDF). Tucson: University of Arizona Press. pp. 118–164. Archived from the original (PDF) on 2016-03-05. Retrieved 2014-05-16. {{cite book}}: |work= ignored (help)
  14. doi:10.1016/j.icarus.2010.03.009
    .
  15. S2CID 22343038
    .
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