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Mairan (crater)

Coordinates: 41°36′N 43°24′W / 41.6°N 43.4°W / 41.6; -43.4
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Coordinates41°36′N 43°24′W / 41.6°N 43.4°W / 41.6; -43.4
Diameter40 km
Depth3.4 km
Colongitude44° at sunrise
EponymJean J. d'Ortous
de Mairan
Mairan area (top) in selenochromatic format holding some normal (yellow)/pyroclastic(red) selenochromatic landmarks
Oblique view from Apollo 15

Mairan is a lunar impact crater that is located on a highland peninsula between Oceanus Procellarum to the west and Mare Imbrium to the east. To the north-northeast is the comparably sized crater Sharp. Northwest of Mairan is the heavily eroded Louville.

The outer rim of Mairan has not been significantly eroded or impacted, and retains a sharp edge. The surface around Mairan is rough and irregular, with a multitude of many tiny craters, particularly to the south and west. The inner walls display some terracing, and flow down to a relatively flat interior floor.

Mairan is a crater of Upper (Late) Imbrian age.[1]

Mairan domes[edit]

The volcanic complex, known as Mairan Hills or Mairan Domes, is composed of Mairan T together with three satellite domes (Mairan Northwest, Mairan Middle, and Mairan South). It was formed by two volcanic episodes 3.75±0.1 and 3.35±0.2 billion years ago, extruding a viscous silicic lava simultaneously with basalt eruptions in nearby mare. Most of volcanic complex, except for dome summits, is now buried under mare surface.[2]

In the mare, due west of Mairan, is a small lunar dome designated Mairan T with 3.8 km wide depression at the summit (in official IAU nomenclature "Mairan T" name refers only to the depression), believed to be a caldera[3] The width of hill is about 7 km, and height is about 800 m.[4] It is one of four unusually steep (with slopes reaching 22-27 degrees) and bright domes in area which are thought to be formed by very viscous, high-Si lava.[5]

The composition of domes is changing from the north to south, with Mairan Northwest composed of pyroxenes with 30% quartz admixture, while Mairan South dome composed of nearly pure quartz, with extremely high thorium concentration of 83±19 ppm.[6]

Rima Mairan[edit]

There is a sinuous rille along the southwest edge of the highland peninsula containing Mairan. It is designated Rima Mairan, and follows a north–south course for a length of about 100 kilometers.

Oblique view of part of Rima Mairan, from Apollo 15

Satellite craters[edit]

By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Mairan.

Mairan Latitude Longitude Diameter
A 38.6° N 38.8° W 16 km
C 38.6° N 46.0° W 7 km
D 40.9° N 45.4° W 10 km
E 37.8° N 37.2° W 6 km
F 40.3° N 45.1° W 9 km
G 40.9° N 50.8° W 6 km
H 39.3° N 40.0° W 5 km
K 40.8° N 41.0° W 6 km
L 39.0° N 43.2° W 6 km
N 39.2° N 45.5° W 6 km
T 41.7° N 48.3° W 3 km
Y 42.7° N 44.0° W 7 km


  1. ^ The geologic history of the Moon. USGS Professional Paper 1348. By Don E. Wilhelms, John F. McCauley, and Newell J. Trask. U.S. Government Printing Office, Washington: 1987. Table 11.2.
  2. ^ Geology of Mairan middle dome: Its implication to silicic volcanism on the Moon
  3. ^ "Mairan". Gazetteer of Planetary Nomenclature. USGS Astrogeology Research Program.
  4. ^ Tran, T.; Robinson, M. S.; Lawrence, S. J.; Braden, S. E.; Plescia, J.; Hawke, B. R.; et al. (March 2011). "Morphometry of Lunar Volcanic Domes from LROC" (PDF). 42nd Lunar and Planetary Science Conference, Held March 7–11, 2011 at the Woodlands, Texas. LPI Contribution (1608 p.2228): 2228. Bibcode:2011LPI....42.2228T.
  5. ^ Lena R.; Wöhler C.; Phillips J.; Chiocchetta M. T. (2013). Lunar Domes: Properties and Formation Processes. Springer Science & Business Media. pp. vii, 5–13, 35, 42. Bibcode:2013ldpf.book.....L. doi:10.1007/978-88-470-2637-7. ISBN 9788847026377.
  6. ^ The Mairan domes: Silicic volcanic constructs on the Moon