Pre-Nectarian

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Pre-Nectarian
4533 – 3920 Ma
Chronology

The pre-Nectarian period of the

Nectaris Basin was formed by a large impact. It is followed by the Nectarian
period.

Description

Pre-Nectarian rocks are rare in the lunar sample suite; they are mostly composed of lunar highlands material which have been heavily churned, brecciated, and thermally affected by subsequent impacts, particularly during the Heavy Bombardment Eon[1][2] (HBE; a period of 0.6-1 Gy from the formation of the Moon until at least the formation of the Imbrium Basin ~3.9 Ga, or even later with the formation of Orientale Basin) that marks the approximate beginning of the Nectarian period. The primary pre-Nectarian lunar highland material is dominated by the rock type anorthosite, which suggests that the early stage of lunar crustal formation occurred via mineral crystallization of a global magma ocean.

This geologic period has been informally subdivided into the Cryptic Era (4.533 - 4.172 Ga ago) and Basin Groups 1-9 (4.172 - 3.92 Ga ago),[3] but these divisions are not used on any geologic maps. Similarly the later period has also been called the Aitkenian period.

Early ImbrianLate ImbrianPre-NectarianNectarianEratosthenianCopernican period
Millions of years before present


Impact basins

Lunar impact basins
as categorized by Wilhelms et al. (1987)[4]
Basin name Diameter Age-
group
(km) (nr.)
Procellarum 3,200 1
South Pole-Aitken 2,500
Tsiolkovskiy-Stark 700 2
Grissom-White 600
Insularum 600
Marginis 580
Flamsteed-Billy 570
Balmer-Kapteyn 550
Werner-Airy 500
Pingré-Hausen 300
Al-Khwarizmi / King 590
Fecunditatis 990 3
Australe 880
Tranquillitatis 800
Mutus-Vlacq 700
Nubium 690
Lomonosov-Fleming 620
Basin name Diameter Age-
group
(km) (nr.)
Ingenii 650 4
Poincaré 340
Keeler-Heaviside 780
Coulomb-Sarton 530 5
Smythii 840
Lorentz 360 6
Arnundsen-Ganswindt 355 7
Schiller-Zucchius 325
Planck 325
Birkhoff 330
Freundlich-Sharonov 600 8
Grimaldi 430 9
Apollo 505
For basins with no article, the two prominent
craters' names are separately linked to their
respective articles.
Names of proposed basins are italicized.
 

Relationship to Earth's geologic time scale

Since little or no

Lower Imbrian
, though the first two of these lunar divisions are informal and collectively make up the pre-Nectarian.

See also

References

  1. ^ Fernandes V. A., Fritz J., Weiss B., Garrick-Bethel and Shuster D. (2013) The bombardment history of the Moon as recorded by 40Ar-39Ar chronology. Meteor. and Planet. Sci. 48, 241–269. DOI: 10.1111/maps.12054.
  2. ^ Fritz J., Bitsch B., Kührt E., Morbidelli A., Tornow C., Wünnemann K., Fernandes V.A., Grenfell L.J., Rauer H., Wagner R. and Werner S.C. (2014) Earth-like habitats in planetary systems. Planetary and Space Science 98, 254–267. https://dx.doi.org/ 10.1016/j.pss.2014.03.003i
  3. ^ Don Wilhelms (1987). Geologic History of the Moon. U.S. Geological Survey Professional Paper 1348.
  4. ^ Wilhelms, Don; McCauley, John; Trask, Newell (1987). The geologic history of the Moon. Professional Paper.
    doi:10.3133/pp1348
    .
  5. ^ W. Harland; R. Armstrong; A. Cox; L. Craig; A. Smith; D. Smith (1990). A Geologic time scale 1989. Cambridge University Press.

External links

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