The pre-Nectarian period of the lunar geologic timescale runs from 4.533 billion years ago (the time of the initial formation of the Moon) to 3.920 billion years ago, when the Nectaris Basin was formed by a large impact. It is followed by the Nectarian period.
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.
Millions of years before present
Impact basinsedit
Lunar impact basins as categorized by Wilhelms et al. (1987)[4]
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 scaleedit
Since little or no geological evidence on Earth exists from the time spanned by the pre-Nectarian period of the Moon, the pre-Nectarian has been used as a guide by at least one notable scientific work[5] to subdivide the unofficial terrestrial Hadeaneon. In particular, it is sometimes found that the Hadean eon is subdivided into the Cryptic era, Basin Groups 1-9, Nectarian and Lower Imbrian, though the first two of these lunar divisions are informal and collectively make up the pre-Nectarian.
^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.
^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
^Don Wilhelms (1987). Geologic History of the Moon. U.S. Geological Survey Professional Paper 1348.
^ Wilhelms, Don; McCauley, John; Trask, Newell (1987). The geologic history of the Moon. Professional Paper. US Geological Survey. p. 148. doi:10.3133/pp1348.
^W. Harland; R. Armstrong; A. Cox; L. Craig; A. Smith; D. Smith (1990). A Geologic time scale 1989. Cambridge University Press.
nectarian, nectarian, period, lunar, geologic, timescale, runs, from, billion, years, time, initial, formation, moon, billion, years, when, nectaris, basin, formed, large, impact, followed, nectarian, period, 4533, 3920, pren, cchronology, 4500, 4000, 3500, 30. The pre Nectarian period of the lunar geologic timescale runs from 4 533 billion years ago the time of the initial formation of the Moon to 3 920 billion years ago when the Nectaris Basin was formed by a large impact It is followed by the Nectarian period Pre Nectarian4533 3920 Ma PreN I N E CChronology 4500 4000 3500 3000 2500 2000 1500 1000 500 0 Pre NectarianNectarianImbrianEratosthenianCopernicanLateEarly Periods on the Lunar Geologic Timescale Axis scale Millions of years ago Usage informationCelestial bodyEarth s MoonTime scale s usedLunar Geologic TimescaleDefinitionChronological unitPeriod Contents 1 Description 2 Impact basins 3 Relationship to Earth s geologic time scale 4 See also 5 References 6 External linksDescription editPre 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 Millions of years before presentImpact basins editLunar impact basinsas categorized by Wilhelms et al 1987 4 Basin name Diameter Age group km nr Procellarum 3 200 1South Pole Aitken 2 500Tsiolkovskiy Stark 700 2Grissom White 600Insularum 600Marginis 580Flamsteed Billy 570Balmer Kapteyn 550Werner Airy 500Pingre Hausen 300Al Khwarizmi King 590Fecunditatis 990 3Australe 880Tranquillitatis 800Mutus Vlacq 700Nubium 690Lomonosov Fleming 620 Basin name Diameter Age group km nr Ingenii 650 4Poincare 340Keeler Heaviside 780Coulomb Sarton 530 5Smythii 840Lorentz 360 6Arnundsen Ganswindt 355 7Schiller Zucchius 325Planck 325Birkhoff 330Freundlich Sharonov 600 8Grimaldi 430 9Apollo 505For 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 editSince little or no geological evidence on Earth exists from the time spanned by the pre Nectarian period of the Moon the pre Nectarian has been used as a guide by at least one notable scientific work 5 to subdivide the unofficial terrestrial Hadean eon In particular it is sometimes found that the Hadean eon is subdivided into the Cryptic era Basin Groups 1 9 Nectarian and Lower Imbrian though the first two of these lunar divisions are informal and collectively make up the pre Nectarian See also editHadean eon related topicsReferences edit 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 Fritz J Bitsch B Kuhrt E Morbidelli A Tornow C Wunnemann 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 Don Wilhelms 1987 Geologic History of the Moon U S Geological Survey Professional Paper 1348 Wilhelms Don McCauley John Trask Newell 1987 The geologic history of the Moon Professional Paper US Geological Survey p 148 doi 10 3133 pp1348 W Harland R Armstrong A Cox L Craig A Smith D Smith 1990 A Geologic time scale 1989 Cambridge University Press External links editPalaeos org Hadean eon Archived 2016 07 28 at the Wayback Machine Retrieved from https en wikipedia org w index php title Pre Nectarian amp oldid 1198524310, wikipedia, wiki, book, books, library,
