Basin Groups

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Basin Groups refers to 9 subdivisions of the lunar Pre-Nectarian geologic period. It is the second era of the Hadean.

Definition

The motivation for creating the Basin Groups subdivisions was to place 30 pre-Nectarian impact basins into 9 relative age groups. The relative age of the first basin in each group is based on crater densities and superposition relationships, whereas the other basins are included based on weaker grounds.[1] Basin Group 1 has no official age for its base, and the boundary between Basin Group 9 and the Nectarian period is defined by the formation of the Nectaris impact basin.

The age of the Nectaris basin is somewhat contentious, with the most frequently cited numbers placing it at 3.92 Ga, or more infrequently at 3.85 Ga.

Cryptic era together make up the totality of the Pre-Nectarian
period.

Early ImbrianLate ImbrianPre-NectarianNectarianEratosthenianCopernican period
Millions of years before present


Relationship to Earth's geologic time scale

Since little or no

RNA world hypothesis) may have evolved on earth around 4 bya
during this era.

See also

References

  1. ^ Don Wilhelms (1987). Geologic History of the Moon. U.S. Geological Survey Professional Paper 1348.
  2. S2CID 117660264
    .
  3. ^ R. Korotev; J. Gillis; L. Haskin & B. Jolliff (2002). "On the age of the Nectaris basin". Workshop on Moon Beyond: abstract 3029.
  4. ^ 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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