Lunar time scale
| age | period | ≈ age ( mya ) |
|---|---|---|
| Copernican era | 1,000-0 | |
| Eratosthenic age | 3,150-1,000 | |
| Imbrian | Late Imbrian Period | 3,800-3,150 |
| Early Imbrian Period | 3,850-3,800 | |
| Preimbrian | Nectary period | 3,920-3,850 |
| Prenectarian period | 4,600-3,920 | |
The lunar time scale divides the formation of the surface of the moon into six ages or periods, the beginning and end of which are determined by certain events. The absolute dates were obtained with the help of samples of moon material brought by the Apollo astronauts . Based on this dating, further dates could be obtained by counting the frequency of craters.
By superimposing structures on each other, one also obtains relative dates, e.g. B. a smaller crater within a larger crater is obviously younger.
Preimbrian Age
In many of the highlands of the moon, planetologists are currently unable to differentiate between nectaric and prenectaric material, which is why these rocks are often grouped together under the term “pre -imbrian”.
Prenectarian period
The prenectarian period lasted from the formation of the moon to the impact that formed the Mare Nectaris , i.e. from 4,600 to 3,920 million years ago.
Nectary period
The nectary period begins with the Mare Nectaris impact and ends with the impact that formed the Mare Imbrium , so it lasts from about 3,920 to 3,850 million years ago.
Imbrian Age
Early Imbrian Period
The early Imbrian period begins with the impact that created the Mare Imbrium (around 3,850 million years ago) and ends with the creation of the Mare Orientale . The origin of the Mare Orientale is not dated with certainty. A period between 3,840 and 3,720 million years ago is possible.
Late Imbrian Period
The late Imbrian period begins with the emergence of the Mare Orientale and ends with the flooding of the mare basins with molten basalt around 3,150 million years ago.
Eratosthenic age
In the Erathostenic Age, the volcanism of the moon slowly becomes weaker. It is named after the lunar crater Eratosthenes , the formation of which marked the beginning of the era about 3,150 million years ago. At the end of the era about 1,100 million years ago, there is no longer any noteworthy lunar volcanism.
Copernican era
The Copernican Age is the time of the formation of the bright ray craters , of which the Copernicus crater is a striking example. The emergence of Copernicus about 800 mya does not define the beginning of the age. It lasts from about 1,100 million years ago until today. In this age, lunar volcanism has largely come to an end.
Timeline
See also
literature
- Charles J. Byrne: The far side of the moon - a photographic guide. Springer, New York, NY 2008, ISBN 978-0-387-73205-3 , p. 12, Table 3.1 "Estimates of absolute ages of the periods."
- D. Stöffler, G. Ryder: Stratigraphy and isotope ages of lunar geological units: chronological standards for the inner solar system. Space Science Review 96 (2001), pp. 9-54, doi : 10.1023 / A: 1011937020193
- Don Wilhelms: Geologic History of the Moon . US Geological Survey Professional Paper 1348, 1987, online
Web links
- Stratigraphic List of Major Craters and basins (English)
- Lunar Photo of the Day, May 4, 2010 (English)
Individual evidence
- ↑ Stöffler, Ryder: Stratigraphy and isotope ages of lunar geological units. 2001, p. 34