The Chaotian is a proposed time division of the geologic time scale. First proposed in 2010[1] as an eon, it is named after Chaos, the primeval void in Greek mythology. This proposal defines the Chaotian eon as a Solar System-wide time between the initiation of planetary formation and the hypothesised collision of the trojan dwarf planet Theia with the proto-Earth.
| Chaotian | |
|---|---|
| Chronology | |
| Subdivisions | See text |
| Usage information | |
| Celestial body | Earth |
| Regional usage | Proposed subdivision of the Hadean eon |
| Definition | |
| Chronological unit | Era |
| Stratigraphic unit | Erathem |
| First proposed by | C., Zahnle, K. J., Sleep, N. H., and Nisbet, E. G., 2010 |
| Lower boundary definition | Formation of the Earth |
| Upper boundary definition | Collision between Proto-Earth and the Protoplanet Theia |
A revised proposal in 2012[2] suggested the Chaotian as the first era of the Hadean representing the time between the formation of the Solar System c. 4.567 Ga[3] and the oldest preserved crustal material on Earth, a detrital zircon c. 4.404 Ga[4] from the Jack Hills of the Narryer Terrane in Western Australia.
As of September 2023[update], neither proposal had been adopted or officially ratified by the International Union of Geological Sciences.[5]
Subdivisions
The original proposal in 2010 divided the Chaotian into two eras and four periods. No numerical upper age limits were provided, only the younger age limit of ~4.5 Ga for the boundary between the proposed Chaotian and Hadean boundary.
The revised proposal in 2012 did not subdivide the proposed Chaotian era (of the Hadean eon) into periods.
| Eon | Era | Period | Age (Ga) |
|---|---|---|---|
| Chaotian | Neochaotian | Titanomachaen | > ~4.5 |
| Hyperitian | |||
| Eochaotian | Erebrean | ||
| Nephelean |
| Eon | Era | Age (Ga) |
|---|---|---|
| Hadean | Jack Hillsian or Zirconian | 4.404 to 4.030 |
| Chaotian | 4.568 to 4.404 |