( mya )
Duration: 300 Ma
Duration: 400 Ma
Duration: 400 Ma
Duration: 400 Ma
The Neo-Archean is a geological age . It represents the last of four eras (Neoarchean = new Archean ) within the geological eon of the Archean . It begins about 2800 million years ago with the end of the Mesoarchean and ends about 2500 million years ago with the beginning of the Paleoproterozoic .
Redefinition of the Neo-Archean
In the course of moving away from period boundaries determined purely by radiometry, the GSSP principle should now be applied as far as possible in the Precambrian, according to Gradstein et al. (2012) . The periods are thus defined on the basis of significant geological events and no longer on arbitrary radiometric ages.
For the Neo-Archaic, Gradstein propose the following new classification:
“The Neo-Archean is divided into the two periods Methanium and Siderium . Methanium begins at 2,780 million years BP with the first appearance of continental flood basalts and a positive d 13 C value in hydrocarbons for the first time . It is followed by the siderium around 2630 million years BP with the first appearance of ribbon ores , which ends around 2420 million years BP with the first paleoproterozoic, glacial deposits . The GSSP for the methanium is at the base of the Mount Roe Basalt of the Fortescue Group ( Mount Bruce Supergroup ) in Western Australia , that of the siderium at the base of the Marra Mamba Iron Formation of the Hamersley Group (also Mount Bruce Supergroup, Western Australia) "
The newly defined Neo-Archean lasts 360 million years; the Mesoarchean-Neoarchean boundary tapers by 20 million years and the Archean-Proterozoan boundary by 80 million years.
Recent research suggests that the prerequisites for the formation of higher mountains were given for the first time in the Neo-Archean . In the ages before that, the continental lithosphere was not yet sufficiently stable for topographical elevations of more than 2,500 meters due to its lower viscosity (high temperature and insufficient thickness) .
A pulse of magmatic activity , the so-called late archaic super event, is unique in the history of the earth . In the period from 2700 to 2500 million years BP it led to enormous crustal growth and probably to the formation of one or more supercontinents ( Kenorland or Superia and Sclavia ). Maxima in the zircon age and in the frequency distribution of greenstone belts and associated orogenic gold deposits underline the importance of this event.
The last period of the Neo-Archean, the Siderium, is characterized by the worldwide formation of ribbon ores . A large part of the iron dissolved in the oceans was thereby precipitated, so that from the Paleoproterozoic the oxygen concentration in the sea water and finally also in the earth's atmosphere could increase (see also Great Oxygen Disaster ).
- 2960 to 2760 million years BP:
- Around 2700 million years BP:
- Between 2530 and 2510 million years BP:
- Around 2500 to 2475 million years ago BP:
- 2473 to 2446 million years BP:
- Around 2400 million years BP:
Significant sedimentary basins and geological formations
- Hamersley Basin with Hamersley Group in Western Australia - 2715 to about 2400 million years BP
- Dharwar Supergroup in the south of India :
- Yellowknife Supergroup in Canada - 2,700 to 2,600 million years BP
- South Pass Greenstone Belt in Wyoming - 2700 to 2600 million years BP
- Ventersdorp Supergroup on the Kaapvaal Craton in South Africa - 2740 to 2690 million years BP
- Transvaal Basin in South Africa - 2670 to 1900 million years BP
- Minas Supergroup in Eastern Brazil - 2610/2580 to 2420 million years BP
- Eastern block of what will later become the North China Craton - 2800 to 2600 million years BP with:
- Taishan Group in western Shandong - 2,767 to 2,671 million years old BP
- Upper Anshan Group in Anshan - 2724 to 2610 million years BP
- In addition, Jiaodong Group in eastern Shandong, Jiapigou Group in southern Jilin , Jianping Group in western Liaoning and Qianxi Group / Zhunhua Group / Dantazi Group / Badaohe Group / Miyun Group in eastern Hebei
Iron (ribbon ores):
- Michipicoten Iron Formation , Canada - 2744 to 2696 million years old BP
- Marra Mamba Iron Formation in Western Australia - 2,630 million years old
- Cauê Banded Iron Formation of the Itabira Group , Minas Supergroup in Brazil - 2580 to 2420 million years BP
- Asbestos Hills subgroup of the Ghaap Group in South Africa - 2,489 to 2,480 million years ago
- Penge formation of the Chuniesport Group in South Africa - around 2,480 million years BP
- Brockman Iron Formation in the Hamersley Basin, Western Australia - 2,469 million years BP
- Kuruman Iron Formation of the Campbellrand Subgroup in South Africa - around 2,465 million years BP
- Witwatersrand Basin , South Africa (multiple deposits) - 3,074 to 2,714 million years BP
- Ventersdorp Contact Reef in South Africa - 2729 ± 19 million years BP
- Eastern Goldfields Province near Kalgoorlie , Yilgarn Craton , Western Australia - 2640 to 2600 million years BP
- Southern Abitibi Greenstone Belt in Canada - <2670 million years BP
- Eastern Dharwar Craton -> 2550 million years BP
- Sukumaland greenstone belt of the Tanzania craton - <2640 million years BP
- Rio das Velhas greenstone belt of the São Francisco craton in Brazil - <2710 million years BP
- Chromium , platinum and palladium :
Baltic shield :
- Formation of the Karelids - 3100 to 2600 million years BP
- Kaapvaal Kraton and Zimbabwe Kraton :
- Superior Kraton :
- East Antarctica :
- Felix M. Gradstein et al .: On the Geologic Time Scale . In: Newsletters on Stratigraphy . tape 45/2 , 2012, p. 171-188 .
- P. Rey, N. Coltitce: Neoarchean lithospheric strengthening and the coupling of Earth's geochemical reservoirs. ( Memento of the original from June 9, 2013 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. In: Geology. Volume 36, 2008, pp. 635-638.
- RW Ojakangas et al: The Talya Conglomerate: an Archean (~ 2.7 Ga) Glaciomarine Formation, Western Dharwar Craton, Southern India . In: Current Science . tape 106 , N ° 3, 2014, p. 387-396 .
- NJ Page: The Precambrian diamictite below the base of the Stillwater Complex, Montana . In: MJ Hambrey, NB Harland (Ed.): Earth's Pre-Pleistocene Glacial Record . Cambridge University Press, Cambridge 1981, pp. 821-823 .
- LM Heaman: 2.45 Ga global mafic magmatism: Earth's oldest superplume? In: Eighth International Conference on Geochronology, Cosmochronology & Isotope Geology, Program with Abstracts, US Geol. Surv. Circular 1107 . Berkeley, California 1994, pp. 132 .