Paleoproterozoic
| Paleoproterozoic | ||||||
|---|---|---|---|---|---|---|
stromatolites | ||||||
| Chronology | ||||||
| ||||||
| Proposed redefinition(s) | 2420–541 Ma Gradstein et al., 2012 | |||||
| Proposed subdivisions | Oxygenian Period, 2420–2250 Ma Gradstein et al., 2012 | |||||
| Etymology | ||||||
| Name formality | Formal | |||||
| Alternate spelling(s) | Palaeoproterozoic | |||||
| Usage information | ||||||
| Celestial body | Era | |||||
| Stratigraphic unit | Erathem | |||||
| Time span formality | Formal | |||||
| Lower boundary definition | Defined Chronometrically | |||||
| Lower GSSA ratified | 1991[1] | |||||
| Upper boundary definition | Defined Chronometrically | |||||
| Upper GSSA ratified | 1991[1] | |||||
The Paleoproterozoic Era (eras) of the Proterozoic Eon. The Paleoproterozoic is also the longest era of the Earth's geological history. It was during this era that the continents first stabilized.[clarification needed]
Paleontological evidence suggests that the Earth's rotational rate ~1.8 billion years ago equated to 20-hour days, implying a total of ~450 days per year.[4]
Atmosphere
Before the
enormous increase in atmospheric oxygen, almost all existing lifeforms were anaerobic organisms whose metabolism was based on a form of cellular respiration that did not require oxygen. Free oxygen in large amounts is toxic to most anaerobic organisms. Consequently, most died when the atmospheric free oxygen levels soared in an extinction event called the Great Oxidation Event, which brought atmospheric oxygen levels to up to 10% of their current level.[5] The only creatures that survived were either resistant to the oxidizing and poisonous effects of oxygen or sequestered in oxygen-free environments. The sudden increase of atmospheric free oxygen and the ensuing extinction of the vulnerable lifeforms is widely considered one of the first and most significant mass extinctions on Earth.[6][7]
Emergence of Eukarya
Many crown node
eukaryotes (from which the modern-day eukaryotic lineages would have arisen) have been approximately dated to around the time of the Paleoproterozoic Era.[8][9][10]
While there is some debate as to the exact time at which eukaryotes evolved,[11][12]
current understanding places it somewhere in this era.fossils from the Changcheng Group of North China provide evidence that eukaryotic life was already diverse during the late Palaeoproterozoic.[16]
Geological events
During this era, the earliest global-scale continent-continent collision belts developed. The associated continent and mountain building events are represented by the 2.1–2.0 Ga Trans-Amazonian and
Akitkan Orogen in Siberia; the ~1.95 Ga Khondalite Belt; the ~1.85 Ga Trans-North China Orogen in North China; and the 1.8-1.6 Ga Yavapai and Mazatzal
orogenies in southern North America.
That pattern of collision belts supports the formation of a Proterozoic supercontinent named
Nuna.[17][18] That continental collisions suddenly led to mountain building at large scale is interpreted as having resulted from increased biomass and carbon burial during and after the Great Oxidation Event: Subducted carbonaceous sediments are hypothesized to have lubricated compressive deformation and led to crustal thickening.[19]
Arvidsjaur porphyries.[20]
The lithospheric mantle of Patagonia's oldest blocks formed.[21]
Wikimedia Commons has media related to Paleoproterozoic.
See also
- Boring Billion – Earth history, 1.8 to 0.8 billion years ago
- Suavjärvi impact structure – Lake and claimed impact structure in Karelia, northwest Russia
- Francevillian biota – Possibly earliest multicellular lifeforms
- Vredefort impact structure – Largest verified impact structure on Earth, about 2 billion years old
- Sudbury Basin – Third largest verified astrobleme on earth, remains of an Paleoproterozoic Era impact
- Neoarchean – Fourth era of the Archean Eon
References
- ^ .
- ^ "palaeo-". Lexico UK English Dictionary. Oxford University Press. Archived from the original on 2020-06-18. "Proterozoic". Lexico UK English Dictionary. Oxford University Press. Archived from the original on 2020-06-17.
- ^ "Proterozoic". Merriam-Webster Dictionary.
- S2CID 122908383.
- .
- PMID 31405980.
- ISBN 9780520210646.
- hdl:10037/24808. Retrieved 15 December 2022.
- PMID 11580860.
- PMID 15005799.
- PMID 12060757.
- S2CID 21064445.
- PMID 9435239.
- PMID 10097391.
- .
- S2CID 134362289. Retrieved 29 December 2022.
- .
- .
- ^ John Parnell, Connor Brolly: Increased biomass and carbon burial 2 billion years ago triggered mountain building. Nature Communications Earth & Environment, 2021, doi:10.1038/s43247-021-00313-5 (Open Access).
- ISBN 978-91-7158-960-6.
- .
External links
- EssayWeb Paleoproterozoic Era
- First breath: Earth's billion-year struggle for oxygen New Scientist, #2746, 5 February 2010 by Nick Lane. Posits an earlier much longer snowball period, c2.4 - c2.0 Gya, triggered by the Great Oxygenation Event.
- The information on eukaryotic lineage diversification was gathered from a New York Times opinion blog by Olivia Judson. See the text here: [1].
- Paleoproterozoic (chronostratigraphy scale)
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