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From Wikipedia, the free encyclopedia

Paleoarchean
3600 – 3200 Ma
Chronology
Proposed redefinition(s)4031–3490 Ma
Gradstein et al., 2012
Proposed subdivisionsAcastan Period, 4031–3810 Ma

Gradstein et al., 2012
Isuan Period, 3810–3490 Ma

Gradstein et al., 2012
Etymology
Name formalityFormal
Alternate spelling(s)Palaeoarchaean
Synonym(s)Early Archean
Usage information
Celestial bodyEarth
Regional usageGlobal (ICS)
Time scale(s) usedICS Time Scale
Definition
Chronological unitEra
Stratigraphic unitErathem
Time span formalityFormal
Lower boundary definitionDefined Chronometrically
Lower boundary GSSPN/A
GSSP ratifiedN/A
Upper boundary definitionDefined Chronometrically
Upper boundary GSSPN/A
GSSP ratifiedN/A
A stromatolite formed by Paleoarchean miocrobial mats, preserved as a fossil, from Pilbara craton, Western Australia
A stromatolite formed by Paleoarchean miocrobial mats, preserved as a fossil, from Pilbara craton, Western Australia

The Paleoarchean (/ˌpliɑːrˈkən/), also spelled Palaeoarchaean (formerly known as early Archean), is a geologic era within the Archaean eon. It spans the period of time 3,600 to 3,200 million years ago—the era is defined chronometrically and is not referenced to a specific level of a rock section on Earth. The name derives from Greek "Palaios" ancient. The oldest ascertained life form of fossilized bacteria in microbial mats, 3,480 million years old, found in the Dresser Formation in Western Australia, is from this era.[2][3] The first supercontinent Vaalbara formed during this period.

During this era, a large asteroid, about 37 to 58 kilometres (23–36 mi) wide, collided with the Earth in the area of South Africa about 3.26 billion years ago, creating the features known as the Barberton greenstone belt.[4]

References

  1. ^ Caredona, Tanai (6 March 2018). "Early Archean origin of heterodimeric Photosystem I". Heliyon. 4 (3): e00548. doi:10.1016/j.heliyon.2018.e00548. PMC 5857716. PMID 29560463. Retrieved 25 February 2021.
  2. ^ Borenstein, Seth (13 November 2013). "Oldest fossil found: Meet your microbial mom". AP News. Retrieved 15 November 2013.
  3. ^ Noffke, Nora; Christian, Daniel; Wacey, David; Hazen, Robert M. (8 November 2013). "Microbially Induced Sedimentary Structures Recording an Ancient Ecosystem in the ca. 3.48 Billion-Year-Old Dresser Formation, Pilbara, Western Australia". Astrobiology. 13 (12): 1103–24. doi:10.1089/ast.2013.1030. PMC 3870916. PMID 24205812. Retrieved 15 November 2013.
  4. ^ “Scientists reconstruct ancient impact that dwarfs dinosaur-extinction blast”, American Geophysical Union, April 9, 2014

External links


This page was last edited on 25 February 2021, at 20:30
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