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The Archean Eon (IPA: / ɑːr ˈ k iː ə n / ar-KEE-ən, also spelled Archaean or Archæan), in older sources sometimes called the Archaeozoic, is the second of the four geologic eons of Earth's history, preceded by the Hadean Eon and followed by the Proterozoic.
15 paź 2024 · The Archean Eon was preceded by the Hadean Eon, an informal division of geologic time spanning from about 4.6 billion to 4 billion years ago and characterized by Earth’s initial formation. Records of Earth’s primitive atmosphere and oceans emerge in the earliest Archean (Eoarchean Era).
Archean Eon, or Archaean Eon or Archeozoic Eon, Older of the two divisions of Precambrian time. The Archean begins with the formation of the Earth’s crust 4 billion years ago and extends to 2.5 billion years ago, up to the start of the Proterozoic Eon, the second division of the Precambrian Period.
28 lut 2020 · Unlike the Hadean, the Archean eon is divided into eras: the Eoarchean, Paleoarchean, Mesoarchean, and Neoarchean. The Neoarchean, which began about 2.8 billion years ago, was the era in which oxygenic photosynthesis began.
The Archean eon, which preceded the Proterozoic eon, spanned about 1.5 billion years and is subdivided into four eras: the Neoarchean (2.8 to 2.5 billion years ago), Mesoarchean (3.2 to 2.8 billion years ago), Paleoarchean (3.6 to 3.2 billion years ago), and Eoarchean (4 to 3.6 billion years ago).*
Each eon, era, period, and epoch is defined by major geological or paleontological events. The eons are the Hadean, Archean, Proterozoic, and Phanerozoic. The Phanerozoic Eon is the eon of visible life, and is divided into three eras: the Paleozoic, Mesozoic, and Cenozoic.
11 kwi 2024 · Life most likely started during the late Hadean or early Archean Eons. The earliest evidence of life are chemical signatures, microscopic filaments, and microbial mats. Carbon found in 4.1 billion year old zircon grains have a chemical signature suggesting an organic origin.
